Air supply system for film stretching unit

Abstract

The invention relates to an air supply system for a film stretching unit. The invention relates to an air supply system 2 for a stretching unit 1. The air supply system 2 comprises at least one air supply unit 100, at least one fresh air supply unit 102 and at least one exhaust gas return unit 106. The exhaust gas return unit 106 and the fresh air supply unit 102 are assigned to a common first treatment area 26c, wherein the fresh air supply unit 102 is configured to supply fresh air 300 as supply air 310 to the first treatment area. The exhaust gas return unit 106 is configured to draw the exhaust gas 200 from the first treatment zone 26c and to supply at least a portion 210, 212 of the exhaust gas 200 to the at least one air supply unit 100. The air supply unit (100) is assigned to a second processing area upstream of the first processing area (26c). The air supply unit (100) is configured to supply the portion (210, 211) of the exhaust gas returned by the exhaust gas return unit (106) as supply air (310) to the second processing area (26a, 26b).

Description

Technical Field

[0001] The present invention relates to an air supply system for a film stretching unit and a film stretching unit including an air supply system. Background Technology

[0002] Stretching units are specifically used for producing plastic films. So-called simultaneous stretching units are known, in which the plastic film can be stretched simultaneously in both the transverse and machine directions. Similarly, so-called sequential stretching units are known, in which the plastic film is stretched in two consecutive stages, for example, first in the machine direction and then in the transverse direction (or vice versa). Finally, stretching units that stretch only in the machine direction and only in the transverse direction are known.

[0003] In a typical stretching unit, a thin web of material to be stretched (e.g., a plastic film) is held at opposite edges by so-called grippers. The grippers are movably arranged on surrounding guide rails, through which the thin web of material is guided.

[0004] The grippers, and thus the material sheet they clamp, move sequentially from the entry area (where the edges of the material sheet to be stretched are held) to the exit area via an optional preheating area (where the material sheet is temperature-controlled) and a stretching area (where the grippers, positioned opposite each other, move divergently away from each other relative to the conveying direction on a guide rail section with lateral direction components). The grippers can then detach from the material sheet and move back to the entry area.

[0005] The stretching zone may be downstream of at least one so-called processing zone. Typically, the stretching zone is adjacent to at least one so-called annealing zone, in which the stretched material layer may undergo heat treatment. Heat treatment is specifically used to reduce the tension formed in the material layer due to stretching. One or more cooling zones may be adjacent to the at least one annealing zone. Other processing zones are also possible.

[0006] The plastic film must be temperature-controlled (heated or cooled) in a targeted manner before, during, and / or after the actual stretching process. For this purpose, the individual zones (i.e., the stretching zone and the potential processing zone) are temperature-controlled.

[0007] Furthermore, these areas are typically coupled to an air supply system that allows supply air to be delivered into the interior of the respective area and to extract contaminated or polluted air (exhaust). This is necessary because contaminants, such as monomers, oligomers, additives, auxiliaries (e.g., plasticizers), and / or the like, escape from the never fully cooled plastic film and accumulate or settle in the respective areas, thus causing contamination of the unit components and / or damage to the film quality.

[0008] However, ventilation of an area is very energy-intensive because the supplied air, especially when drawn from the environment, must be preheated according to regulations. Thin-film stretching units, including ventilation systems, are characterized by low energy requirements, as known for example from EP3650199B1. However, such ventilation systems are very complex, and the control of individual airflows requires a high level of effort. Summary of the Invention

[0009] Therefore, the object of the present invention is to provide an air supply system for a stretching unit and a stretching unit including the air supply system, which at least partially overcomes the above-mentioned disadvantages.

[0010] According to the invention, this objective is achieved by the air supply system and the stretching unit according to the independent claim. Other aspects of the invention are described in detail in the dependent claims and the following description.

[0011] Specifically, this objective is achieved by an air supply system for the stretching unit (specifically, the film stretching unit). The air supply system includes at least one air supply unit, at least one fresh air supply unit, and at least one exhaust return unit.

[0012] The exhaust return unit and the fresh air supply unit are assigned to a common first processing area.

[0013] A fresh air supply unit is configured to supply fresh air as supply air to the first processing area. The term "fresh air" here refers to the airflow that is first supplied to the processing area as supply air. In the simplest case, fresh air is drawn from the environment. Similarly, processing gases can be provided as fresh air, and / or these processing gases can be mixed with ambient air.

[0014] The exhaust return unit is configured to extract exhaust gas from the first processing area. Therefore, through the exhaust return unit and the fresh air supply unit, fresh air can be supplied to the first processing area, and at the same time, exhaust gas can be extracted.

[0015] Furthermore, the exhaust return unit is configured to supply at least a portion of the exhaust gas to an air supply unit. Another portion of the exhaust gas may be supplied to another air supply unit and / or extracted (to the environment). The exhaust gas can be filtered before it can dissipate into the environment, making it substantially free of contaminants.

[0016] An air supply unit is assigned to a second processing zone. This second processing zone is upstream of the first processing zone.

[0017] It can be directly adjacent to the first processing area, or an additional area, such as a neutral area or another processing area, can be arranged between the first and second processing areas. The air supply unit is configured to supply a portion of the exhaust gas returned to the air supply unit by the exhaust return unit as supply air to the second processing area.

[0018] In the case of a stretching unit, supply air can be provided above and / or below a thin layer of material (e.g., a plastic film). The supply air can be provided via nozzles and / or nozzle boxes. The nozzle box essentially distributes the airflow of the supply air across the width of the thin layer of material, such that the supply air flows as uniformly as possible over the thin layer of material.

[0019] If multiple air supply units (at least two) are provided, these air supply units can be supplied with a portion of the exhaust gas from the first processing area via an exhaust return unit. Furthermore, in this case, each air supply unit is assigned to a processing area upstream of the first processing area to supply supply air to that processing area.

[0020] The processing area may include at least one cooling area and / or at least one annealing area. Specifically, the processing area referred to herein as the first processing area may be a cooling area, in one aspect of the invention, after which no other processing area follows. The processing area referred to herein as the first processing area may, for example, be the final processing area of ​​a stretching unit. The second processing area may also be a cooling area.

[0021] The terms "first" and "second" processing zones do not indicate the order in which the processing zones are passed (e.g., by a thin layer of material). They are only used to distinguish between processing zones. In fact, the second processing zone is passed before the first processing zone. Therefore, the second processing zone is upstream of the first processing zone.

[0022] When fresh air is supplied to the first processing zone and subsequently exhausted, the fresh air supplied to the first processing zone comes into contact with the first processing zone and the materials contained therein (e.g., material thin layers, such as plastic films) only once. Therefore, the air does not circulate within the first processing zone. As a result, the exhaust gas removed from the first processing zone is relatively clean (and therefore contains little or no contaminants), and can thus be well reused in other upstream processing zones, stretching zones, and / or preheating zones without negatively impacting the quality of the materials being processed (e.g., material thin layers, such as plastic films). Furthermore, the fresh air in the first processing zone is preheated, which saves energy when temperature control is applied to the supply air for the corresponding upstream zones.

[0023] In one aspect, the air supply system is also configured to extract exhaust gas from the second processing area. The exhaust gas removed from the second processing area can be extracted at least partially. It can be filtered before it can dissipate into the environment, making it substantially free of contaminants.

[0024] The air supply unit may be further configured to mix at least a portion (0% to 100%) of the exhaust gas removed from the second processing zone with at least a portion of the exhaust gas supplied to the air supply unit from the exhaust gas return unit to generate a mixed airflow. The ratio of exhaust gas from the first processing zone to exhaust gas from the second processing zone may be substantially 5:1, substantially 4:1, substantially 3:1, substantially 2:1, substantially 1:1, substantially 1:2, substantially 1:3, substantially 1:4, or substantially 1:5.

[0025] In one aspect, the mixed airflow may include, for example, 1 / 3 of the exhaust from the first processing zone and 2 / 3 of the exhaust from the second processing zone.

[0026] Specifically, the mixed airflow can be mixed in such a way that the portion (or proportion) of contaminants is below a desired predetermined limit. Furthermore, the mixed airflow can be mixed in such a way that it has a desired temperature or is within a desired temperature range. For this purpose, appropriate sensors can be installed. By mixing the airflow, in particular, the lifespan of the filters in the air supply system (specifically, the air supply unit) can be improved and / or the level of contaminants in each processing area can be reduced.

[0027] Finally, the air supply unit can be configured to provide a mixed airflow as supply air to the second processing zone. The addition of exhaust gas from the second processing zone allows the supply air to be heated, thereby further saving energy.

[0028] Furthermore, the air supply system can be configured to supply fresh air separately to the first treatment area. Therefore, the level of contaminants can be kept very low in the exhaust gas from the first treatment area.

[0029] For example, the airflow supplied to the first, second, and / or any other zones can be controlled so that the concentration of pollutants in the exhaust is below a predetermined limit.

[0030] Furthermore, the residence time of air in the corresponding area can be determined by the supply airflow and / or exhaust airflow. The shorter the residence time, the lower the concentration of pollutants in the exhaust. Additionally, the desired pressure (overpressure, underpressure, atmospheric pressure) can be set in the corresponding area by the supply airflow and / or exhaust airflow. In particular, the lifespan of the filters in the air supply system (especially the air supply unit) can be improved and / or the level of pollutants in each treatment area can be reduced by adjusting the supply airflow and / or exhaust airflow.

[0031] Furthermore, the air supply unit can be configured to supply only a portion of the exhaust air supplied to it by the exhaust return unit, or a mixed airflow that does not contain fresh air, as supply air to the second processing area. Therefore, the supply air provided by the air supply unit to the processing area assigned to it does not contain fresh air. This enables energy-efficient operation because there is no need to heat (cold) fresh air. Simultaneously, the control workload is lower compared to previously known systems.

[0032] Furthermore, the exhaust return unit can be configured to extract all exhaust from the first processing area. Therefore, there is no additional exhaust outlet, and all heated fresh air can be supplied to other areas as supply air via the exhaust return unit.

[0033] Specifically, the air supply system includes at least one controllable fan, wherein the at least one controllable fan can be configured to

[0034] - Control the air supply flow to the first processing area, or

[0035] - Control the supply airflow to the second processing zone (or another processing zone or stretching zone), or

[0036] - Control the exhaust airflow in the first processing zone, or

[0037] - Control the exhaust airflow of the second processing area (or another processing area or stretching area), or - Control the airflow supplied by the exhaust return unit to the at least one air supply unit.

[0038] If multiple different airflows need to be controlled, such as to set a required pressure or to maintain a low concentration of contaminants in the processing area, multiple fans can be installed accordingly. The fans can be part of an air supply unit, a fresh air supply unit, and / or an exhaust return unit. Furthermore, at least one fan can be arranged in the air duct (supplying or exhausting air) of the air supply system or at another location within the air supply system.

[0039] Furthermore, the air supply system may include at least one heating element (e.g., an electric heating element, a fluid conduction heating element, a heat exchanger, and / or the like). The at least one heating element may, for example,

[0040] - Temperature control of the supply airflow to the first processing zone, or - Temperature control of the supply airflow to the second processing zone (or other processing or stretching zones).

[0041] Therefore, the temperature of the supplied air can be set or controlled. This improves production quality.

[0042] In addition, the air supply unit may include a condensate trap device having at least one condensation element.

[0043] Condensate traps are used to separate (or condense) contaminants entrained in exhaust gas.

[0044] For this purpose, the condensate trap device is configured to allow a portion of the exhaust gas to flow through it, said portion of the exhaust gas being supplied to the air supply unit by an exhaust gas return unit. This portion of the exhaust gas has a first temperature T1. Furthermore, this portion of the exhaust gas is used for temperature control of the condensation element.

[0045] Furthermore, the condensate trap device is configured to allow a portion (0% to 100%) of the exhaust gas drawn from the second processing zone to flow through it, said portion of the exhaust gas having a second temperature T2. The second temperature T2 is greater than the first temperature T1.

[0046] Due to the temperature difference, the temperature of the condensing element can be controlled so that contaminants entrained in the exhaust gas drawn from the second processing area are at least partially deposited (condensed) on the at least one condensing element.

[0047] In the production of plastic films, contaminants include monomers, oligomers, and / or other volatile substances that escape from the (still hot) plastic. These contaminants settle as a so-called "white powder" in the stretching unit and / or air supply system and can damage the film. For example, openings may become clogged, or moving parts (such as air control dampers) may become stiff or even blocked. Furthermore, their removal is laborious, as it typically requires stopping the stretching unit and interrupting production for removal. Condensate trapping devices now make it possible to remove contaminants from the airflow in a targeted manner before they settle. Therefore, unit lifespan can be increased and / or cleaning intervals can be extended. Additionally, the lifespan of potential filters can be significantly increased with condensate trapping devices.

[0048] Furthermore, the condensate trap device can be configured to mix the portion of the exhaust flowing through it to generate a mixed airflow. It has been shown that a very uniform mixed airflow can be obtained in this way. This leads to further improvements in production quality, particularly in (film) stretching units.

[0049] The air supply unit may also include a coarse filter device. This coarse filter device can filter out contaminants from the airflow that have passed through the condensate trap device. Therefore, the coarse filter device can be located downstream of the condensate trap device.

[0050] Route filter devices may include one or more route filters, such as metal braids, stretched plates, extended metal meshes, wire meshes, perforated plates, honeycomb panels, nonwoven filters, and / or the like. Route filters may be reusable (and therefore washable) or designed for single use.

[0051] A heating element can also be placed between the condensate trap device and the route filter device. Alternatively, a heating element can be placed after the route filter device.

[0052] Furthermore, the air supply unit may include a filter device comprising at least one filter that is typically finer than a coarse filter. Therefore, more contaminants can be removed from the airflow before it is supplied as supply air to the treatment area. The filter device is located, for example, downstream of the coarse filter device.

[0053] Furthermore, this objective is achieved by a stretching unit, particularly a film stretching unit, configured to stretch thin layers of material (e.g., plastic films) in the machine direction and / or transverse direction. The stretching unit includes a stretching region and at least two processing regions. These regions can be, for example, cooling regions and / or annealing regions as described above. Other processing regions are also possible.

[0054] Specifically, the processing area referred to herein as the first processing area can be a cooling area, and in one aspect of the invention, there are no other processing areas following this cooling area. The second processing area can also be a cooling area.

[0055] In addition, as mentioned above, the stretching unit includes an air supply system.

[0056] In another aspect of the invention, the preheating zone, stretching zone, and / or at least one annealing zone of the stretching unit may be supplied with only fresh air as supply air. The fresh air can be heated to the desired temperature by a heating element (e.g., a heat exchanger). Exhaust gas from the preheating zone, stretching zone, and / or said at least one annealing zone can dissipate into the environment and may optionally be filtered. This reduces the controllability of the individual airflows and the concentration of contaminants in the stretching unit. Attached Figure Description

[0057] The invention will now be explained in more detail by way of example with reference to the accompanying drawings. Here,

[0058] Figure 1 A schematic diagram of a stretching unit including an air supply system is shown.

[0059] Figure 2 A schematic diagram of the air supply system is shown;

[0060] Figure 3 A schematic diagram of the air supply unit is shown;

[0061] Figure 4 A schematic diagram of a condensate trap device is shown, and

[0062] Figure 5 A schematic diagram of a route filter device is shown. Detailed Implementation

[0063] Figure 1 A schematic diagram of the stretching unit 1, including the air supply system 2, is shown. Figure 2 The text then details several aspects of the air supply system 2.

[0064] The stretching unit shown is, for example, a film stretching unit 1 used to stretch a plastic film 10 (e.g., PET (polyethylene terephthalate)) in the machine direction and / or transverse direction. Similarly, stretching units can be used to stretch and / or process thin layers of other materials, such as PP (polypropylene), PE (polyethylene), PA (polyamide), or other plastics. The stretching unit is used to produce biaxially or uniaxially oriented films from (extruded) thin layers of material.

[0065] In the production of plastic film, molten film is first extruded through a die (e.g., a slit die) onto the cooling rollers of a film stretching machine. The cooled and at least pre-hardened melt (material sheet) is then removed from the film stretching machine and fed to the actual stretching unit 1. There, stretching is performed in at least one stretching zone 20 along the machine direction and / or transverse direction, and possible post-treatments, such as annealing or cooling, are carried out on the stretched material sheet (plastic film) 10 in corresponding processing zones (annealing zones 24a-d and cooling zones 26a-26c).

[0066] The plastic film passes through the stretching unit 1 in the so-called stretching direction A. After passing through the stretching unit 1, the stretched plastic film can, for example, be wound up.

[0067] The regions, which can be referred to as neutral regions 22a, 22b, and 22c, are separated, and no specific processing occurs in these regions. Specifically, neutral regions 22a and 22b can be arranged between different types of regions, such as between stretching region 20 and annealing regions 24a-d, and between annealing regions 24a-d and cooling regions 26a and 26b. Here, another neutral region is located between cooling region 26b and cooling region 26c, which is the last region of the stretching unit. Therefore, there are no further processing regions after cooling region 26c.

[0068] In annealing zones 24a-d, the plastic film 10 can be heat-treated, particularly after the stretching process in stretching zone 20 has ended. As a result, for example, relaxation of the plastic film 10 can be achieved. Figure 1 As shown, the multiple annealing zones 24a-d can be part of a stretching unit. For example, the stretching unit may include at least five, at least seven, or at least nine annealing zones. The annealing zones may be controlled at different temperatures to achieve the desired heat treatment.

[0069] In cooling zones 26a, 26b, and 26c, the plastic film is then cooled to a degree that allows it to be further processed and / or packaged for further processing (e.g., winding). If multiple cooling zones 26a, 26b, and 26c are provided, the temperature in the cooling zones can be reduced along the pulling direction A. This enables the gradual and slow cooling of the plastic film 10.

[0070] The stretching unit 1, which includes at least one annealing region 24a-d, at least one neutral region 22a-c, and / or at least one cooling region 26a-c, may include one or more air circulation devices (e.g., in the form of a fan) and / or heating devices. These may be arranged above and / or below the plastic film 10 or the thin layer of material (indicated by a fan symbol).

[0071] The stretching unit 1 is, in principle, a simultaneous stretching unit, in which the plastic film 10 is stretched simultaneously in the actual stretching area 20, and thus simultaneously in both the machine direction and the transverse direction. Similarly, the stretching unit 1 can be a sequential stretching unit, in which the plastic film 10 is stretched, for example, first in the machine direction and then in the transverse direction (or vice versa). However, the stretching unit 1 can also, in principle, simply be a transverse orientation device, in which the plastic film 10 is stretched transversely to the direction of film travel.

[0072] An air supply system 2 is provided for ventilation and air extraction in various areas.

[0073] In the embodiment shown here, a fresh air supply unit 104 is allocated to the stretching zone 20. The stretching zone 20 typically includes a preheating zone through which the thin film of material to be stretched can be preheated to a desired temperature. The fresh air supply unit 104 includes a fan that draws in fresh air through a filter 130 and supplies it to the stretching zone 20 as supply air 310. The filtered fresh air can also be temperature-controlled to a desired temperature by a heating element 150. In the example shown here, the supply air 310 is supplied to different locations within the stretching zone 20 via a supply air distributor 312. For example, the supply air can be supplied to the stretching zone 20 via a nozzle box located below and / or above the plastic film 10.

[0074] Supply air flows through the plastic film in the stretching zone 20, absorbing contaminants (especially oligomers) in this process. The contaminated air can be exhausted from the stretching zone as exhaust gas via another fan 140. Specifically, the exhaust gas can be removed from the stretching zone at different locations and drawn in via the fan through the exhaust gas collector 202. This ventilation and extraction of air in the stretching zone 20 is characterized by its simple controllability. In one aspect, fault-prone dampers, especially multi-leaf dampers, can be omitted to control airflow.

[0075] Fresh air supply units 104 are also assigned to annealing zones 24a-24d, and are constructed in a similar manner to those assigned to stretching zones 20 (or preheating and stretching zones). Therefore, the fresh air supply units 104 for annealing zones 24a-24d include fans that draw in fresh air via filters 130 and supply it as supply air 310 to annealing zones 24a-24d. The filtered fresh air can also be temperature-controlled to a desired temperature by heating elements 150. In the example shown here, supply air 310 is supplied to different locations within annealing zones 24a-24d or to different annealing zones 24a-24d via supply air distributors 312. It should be understood that multiple fresh air supply units may also be provided for ventilation and air extraction from annealing zones 24a-24d.

[0076] Supply air flows over a plastic film in annealing zones 24a-24d, where it absorbs contaminants (particularly oligomers). The contaminated air can be exhausted from annealing zones 24a-24d as exhaust gas via another fan 140. Specifically, exhaust gas can be removed from annealing zones 24a-24d at different locations and drawn in via exhaust gas collector 202 through fan 140. This ventilation and extraction in annealing zones 24a-24d is characterized by its simple controllability.

[0077] Air ventilation and extraction in cooling zones 26a, 26b and 26c Figure 2 The details are shown in the diagram and described below. Optionally, neutral zones may also be ventilated, and air may be drawn from them. Similarly, controlled air exchange may not occur in neutral zones.

[0078] Figure 2 A schematic diagram of the air supply system 2 is shown, which supplies (ventilates) supply air to cooling zones 26a, 26b and 26c and removes (extracts) exhaust air.

[0079] The air supply system 2 includes at least one air supply system 100 (two in the illustrated exemplary embodiment). The air supply unit 100 is assigned to cooling zone 26a or cooling zone 26b and supplies supply air 310 to these cooling zones. The airflow of the supply air 310 can be controlled via a separate fan 140. Figure 3 The structure of the air supply unit 100 is shown in detail and described with reference to the figure.

[0080] Furthermore, the air supply system 2 includes a fresh air supply unit 102. This is allocated to the cooling zone 26c. The fresh air supply unit 102 supplies fresh air 300 as supply air 310 to the cooling zone 26c. The fresh air supply unit 102 includes a fan that draws in fresh air via a filter 130 and supplies it as supply air 310 to the cooling zone 26c. The filtered fresh air can also be temperature-controlled to a desired temperature by a heating element 150. In the example shown here, the supply air 310 is supplied to the cooling zone 26c via two additional controllable fans 140. The supply air to the cooling zone 26c preferably consists only of fresh air.

[0081] Supply air flows over the plastic film in cooling zone 26c, absorbing any potential residual contaminants, and is drawn in as exhaust 200 through exhaust return unit 106. Exhaust return unit 106 includes, for example, a fan by which the exhaust airflow can be controlled. In exhaust return unit 106, the exhaust flow can be divided into a portion 210 and a portion 211. This can be achieved by a corresponding controllable fan. Similarly, controllable valves and / or dampers 160 can be provided to control the airflow. Furthermore, a backflow damper can be provided to prevent unwanted backflow of supply air and / or exhaust.

[0082] Portions 210 and 211 of the exhaust gas removed from cooling zone 26c can be supplied to air supply unit 100. The remaining portion can also dissipate into the environment. The exhaust return unit 106 can be constructed such that the ratio of portions 210 and 211 can be set or controlled. For example, 40% of the exhaust gas removed from cooling zone 26c can be supplied as portion 210 to air supply unit 100 allocated to cooling zone 26a. Furthermore, 55% of the exhaust gas removed from cooling zone 26c can be supplied as portion 211 to air supply unit 100 allocated to cooling zone 26b. The remaining 5% can be dissipated into the environment. This ratio is generally not fixed but can be freely set.

[0083] In the air supply unit 100, the exhaust portions 210, 211 drawn from the cooling zone 26c are first guided into the condensate trap device 110 (see...). Figure 3 In addition, at least a portion 212 of the exhaust gas is supplied to the condensate trap device 110, and the exhaust gas is removed from the cooling zones 26a, 26b allocated by the air supply unit 100.

[0084] To extract exhaust 200 and separate exhaust in portion 212, at least one (controllable) fan 140 and / or at least one controllable valve or at least one damper may be provided.

[0085] In the condensate trap device 110, contaminants, particularly those from the exhaust section 212, can be separated and condensed. Furthermore, a mixed airflow 214 is generated, comprising sections 210 as well as sections 211 and 212. The function of the condensate trap device 110 will combine... Figure 4 To provide a more detailed explanation.

[0086] The air supply unit 100 may be specifically designed such that no fresh air is supplied to the assigned processing area (here, cooling areas 26a and 26b), but only exhaust air that has been removed from the subsequent or final processing or cooling area 26c, as well as return exhaust air from the assigned processing area.

[0087] After passing through the condensate trap device 110, the mixed airflow can be guided through the route filter device 120 and the filter device 130. The condensate trap device prevents the filters from clogging rapidly and requires frequent replacement. Additionally, a heating element 150 can be provided to control the temperature of the mixed airflow 214. As shown, the heating element 150 can be arranged between the route filter device 120 and the filter device 130. Similarly, the heating element 150 can be arranged upstream of the route filter device 120 or downstream of the filter device 130.

[0088] A mixed and, if applicable, temperature-controlled airflow 214 can be supplied to the assigned processing area, for example, via a fan 140 as supply air.

[0089] exist Figure 4 The diagram illustrates the function of an exemplary condensate trap device 110. The condensate trap device 110 includes at least one condensation element 112. The condensation element 112 is a component comprising a large surface area on which contaminants (particularly oligomers) settle or condense. Through the settling of contaminants, relative contaminants in the air are treated to settle. The condensate trap device is preferably designed in a manner that facilitates cleaning. Therefore, the air conveyed forward is considerably cleaner.

[0090] Specifically, portions 210 and 211 of the exhaust gas supplied from the exhaust return unit 106 to the air supply unit 100 are guided through the condensate trap device 110 in such a way that the condensing element 112 is temperature-controlled below the condensation temperature of the contaminants. The portions 210 and 211 of the exhaust gas supplied from the exhaust return unit 106 to the air supply unit 100 may here have a first temperature T1 or be correspondingly temperature-controlled. In the example shown, portion 210 is guided through a conduit coupled to the condensing element 112 in a manner capable of transferring heat.

[0091] The portion 212 of exhaust gas extracted from the assigned processing areas (here, cooling areas 26a and 26b) is directed to the temperature-controlled condenser element 112. In doing so, contaminants are condensed.

[0092] The embodiment of the condensate trap device 110 shown here is merely exemplary, and other condensate trap devices 110 may also be used.

[0093] To clean the condensate trap device 110 and remove condensate, the condensate element 112 or multiple condensate elements 112 may be removed and replaced, or may be cleaned.

[0094] Figure 5 A schematic diagram of a route filter assembly 120 is shown. A mixed airflow 214 flows through the coarse filter assembly 120. The route filter assembly 120 includes multiple route filters 124 (e.g., woven metal, stretched plates, extended metal mesh, wire mesh, perforated plates, honeycomb panels, nonwoven filters, and / or the like) inserted into corresponding filter frames 122. The route filters 124 may be reusable or replaceable after use.

[0095] List of reference numerals

[0096] 1 Thin Film Stretching Unit

[0097] 2. Air supply system

[0098] 10. Thin layers of materials (e.g., plastic films)

[0099] 20. Stretching zone (specifically, with a preheating zone).

[0100] 22a Neutral Region

[0101] 22b Neutral Region

[0102] 22c neutral region

[0103] 24a Annealing Zone

[0104] 24b annealing zone

[0105] 24C annealing region

[0106] 24d annealing zone

[0107] 26a Cooling Zone

[0108] 26b Cooling Zone

[0109] 26c cooling area

[0110] 100 air supply units

[0111] 102 Fresh Air Supply Unit

[0112] 104 Fresh Air Supply Unit

[0113] 106 Exhaust Return Unit

[0114] 110 Condensate Trap Device

[0115] 112 Breathable Element (Porous Plate)

[0116] 114 Air Duct

[0117] 120 Route Filter Device

[0118] 122 filter frame

[0119] 124 route filter

[0120] 130 filter unit

[0121] 140 fan

[0122] 150 heating element

[0123] 160° air damper (return air damper)

[0124] 200 exhaust

[0125] 202 Exhaust Collector

[0126] 210 returned exhaust (T1)

[0127] 212 Returned exhaust (T2 > T1)

[0128] 214 Mixed Airflow

[0129] 300 Fresh Air

[0130] 310 air supply

[0131] 312 air distributor

[0132] A Pull-out direction

Claims

1. An air supply system (2) for a stretching unit (1), the stretching unit (1) being particularly a film stretching unit; the air supply system (2) comprising: At least one air supply unit (100); At least one fresh air supply unit (102), and At least one exhaust return unit (106), wherein The exhaust return unit (106) and the fresh air supply unit (102) are assigned to a common first processing area (26c), in which The fresh air supply unit (102) is configured to supply fresh air (300) as supply air (310) to the first processing area (26c), and wherein The exhaust return unit (106) is configured to draw exhaust gas (200) from the first processing area (26c) and supply at least a portion (210, 211) of the exhaust gas (200) to at least one air supply unit (100), wherein An air supply unit (100) is assigned to a second processing area (26a, 26b) upstream of a first processing area (26c), and wherein the air supply unit (100) is configured to The portion (210, 211) of the exhaust gas supplied to it by the exhaust return unit (106) is provided as supply air (310) to the second processing area (26a, 26b).

2. The air supply system (2) according to claim 1, wherein the air supply system is further configured to draw exhaust gas (200) from the second processing area (26a, 26b), and wherein... The air supply unit (100) is also configured to mix at least a portion (212) of the exhaust gas (200) drawn from the second processing area (26b) with at least a portion (210, 211) of the exhaust gas supplied to the air supply unit (100) by the exhaust gas return unit (106) to generate a mixed air flow (214), and to supply the mixed air flow (214) as supply air (310) to the second processing area (26a, 26b).

3. The air supply system (2) according to claim 1 or 2, wherein, The air supply system (2) is configured to supply only fresh air (300) as supply air (310) to the first processing area (26c).

4. The air supply system (2) according to any one of claims 1 to 3, wherein, The air supply unit (100) is configured to... The portion (210, 211) of the exhaust supplied to it solely by the exhaust return unit (106) or a mixed airflow (214) excluding fresh air. As supply air (310), it is supplied to the second processing area (26a, 26b).

5. The air supply system (2) according to any one of claims 1 to 4, wherein, The exhaust return unit (106) is configured to extract all exhaust gas (200) from the first processing area (26c).

6. The air supply system (2) according to any one of claims 1 to 5, wherein, The air supply system (2) includes at least one controllable fan (140), wherein the at least one controllable fan (140) is configured to - Control the supply airflow to the first processing area (26c), or - Control the supply airflow to the second processing zones (26a, 26b), or - Control the exhaust airflow in the first processing zone (26c), or - Control the exhaust airflow in the second processing zones (26a, 26b), or - Control the airflow supplied by the exhaust return unit (106) to the at least one air supply unit (100).

7. The air supply system (2) according to any one of claims 1 to 6, wherein, The air supply system (2) includes at least one heating element (150), wherein the at least one heating element (150) is configured to - Temperature control is applied to the supply airflow to the first processing zone (26c), or - Temperature control is performed on the supply airflow to the second processing zones (26a, 26b).

8. The air supply system (2) according to any one of claims 1 to 7, wherein, The air supply system (100) includes a condensate trapping device (110) having at least one condensing element (112), wherein the condensate trapping device (110) is configured to A portion of the exhaust gas (210, 211) flows through it, said portion (210, 211) of the exhaust gas is supplied to the air supply unit (100) by the exhaust gas return unit (106) and has a first temperature (T1) for temperature control of the condensing element (112); wherein, the condensate trap device (110) is also configured to A portion (212) of the exhaust gas (200) drawn from the second processing zone (26b) is allowed to flow through it, the portion (212) having a second temperature (T2) greater than a first temperature (T1), and wherein the at least one temperature-controlled condensing element (112) is configured such that... The contaminants entrained in the exhaust gas (200) drawn from the second processing zone (26b) are at least partially condensed on the at least one condensing element (112).

9. The air supply system (2) according to claim 8, wherein, The condensate trap device (110) is also configured to mix the airflow through its exhaust section (210, 211, 212) to generate a mixed airflow.

10. The air supply system (2) according to any one of claims 8 or 9, wherein, The condenser element (112) includes a perforated plate or a honeycomb structure.

11. The air supply system (2) according to any one of claims 1 to 10, wherein, The air supply unit (100) also includes a route filter device (120), which is optionally located downstream of the condensate trap device (110).

12. The air supply system (2) according to any one of claims 1 to 11, wherein the air supply unit (100) further includes a filter device (130), the filter device (130) optionally being located downstream of the route filter device (120).

13. The air supply system (2) according to any one of claims 1 to 12, wherein, The air supply system (2) includes multiple air supply units (100), wherein an exhaust return unit (106) is configured to draw exhaust gas (200) from the first processing area (26c) and supply at least a portion (210, 212) of the exhaust gas (200) to the air supply unit (100), wherein Air supply units (100) are respectively assigned to processing areas upstream of the first processing area to supply supply air (310) to the processing areas.

14. A stretching unit (1), particularly for stretching a plastic film (10) in the machine direction and / or transverse direction, wherein the stretching unit (1) comprises Stretched area (20); At least two processing zones (24a-d, 26a-c) are arranged downstream of the stretching zone (20), and The air supply system (2) according to any one of claims 1 to 13.

15. The stretching unit (1) according to claim 14, wherein the at least two processing regions (24a-d, 26a-c) include at least one cooling region (26a-c) and / or at least one annealing region (24a-d), and wherein the first processing region (26c) is optionally a processing region without any subsequent processing regions.

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