Apparatus and a method for producing a film web

Abstract

The invention describes a device (200) for producing a plastic film web (2) with an extrusion unit (202). The extrusion unit has a die head (204) for ejecting a plastic melt (206) from an outlet and a take-off unit (214) for drawing off the plastic melt (206) and the resulting film web (2) in a take-off direction (Z). Furthermore, the device has a longitudinal stretching unit (1) for monoaxially stretching the film web (2) in a machine direction (M) with a roller arrangement comprising at least two functional rollers. The film web (2) can be conveyed in the machine direction (M) via the roller arrangement. At least two functional rollers are designed as stretching rollers (6) and can be driven at different circumferential speeds to stretch the film web (2).The longitudinal stretching device (1) comprises at least one cleaning device which is designed to be attached to and detached from at least one of the functional rollers for cleaning that roller. It further comprises at least one cutting device which, viewed in the machine direction (M), is positioned in front of the cleaning device and is retractable into and out of the film web (2) perpendicular to a transverse extension of the film web (2), so that the film web (2) can be cut longitudinally in such a way that a cleaning gap, accessible to the cleaning device, can be formed in the film web (2). The invention further relates to the longitudinal stretching device (1) and a cleaning method for a functional roller.

Description

[0001] The invention relates to a device and a method for producing a film web, e.g., a blown film line. The device comprises an extrusion unit with a die head for ejecting a polymer melt from an outlet. Furthermore, the device includes a take-up unit for drawing off the polymer melt and the resulting film web in one machine direction. A longitudinal stretching unit is also provided, by means of which the film web can be stretched monoaxially in one machine direction. The longitudinal stretching unit comprises a roller assembly for transporting the film web. The roller assembly has at least two functional rollers, at least two of which are designed as stretching rollers and can be driven at different circumferential speeds to stretch the film web.Furthermore, the longitudinal stretching device includes at least one cleaning device which is designed to be attachable to and detachable from at least one of the functional rollers for cleaning that functional roller.

[0002] The invention further relates to a longitudinal stretching device with a cleaning device and a method for cleaning a functional roller of a longitudinal stretching device.

[0003] A longitudinal stretching device for a device for producing a film web is known, for example, from DE 20 2022 002 614 U1.

[0004] Such a longitudinal stretching unit can be designed or arranged directly as a station within a film extrusion line, be it a blown film line or a cast film line. However, it can also be provided that the longitudinal stretching unit for post-treatment of the respective extruded film is operated as an independent unit "offline" from the film extrusion line.

[0005] The longitudinal stretching unit, also called an MDO (machine direction orientation) stretching unit, typically consists of a roller assembly with a multitude of functional rollers, for example, temperature-controlled chrome rollers, which rotate or are driven at different speeds. The individual functional rollers are arranged very close together to minimize the free film length of the film web to be stretched between the respective rollers. By means of functional rollers designed as guide rollers, which also act as pressure rollers, or by other means, the film web is held on the functional rollers designed as stretching rollers, which are preferably made of chrome, and stretched in the machine direction or longitudinally, whereby the crystals in the film web align in the direction of tension or in the machine direction, and the film web acquires different properties.The MDO treatment itself is known from the prior art, so the process itself and the function of the respective functional rollers will not be discussed in detail.

[0006] The appearance of a film, particularly its transparency, is influenced by many parameters during MDO treatment. Contamination of the functional rollers involved in the MDO process, especially the guide roller(s), heating roller(s), stretching roller(s), cooling roller(s), and annealing roller(s), also known as tempering roller(s), has a significant negative impact. Therefore, it is known from the prior art to interrupt or stop the MDO process to clean the respective functional roller(s) and to unthread or detach the film web from the respective functional roller(s) so that the respective functional roller(s) can be cleaned in the longitudinal stretching unit, particularly by means of a cleaning device.It is also known to reduce the MDO treatment so that the respective functional roller(s) are accessible for disassembly and subsequent cleaning outside the longitudinal stretching unit. Disassembly of the functional rollers for cleaning, in particular, requires the rollers to first be cooled down and then reheated after reassembly, which is both costly and energy-intensive. For example, a stretching roller for cleaning must be cooled from 115°C to approximately 40°C and then reheated. In total, three hours or more regularly elapse between production stoppage and restart. Depending on the respective operating times and the specific production and longitudinal stretching parameters, cleaning is required regularly every one to two days to ensure a sufficiently consistent (high) film quality.

[0007] The object of the present invention is therefore to provide a device and a method which overcome the disadvantages known from the prior art, in particular to provide low-effort cleaning of at least one of the functional rollers, preferably without having to unwind and rewind the film web from the respective functional rollers.

[0008] According to the invention, this problem is solved by all the features of claim 1. Possible embodiments of the invention are specified in the dependent claims.

[0009] According to the invention, at least one cutting device is provided, which, viewed in the machine direction, is formed in front of the cleaning device and can be inserted into and removed from the film web perpendicular to a transverse extension of the film web, so that the film web can be cut in the longitudinal direction in such a way that a cleaning gap is formed in the film web which can be penetrated by the cleaning device.

[0010] Since the cleaning device can reach through the cleaning gap in the film web, it is possible to attach the cleaning device to the functional roller to be cleaned during ongoing production, without having to unwind and rewind the film web from the respective functional rollers. In contrast to known cleaning devices, the embodiment according to the invention therefore does not require interrupting production and unwinding and re-threading the film web for cleaning. Disassembly and assembly, as is known in particular for manual cleaning of the respective functional rollers, are eliminated, as are the cooling and heating phases required for this process.

[0011] The device for producing the film web can, in particular, be a blown film line with a nozzle head designed as a blowing head, a calibration basket, and a flattening unit. The take-off unit is also preferably designed as a reversing take-off unit.

[0012] Another variant involves using a cast film production line. In this variant, the nozzle head is expediently designed as a wide-slot nozzle.

[0013] Both blown film production lines and cast film production lines are familiar to the expert, so further explanations are omitted here.

[0014] Advantageously, the roller arrangement of the longitudinal stretching device may include, in addition to the two functional rollers designed as stretching rollers, at least one additional functional roller designed as a guide roller for guiding and / or pressing the film web. Alternatively or additionally, the roller arrangement may also include at least one additional functional roller designed as a heating roller for heating the film web and / or at least one additional functional roller designed as a cooling roller for cooling the film web and / or at least one additional functional roller designed as an annealing roller for tempering the film web.

[0015] In practice, it has proven particularly advantageous in blown film lines if, according to a specific embodiment of the invention, the cutting device is arranged in front of or within the take-off unit when viewed in the machine direction. In particular, the cutting device in the take-off unit of a blown film line can be designed such that it punctures and / or cuts a bubble shape formed from the molten plastic in the film material. This has the advantageous effect of allowing air trapped in the bubble shape, which remains between the layers of the flattened film bubble, especially during the start-up process, to escape.

[0016] An alternative, equally advantageous variant involves arranging the cutting device in the machine direction in an area between the take-off unit and the longitudinal stretching unit. A cutting device positioned along the film web between the take-off unit and the longitudinal stretching unit can also serve as a lead-in / threading aid to guide the film web into the longitudinal stretching unit, particularly during production start-up.

[0017] Another highly advantageous embodiment provides that the longitudinal stretching unit itself includes the cutting device. It is expediently possible for the cutting device to be arranged, in particular upstream of the first functional roller, as viewed in the machine direction. This variant is especially suitable due to its advantageous accessibility when the functional rollers are arranged very close together and / or for retrofitting the cutting device to an existing longitudinal stretching unit or for assembly / maintenance purposes. This variant is also advantageous if more than one functional roller of the roller arrangement of the longitudinal stretching system is designed to be cleanable by means of a cleaning device, in particular one cleaning device for each roller.

[0018] Alternatively, the cutting device can be arranged directly in front of the functional roller to be cleaned, such that it is positioned in an area between the functional roller to be cleaned and the functional roller located in front of it in the machine direction. This arrangement has the advantage that the cutting device is integrated into the longitudinal stretching unit, which allows for a particularly compact design and simultaneously improves occupational safety by reducing or eliminating accessibility within the longitudinal stretching unit. This design or arrangement is especially advantageous when the cutting device and the cleaning device are arranged directly next to each other in the machine direction on a common bearing unit and / or are designed as a single cutting and cleaning device.

[0019] A further advantageous embodiment of the invention is achieved by the cutting device having at least one blade element for slitting the film web. Advantageously, the cutting device additionally includes a slitting device, which, viewed in the machine direction, is arranged behind the at least one blade element and is designed such that the cut edges of the film web resulting from the slitting are widened in directions parallel to the transverse extent of the film web, diverging from each other.

[0020] A particularly simple design can also be achieved by arranging, for example, the splitting device and the cutting device and / or the cleaning device directly next to each other on a common bearing unit in the machine direction. Alternatively, the splitting device and the cutting device and / or the cleaning device can be designed as a single, combined splitting, cutting, and / or cleaning device.

[0021] According to a further preferred embodiment of the invention, the slitting device is arranged and designed as a folding device such that the cut edges of the film web, which are created when the film web is cut, are folded parallel to the transverse extent of the film web in mutually repelling folding directions. Advantageously, this results in the cleaning gap being limited by double-layered film web edge sections.

[0022] An advantage of this design variant is that the cleaning gap is limited by double-layered film web edge sections. These double-layered film web edge sections prevent tearing of the film web when the cleaning gap is created, especially compared to simply spreading the film web edge sections without folding them over, which would result in creases forming in the film web edge sections. Furthermore, the folding allows the film web edge sections to be transported in such a way that the individual film web layers of the double-layered film web edge sections lie flat on top of each other as they are transported over the respective functional rollers of the longitudinal stretching unit. This also prevents tearing and / or uncontrolled behavior of the film web during its passage through the longitudinal stretching unit.

[0023] Support for the double-layered film web edge sections can advantageously be achieved by the folding device having at least one pressure roller. The pressure roller is advantageously designed such that pressure is exerted on the fold line of the double-layered film web edge sections created during folding, so that the double-layered film web edge sections are fixed or can be fixed in place.

[0024] Another optional variant provides that the slitting device is designed as a (banana) spreading roller, which is designed in such a way that when the film web is guided over the (banana) spreading roller, the cut edges of the film web are widened in directions that repel each other, parallel to the transverse extension of the film web.

[0025] In practice, a variant has also proven advantageous, particularly in counteracting creasing within the film web that can occur when the cleaning gap is widened by means of a slitting device. This advantageous embodiment is characterized in that the cutting device has at least two parallel blade elements for cutting the film web. The blade elements are designed such that, as the cutting device is inserted into the film web, they cut out a strip of film along the machine direction. Advantageously, a discharge device, for example in the form of a suction device, is provided, which is arranged and designed behind the two blade elements when viewed in the machine direction. The discharge device preferably separates the film strip cut from the film web.In this variant, the cleaning gap is formed by a strip-shaped gap remaining in the film web, where the cut-out film strip previously ran in the film web.

[0026] According to an alternative or supplementary embodiment, the cleaning device may have a threading aid extending against the machine direction, preferably a threading aid designed as a gap device. The threading aid may be essentially wedge-shaped. The threading aid, particularly due to its conical shape extending against the machine direction, is designed such that the cleaning device can be threaded into the cleaning gap when positioned against the functional roller to be cleaned, and the film web can be guided around the cleaning device. The threading aid ensures safe insertion into the cleaning gap, safe passage through the cleaning gap, and safe positioning against the functional roller to be cleaned. The threading aid is particularly advantageous for very narrow cleaning gaps.

[0027] To provide the most comprehensive cleaning functionality possible, a special variant features a cutting device that moves parallel to a transverse axis of the film web and a cleaning device that moves parallel to a longitudinal axis of the functional roller being cleaned. Because the cleaning device can move parallel to the longitudinal axis of the functional roller, it is able to clean the roller over a larger axial range. Since the cutting device also moves parallel to a transverse axis of the film web, the cleaning gap provided by the cutting device can move with the position of the cleaning device, ensuring that the cleaning device always maintains full contact with the functional roller and can thus clean the roller completely.

[0028] In particular, a further embodiment is based on the fact that at least one cleaning device has at least one electric cleaning device motor, and that this motor allows the device to be connected to and disconnected from the functional roller to be cleaned, and to be moved parallel to the longitudinal axis of the functional roller. Since the longitudinal stretching device is often enclosed or covered due to space constraints and / or safety precautions, and / or is inaccessible to an operator, at least during ongoing production, the at least one electric cleaning device motor for moving the cleaning device has proven to be particularly advantageous. Furthermore, the electric cleaning device motor allows the required installation space of the longitudinal stretching device with its motor-driven cleaning device to be kept to a minimum.

[0029] In practice, it has proven particularly advantageous if the cutting device has at least one cutting device motor and can be moved into and out of the film web and / or parallel to the transverse extent of the film web by means of the at least one electric cutting device motor, so that even with this advantageous variant of the cutting device, the installation space for the cutting device, in particular the installation space within the longitudinal stretching device, can be kept small and process reliability can be increased.

[0030] It can also be provided that, in the advantageous embodiment in which the cleaning device and the cutting device are arranged directly adjacent to each other in the machine direction on the common bearing unit and / or are designed as a common cutting and cleaning device, the cutting device and the cleaning device are movable together by means of at least one common electric motor at least parallel to the transverse extent of the film web or parallel to the longitudinal axis of this functional roller to be cleaned, and preferably can be moved together into and out of the film web or positioned against and lifted away from the functional roller to be cleaned.

[0031] Preferably, at least one cleaning device motor is connected to, or connectable to, a control unit and can be controlled by this control unit. Preferably, at least one cutting device motor is also connected to the control unit and can be controlled by the control unit. The control unit can be designed as a remote control operated by an operator, which sends a control signal selected by the operator in real time to the respective cleaning device motor and / or to the respective cutting device motor.

[0032] It may be advantageous to design the control unit to be integrated into the longitudinal stretching device.

[0033] It is particularly within the scope of the invention that the movement of the cutting device parallel to the transverse extent of the film web and / or the extension and retraction of the cutting device into and out of the film web and / or the movement of the cleaning device axially to the functional roller to be cleaned and / or the connection and disconnection of the cleaning device to the functional roller to be cleaned are carried out manually and / or by means of an electric motor, in particular the at least one cleaning device motor or the at least one cutting device motor. The respective motors can be controlled by the control unit by manual input via remote control or by a control program running in the control unit.

[0034] The control unit also enables synchronization of the cleaning device and the cutting device, so that, for example, depending on a specific / determinable position of the cutting device relative to the transverse extent of the film web and / or the cleaning gap in the film web, the control unit can actuate at least one cleaning device motor in such a way that the cleaning device adapts to the changing course of the cleaning gap when the cutting device is displaced. It can also be provided that when the cutting device enters the film web, the cleaning device or at least one cleaning device motor is actuated in such a way that the cleaning device, penetrating the respective cleaning gap provided by the cutting device, positions itself against the functional roller to be cleaned.It can also be advantageously provided that, when the cutting device is extended from the film web, the cleaning device or at least one cleaning device motor is controlled in such a way that the cleaning device moves from a position positioned against the functional roller to be cleaned into the switched-off position and out of the cleaning gap.

[0035] It may be advantageous to provide that the displacement of the cutting device parallel to the transverse extension of the film web and / or the insertion or removal of the cutting device into the film web is carried out manually or by means of the at least one cutting device motor, which is controlled by the control unit by manual input via the remote control or by a control program running in the control unit.

[0036] For the automation of the cleaning process, a particular embodiment provides a sensor unit. A further variant provides that the longitudinal stretching device includes the sensor unit. This sensor unit is advantageously connected or connectable to the control unit and configured to detect the position of the cleaning gap in the film web in a section viewed in the machine direction upstream of the functional roller to be cleaned. It is advantageously provided that the control unit is configured to control the at least one cleaning device motor depending on the position of the cleaning gap in the film web. Advantageously, in this variant, the cleaning device is designed to follow the path of the cleaning gap, regardless of the type of movement of the cutting device or the method by which this movement of the cutting device is provided.to enter or exit the respective cleaning gap.

[0037] In practice, it has been shown that the service life of the respective longitudinal stretching device can be improved by ensuring that at least one of the stretching rollers, as the functional roller to be cleaned, can be cleaned by the cleaning device of the aforementioned type.

[0038] In particular, if the device is designed to clean two or more functional rollers, it may be provided that a separate cleaning device is provided for each functional roller to be cleaned.

[0039] Another variant for cleaning more than one functional roller provides that the cleaning device is movably mounted on a motor-driven, in particular electric, positioning frame in two or more cleaning positions relative to the functional rollers, so that the cleaning device is arranged to clean a different functional roller in each cleaning position. In particular, with such a positioning frame and one cleaning device, the functional rollers to be cleaned can only be cleaned one after the other. Further variants therefore provide that two or more cleaning devices are expediently mounted on the positioning frame, wherein preferably at least one, and in particular all, of the cleaning devices are movably mounted relative to the functional rollers in two or more cleaning positions each, such that the cleaning device or...The cleaning devices are arranged in each cleaning position to clean a different functional roller.

[0040] Further variations may provide that the device for producing the film web, in particular the longitudinal stretching unit, has two opposing positioning stands, and the roller assembly has such positioning stands, each with at least one cleaning device. The longitudinal stretching unit or the roller assembly is arranged between the positioning stands in such a way that the respective cleaning devices can be positioned against the functional rollers to be cleaned from opposite sides. This embodiment is particularly advantageous because, due to the small dimensions and the guiding of the film web by the roller assembly, the respective functional rollers are only accessible from one side of the cleaning device. Advantageously, two positioning stands can be used to ensure that preferably all functional rollers are cleaned, particularly partially simultaneously.

[0041] Furthermore, in design variants with two or more cleaning devices, it can be provided that only one cutting device pointing against the machine direction is provided in front of all functional rollers to be cleaned, which creates a cleaning gap in the film web, and all cleaning devices following in the machine direction engage in or reach through this cleaning gap in order to approach their respective functional rollers to be cleaned.

[0042] The problem underlying the invention is further solved by the longitudinal stretching device for monoaxially stretching the plastic film web in the machine direction. The longitudinal stretching device is particularly suitable for use in the apparatus for producing a film web, as described, for example, in one of the preceding and subsequently disclosed embodiments.

[0043] The longitudinal stretching unit comprises the roller assembly over which the film web can be transported in the machine direction. The roller assembly includes at least two functional rollers, at least two of which are designed as stretching rollers. It is provided that the stretching rollers can be driven at different circumferential speeds to stretch the film web.

[0044] Furthermore, the longitudinal stretching device includes at least one cleaning device which is designed to be attachable to and detachable from at least one of the functional rollers for cleaning that specific functional roller.

[0045] According to the invention, the cleaning device is designed such that a cleaning gap in the film web can be traversed by means of the cleaning device, which is in particular cut longitudinally into the film web by a cutting device. The variant according to the invention thus enables an advantageous type of cleaning, the advantages of which are described in the effects for the aforementioned device.

[0046] For example, a particularly advantageous embodiment provides that the longitudinal stretching device includes the cutting device. Preferably, the cutting device is arranged in the machine direction in front of the functional roller to be cleaned. Furthermore, it is advantageous that the cutting device is movable into and out of the film web perpendicular to its transverse direction, so that the film web can be cut longitudinally in such a way that a cleaning gap accessible to the cleaning device is formed within the film web.

[0047] Furthermore, it can be advantageous for the cutting device to be arranged in front of the first functional roller of the roller arrangement or, in particular, directly in front of the functional roller to be cleaned, so that the cutting device is arranged in an area between the functional roller to be cleaned and the functional roller located in front of the functional roller to be cleaned in the machine direction.

[0048] Advantageously, the longitudinal stretching device can alternatively or additionally have all the features of the longitudinal stretching device mentioned above and below, individually or in combination, in further special embodiments.

[0049] The problem underlying the invention is further solved by a method for cleaning a functional roller of a longitudinal stretching unit. In particular, the method integrates a cleaning process for cleaning one of the functional rollers of the longitudinal stretching unit into an MDO process in such a way that the ongoing production for cleaning the functional roller to be cleaned does not have to be interrupted, at least not in the sense that the film web has to be pulled off or removed from the respective functional rollers. Depending on the respective parameters of the actual MDO process, in particular the roller temperature, the transport speed of the film web, and the tension, the cleaning process can, however, also be fully integrated into the MDO process. Advantageously, the method relates to the use of one of the aforementioned embodiments of the longitudinal stretching unit.the device for producing the film web from plastic.

[0050] An exemplary MDO process with one functional roller designed as a heating roller, two functional rollers designed as stretching rollers, one functional roller designed as a cooling roller, and one functional roller designed as an annealing roller can be configured such that the plastic film web is advantageously first heated by the heating roller, then stretched monoaxially in one machine direction by the stretching rollers, and subsequently cooled by the cooling roller and tempered by the annealing roller. During the process, the film web can be guided by functional rollers designed as guide rollers, whereby the film web can advantageously be guided, deflected, and / or pressed against the respective other functional rollers by means of the guide rollers.

[0051] The method for cleaning at least one functional roller of the longitudinal stretching device involves transporting the plastic film web through the longitudinal stretching device along with the roller assembly. The roller assembly comprises at least two functional rollers, at least two of which are designed as stretching rollers.

[0052] According to the invention, at least one of the functional rollers is cleaned by means of the cleaning device by cutting the film web longitudinally using the cutting device, which is arranged in the machine direction in front of the cleaning device and can be extended and retracted into the film web. The cut creates a cleaning gap through which the cleaning device is brought to the functional roller to be cleaned.

[0053] The functional roller to be cleaned may be a guide roller and / or a heating roller and / or a stretching roller and / or a cooling roller or an annealing roller.

[0054] If the process involves cleaning two or more functional rollers, a separate cleaning device can be provided for each functional roller to be cleaned. A cutting device of the aforementioned type can also be used. In particular, the cutting device and the respective cleaning device can be designed to correspond with each other in such a way that the cutting device provides a cleaning gap in the film web through which all cleaning devices following the cutting device in the machine direction can access and position themselves against the respective functional roller to be cleaned.

[0055] In an advantageous embodiment of the method, the cutting device moves parallel to the transverse axis of the film web while it is inserted into and cutting the film web. This results in the cleaning gap being continuously cut into the film web, following the path of the cutting device. Advantageously, the cleaning device, while positioned against the functional roller to be cleaned, follows the movement of the cutting device and the path of the cleaning gap parallel to a longitudinal axis of the functional roller. For cleaning the respective functional roller, it is highly advantageous if the cleaning device remains positioned against the functional roller and within the cleaning gap while following its path.

[0056] A further advantageous embodiment of the method is based on the fact that, for cleaning the respective functional roller, the cutting device enters the film web centrally, perpendicular to its transverse extent. After the cutting device has entered the film web, it moves in a first cutting direction parallel to a transverse extent of the film web along a first cutting path, in particular at least to a first edge of the maximum transverse extent of the film web. The cutting device then moves out of the film web. The retraction of the cutting device can, in particular, consist of lifting the cutting device out of the film web or moving the cutting device, pointing in the first cutting direction, beyond the first edge of the maximum transverse extent of the film web.

[0057] It is advantageous for the cleaning device to initially move through the cleaning gap formed by the cutting device centrally to the transverse extent of the film web and to align itself with the functional roller to be cleaned. Advantageously, the cutting device then follows the movement of the cutting device and the course of the cleaning gap in the same direction as the first cutting direction, particularly up to a first axial end of a surface of the functional roller to be cleaned. Advantageously, the movement of the cleaning device is delayed relative to the cutting device, the delay depending in particular on the time lag required for the cleaning gap to move from the cutting device into the area of ​​the cleaning device.

[0058] Preferably, the cleaning device is designed to disengage from the functional roller to be cleaned after following the first cutting direction in the manner described above by a predetermined distance. If, at this point, the cleaning device is still passing through the cleaning gap, which may be the case in particular if the surface of the functional roller to be cleaned is smaller than the transverse extent of the film web and the cutting device has not cut the film web up to the first edge of the maximum transverse extent of the film web, or if the cleaning gap does not extend to the first edge of the maximum transverse extent of the film web, the cleaning device also moves out of the cleaning gap when disengaging from the functional roller to be cleaned.

[0059] According to further advantageous process steps, the cutting device is subsequently used to further clean the respective functional roller by re-entering the film web centrally, perpendicular to its transverse extent, and then proceeding in a second cutting direction parallel to a transverse extent of the film web along a second cutting path, in particular at least up to a second edge of the maximum transverse extent of the film web. It is particularly preferred that the second cutting path and the first cutting path begin at essentially the same point with respect to the transverse extent of the film web and / or preferably overlap at least partially with respect to the transverse extent of the film web.Analogous to the aforementioned process steps, the cutting device advantageously then moves out of the film web again, whereby this can expediently be done by lifting it out of the film web or by a process in the second cutting direction beyond the second edge of the maximum transverse extent of the film web.

[0060] In particular, it can be provided that the cleaning device initially engages, with a time delay corresponding to the cutting device, through the cleaning gap formed by the cutting device centrally to the transverse extent of the film web and positions itself against the functional roller to be cleaned. Preferably, the cleaning device then follows the movement of the cutting device and the course of the cleaning gap in the same direction as the second cutting direction. Preferably, the cleaning device follows the movement of the cutting device or the course of the cleaning gap up to a second axial end of the surface of the functional roller to be cleaned.

[0061] Advantageously, the cleaning device moves out of the cleaning gap and / or moves away from the functional roller to be cleaned after it has been moved in the manner described above by a predetermined amount in the second cutting direction.

[0062] It is particularly within the scope of the invention that the second cutting direction is opposite to the first cutting direction and that the second edge of the maximum transverse extent of the film web is arranged opposite to the first edge of the maximum transverse extent of the film web. Likewise, it is advantageously within the scope of the invention that the second axial end of the surface to be cleaned is arranged opposite to the first axial end of the surface to be cleaned of the functional roller to be cleaned.

[0063] Preferably, “centrally to the transverse extent of the film web” within the meaning of the invention refers to an area of ​​the film web which extends relative to the transverse extent of the film web between the first edge of the maximum transverse extent of the film web and the second edge of the maximum transverse extent of the film web.

[0064] The area "centered to the transverse extent of the film web" must be selected, particularly depending on the properties of the film web (e.g., web thickness and material) and the operating parameters of the longitudinal stretching device or the device for producing the film web (e.g., web tension), such that the area is spaced from the first and second edges of the maximum transverse extent of the film web in such a way that, when the cutting device is inserted into and cuts the film web, and subsequently moves in the respective first or second cutting direction parallel to the transverse extent of the film web, the web tension on the film web does not cause the film web to tear during transport in the machine direction. Thus, a remaining edge section between the area "centered to the transverse extent of the film web" and the respective first or second cutting direction must be ensured.The second edge of the maximum transverse elongation of the film web should be considered the minimum required to reliably transport the film web through the rest of the longitudinal stretching unit or through the film web production device. In practice, it has proven effective for the respective edge sections to be at least 40 to 50 cm, depending on the material properties and operating parameters.

[0065] Preferably, “central to the transverse extent of the film web” is to be defined as the center of the transverse extent of the film web with a tolerance deviation of up to 30%, in particular up to 15%, and most advantageously up to 5% of the maximum transverse extent of the film web.

[0066] Particularly preferred is the interpretation of "center to the transverse extent of the film web" as the center of the transverse extent of the film web such that the edge section between the area "center to the transverse extent of the film web" and the first edge of the maximum transverse extent of the film web and the edge section between the area "center to the transverse extent of the film web" and the second edge of the maximum transverse extent of the film web are of the same size, which leads to a particularly high level of process reliability.

[0067] Preferably, the inventive method can be supported by the fact that at least the cleaning device, as described above, is positioned against and disengaged from the functional roller to be cleaned by means of at least one electric cleaning device motor and is moved parallel to the longitudinal axis of the functional roller to be cleaned. Likewise, it is within the scope of the invention that the cutting device is inserted into and removed from the film web by means of at least one electric cutting device motor and / or moved parallel to the transverse extent of the film web. The respective motors simplify the operation of the longitudinal stretching device, reduce the required installation space, and increase operational reliability.Accordingly, it is advisable to provide that at least one electric cleaning device motor, in particular the cutting device motor, is controlled by the control unit.

[0068] Furthermore, a particular embodiment of the method is based on the fact that the position of the cleaning gap in the film web is detected by means of a sensor connected to the control unit in a section in front of the functional roller to be cleaned, as viewed in the machine direction. It is advantageously provided that, based on the position of the cleaning gap in the film web, the cleaning device motor is controlled in such a way that the cleaning device follows the position or path of the cleaning gap on the film web. The embodiment of the sensor or the sensor-based method has already been described above. Depending on the application, it may also be advantageous to connect the control unit to more than one sensor unit for detecting the cleaning gap.

[0069] The sensor unit can also be used to support the process in such a way that, upon detecting the beginning of the cleaning gap, the cleaning device moves across the entire cleaning gap towards the functional roller to be cleaned, and upon detecting the end of the cleaning gap, it moves away from the functional roller to be cleaned. In particular, this allows the process to be carried out automatically, regardless of how the cleaning gap is introduced, and especially regardless of whether the cutting device is connected to the control unit or not.

[0070] Particularly when the cutting device is connected to the control unit, an advantageous variant of the method provides that the movement of the cleaning device is synchronized with the movement of the cutting device in such a way that the movement of the cleaning device is calculated as a function of the movement of the cutting device. Advantageously, the movement of the cleaning device corresponds to the movement of the cutting device. To implement this variant of the method, it is particularly necessary to calculate a dead time by determining the duration that a specific point on the film web requires to be transported from the cutting device to the cleaning device.The method is preferably adapted such that a dead time is provided between the movement of the cutting device and the movement of the cleaning device, or that the cleaning device follows the movement of the cutting device with a time delay corresponding to the dead time.

[0071] Further advantages, features, and details of the invention will become apparent from the following description, in which various exemplary embodiments are explained in detail with reference to the figures. The features mentioned in the claims and in the description can each be essential to the invention individually or in any combination thereof. Within the scope of the entire disclosure, features and details described in connection with the method according to the invention naturally also apply in connection with the apparatus and the longitudinal stretching device according to the invention, and vice versa, so that the disclosure always makes, or can make, reciprocal references to the individual aspects of the invention.

[0072] The individual figures show: 1. A schematic representation of a device for producing a film web made of plastic, 2. a schematic side view of a longitudinal stretching device for stretching a sheet of foil, 3. a schematic representation in the direction of view A according to Fig. 2 on the longitudinal stretching device acc. Fig. 2, 4. a schematic sectional view along a transverse dimension of the foil web in area B according to Fig. 2 a cleaning gap of the foil web extending through to the cleaning functional roller attached cleaning device, 5. a schematic representation of the path of a cutting device and a cleaning device relative to the film web, 6. a schematic representation of a method for operating the longitudinal stretching device, 7. a schematic representation of another method for operating the longitudinal stretching device 8. a schematic representation of another method for operating the longitudinal stretching device and 9. a schematic representation of another method for operating the longitudinal stretching device.

[0073] In the various figures of the drawing, identical parts are always labelled with the same reference symbols.

[0074] For the following description, it is claimed that the invention is not limited to the exemplary embodiments and not to all or several features of the described combinations of features, but that each individual partial feature of the exemplary embodiment(s) is also significant for the subject matter of the invention independently of all other partial features described in connection therewith and also in combination with any features of another exemplary embodiment.

[0075] Fig. Figure 1 shows a device 200 for producing a film web 2 made of plastic, wherein the in Fig.Figure 1 shows a device designed as an exemplary blown film line. It is expressly claimed that all features mentioned in the following exemplary embodiments, unless expressly indicated, also apply to other devices 200 for the production of a film from plastic, for example, cast film lines.

[0076] As in Fig. As shown in Figure 1, the device 200 initially comprises at least one extrusion device 202, by means of which, for example, plastic in granular form can be plasticized to a plastic melt 206.

[0077] The plastic melt 206 thus produced can advantageously be fed to an extrusion die or a die head 204 via a line. In the advantageous embodiment as a blown film system, the plastic melt 206 can be transferred into a film tube by means of the die head 204, in that the plastic melt 206 can be conveyed from an outlet, in particular annular, in a take-off direction Z. Furthermore, the plastic melt 206 and the resulting film web 2 can be pulled off in the take-off direction Z with the assistance of a take-off roller 214.

[0078] After the polymer melt 206 exits the nozzle head 204, it is in the form of a foil tube. This foil tube is initially in a soft or deformable state and is preferably inflated from the inside by a slight overpressure such that it is enlarged to a diameter with a circular cross-section within an optional calibration device, in particular a calibration basket 208. The foil tube is solidified, in particular, by an annular temperature control device 210 surrounding the foil tube, which, due to its annular shape, is often also referred to as a cooling ring.

[0079] After passing through the calibration device or calibration basket 208, the film tube expediently enters the working area of ​​a flattening unit 212, in which the film tube, which at this point is circular, is transformed into an elliptical cross-section with increasing eccentricity, until it finally enters the influence area of ​​the take-off rollers of the take-off unit 214, which transform the film tube into a double-layered, laterally connected plastic web 207.

[0080] The flattening unit 212 is preferably rotatably arranged, the axis of rotation being essentially aligned with a hose axis L which is in Fig. 1 is indicated by a dashed line. The rotatability of the flattening unit 212 is shown by an arrow about the hose axis L.

[0081] The in Fig.Figure 1, an advantageous variant as a blown film system, further shows a preferred reversing device 216, which has the task of guiding the flattened film tube or the double-layered film web 207 from the flattening unit 212 to a stationary roller, in particular without causing damage.

[0082] The device 200 for producing a film web 2 made of plastic further comprises a longitudinal stretching device 1 for monoaxial stretching of the film web 2 in a machine direction M.

[0083] The longitudinal stretching device 1 is arranged in particular downstream of the reversing device 216 or in the machine direction M behind the reversing device 216.

[0084] Preferably, a layer cutting device 22.1 is positioned upstream of the longitudinal stretching device 1, or in the machine direction M between the longitudinal stretching device 1 and the reversing device 216. The layer cutting device 22.1 can be designed such that one or two edges of the flattened double-layer film web 207 can be opened or cut off. Furthermore, a separating device can be provided to separate the double-layer film web 207 into one or more single-layer film webs 2.

[0085] The longitudinal stretching device 1 is particularly useful in the Fig. 2 and Fig. Figure 3 shows the film web 2 being stretched within the longitudinal stretching device 1, in particular in the section shown. Fig.In the embodiment shown in Figure 3, the film web is transported in the machine direction M by a roller arrangement comprising at least two functional rollers. It is provided that at least two functional rollers are designed as stretching rollers 6 and can be driven, or are driven, at different circumferential speeds to stretch the film web 2. Furthermore, it is provided that the longitudinal stretching device 1 has at least one roller assembly, particularly in the Fig. 2 and Fig. 3 has a cleaning device 14 shown, which is designed to be coupled to and decoupled from at least one of the functional rollers for cleaning the respective functional roller 3.

[0086] Fig. Figure 2 shows a longitudinal stretching device 1, which can be integrated, in particular, into a device 200 for producing film webs 2 made of plastic. With the longitudinal stretching device 1, a film web 2 can be stretched in a machine direction M.

[0087] Fig. Figure 2 shows a particular embodiment of the invention, in which the roller arrangement comprises, for example, functional rollers configured as guide rollers 10, 12, a functional roller configured as a heating roller 4 for heating the film web 2, at least two functional rollers configured as stretching rollers 6, and at least one functional roller configured as a cooling roller 8 for cooling the film web 2 and / or a functional roller configured as an annealing roller 8 for tempering the film web 2. The number of each functional roller can, however, be varied by means of the figures shown in Figure 2. Fig. The design shown in section 2 goes beyond this. To illustrate this, the foil strip 2 is in Fig. 2 shown as examples after the heating roller 4, after the last stretching roller 6 in machine direction M and after the cooling or annealing roller 8, which implies optional further functional rollers between the functional rollers shown.

[0088] The functional rollers designed as guide rollers can be configured, in particular, as pressure rollers 10 for pressing the film web 2 against another functional roller, or expediently as transport rollers 12, in particular for guiding and / or deflecting the film web 2. The pressure rollers 10 are expediently only in Fig. 2 shown.

[0089] The longitudinal stretching of the film web 2 is carried out in a manner known per se, in particular by driving the stretching rollers 6 at a different rotational speed, wherein a difference in rotational speed or different circumferential speeds of the respective stretching rollers 6 or a difference in diameter of the respective stretching rollers 6 causes a stretching of the film web 2 when the film web 2 is transported in the machine direction M.

[0090] The Fig.Figures 2 to 4 show an advantageous embodiment in which the longitudinal stretching device 1 comprises only one cleaning device 14 for cleaning a functional roller, wherein the functional roller 3 to be cleaned is, in this example, one of the stretching rollers 6. It is within the scope of the invention that further and / or other functional rollers can also be cleaned by means of a cleaning device 14, in particular one cleaning device 14 each.

[0091] It can also be provided that the cleaning device 14 is mounted on a motor-controlled, in particular electric motor-controlled, positioning frame so as to be movable relative to the functional rollers in two or more cleaning positions, such that the cleaning device 14 is arranged in each cleaning position to clean a different functional roller.

[0092] Since the functional roller 3 to be cleaned is driven or can be driven in a rotating manner during operation of the longitudinal stretching device 1, particularly via a corresponding roller drive, a special embodiment provides that the cleaning device 14 comprises a contact block 16, as exemplified in Fig.Figure 4 illustrates this. The contact block 16 has a cleaning surface 18 which, at least when the contact block is positioned against the functional roller 3 to be cleaned, faces the functional roller 3. In this position, the contact block 16, with its cleaning surface 18, rubs against a surface 20 of the functional roller 3 to be cleaned, thus effecting contact cleaning. Since the roller cleaning can be carried out during the operation of the longitudinal stretching device 1 and the respective functional roller is driven in rotation, the cleaning device 14 itself does not need to perform a cleaning movement for contact cleaning.However, special variants not shown additionally provide that the cleaning device 14 comprises a rotatably driven / powered cleaning roller and / or a cleaning belt guided and driven around a roller assembly instead of a contact block.

[0093] The Fig. 2 and Fig. Figure 3 shows that, according to the invention, a cutting device 22 is provided in front of the cleaning device 14, viewed in the machine direction M. The cutting device 22 is designed such that, as shown in particular in Figure 3, it is designed to cut the cutting device 22 in a way that allows the cutting device 22 to cut the cutting device 22 in the direction of the machine M ... Fig. Figure 3 shows that the cutting device 22 can be inserted into and removed from the film web 2 perpendicular to a transverse extension 24 of the film web 2. By means of the cutting device 22, the film web 2 can thus be cut longitudinally in such a way that a cleaning gap 26, through which the cleaning device 14 can penetrate, can be formed or is formed. In particular, in the Fig. 3 and Fig.Figure 4 shows how the cleaning device 14 positions itself against the functional roller 3 to be cleaned, in particular the stretching roller 6, and thereby penetrates the cleaning gap 26.

[0094] A particular variant of the device 200 provides that the cutting device 22, viewed in the machine direction M, is arranged in front of or inside the take-up 214. Advantageously, the optional layer cutting device, as may be provided particularly in blow molding systems, can be designed as a cutting device 22 for providing the cleaning gap 26. For illustration, the layer cutting device, which also acts as a cutting device 22, is shown in Fig. 1 marked with 22.1.

[0095] One variant, not shown, provides that the cutting device 22 is arranged in an area between the pull-off 214 and the longitudinal stretching device 1, following the machine direction M.

[0096] It may be expediently provided that the longitudinal stretching device 1 provides the cutting device 22 for the provision of the cleaning gap 26, as in the Fig. 2 and Fig. The cutting device 22 is preferably arranged upstream of the first functional roller, as shown in the machine direction M. The cutting device is shown by way of example in Fig. 2 in front of the at least one heating roller 4 and the stretching rollers 6 and the at least one cooling roller 8 or the at least one annealing roller 8. It can also be provided that the cutting device 22 is arranged directly in front of the functional roller 3 to be cleaned such that the cutting device 22 is arranged in an area between the functional roller 3 to be cleaned and the functional roller arranged in front of the functional roller 3 to be cleaned in the machine direction M.

[0097] An advantageous effect has also been shown in a variant not shown, in which the cleaning device 14 and the cutting device 22 are arranged directly adjacent to each other in the machine direction M on a common bearing unit and / or are designed as a common cutting and cleaning device.

[0098] Furthermore, the cutting device 22 can be arranged between two guide rollers designed as transport rollers 12, relative to the machine direction M. The guide rollers 12 ensure reliable guidance of the film web 2, allowing the cutting device 22 to move reliably into and out of the film web 2. In particular, the cutting behavior of the film web 2, or its behavior during the insertion and retraction of the cutting device 22, can be influenced and adapted to specific applications by varying the distance between the two guide rollers 12, between which the cutting device 22 is arranged. For example, the guide rollers 12 can be designed to be radially displaceable about their respective longitudinal axes, as shown by arrows 27 in the figure. Fig. 2.

[0099] In an alternative configuration (not shown), the cutting device 22 can also be arranged in front of the functional rollers designed as guide rollers, viewed in the machine direction M. This configuration can be advantageous if the film web 2 is already fed to the longitudinal stretching device 1 in a suitable manner. For example, the cutting device 22 is arranged in the machine direction M in an area between the take-off unit 214 and the longitudinal stretching device 1.

[0100] The in Fig. The 3 non-visible elements of the cutting device 22 or the elements of the cutting device 22 that are concealed or covered by the film web 2 during the operation of the longitudinal stretching device 1 are marked with dashed lines for better understanding.

[0101] In practice, it has proven advantageous if the cutting device 22 is designed to pivot about a rotational axis for entering and exiting the film web 2. Alternatively or additionally, it can also be provided that the cutting device 22 is movable along a linear travel path into and out of the film web 2. For illustration, the following are shown in Fig. Figure 2 shows both the pivoting movement 28 and the linear movement 30. In particular, it can be provided that the cutting device 22 has at least one, in particular electric, cutting device motor for moving in and out of the film web 2.

[0102] Similarly, the cleaning device 14 may be designed such that it is pivotable about a rotary axis 32 for positioning itself against and disengaging from the functional roller 3 to be cleaned, and / or can move along a linear travel path 34 for positioning and disengagement. The two alternative or complementary variants are described in Fig. 2 shown. In particular, it can be provided that the cleaning device 14 has at least one, preferably electric, cleaning device motor for switching on and off to and from the functional roller 3 to be cleaned.

[0103] According to the presentation in the Fig. 2 and Fig. 3 An advantageous embodiment is based on the fact that the cutting device 22 has a knife element 36 for slit-like cutting of the film web 2.

[0104] Furthermore, it is particularly advantageous if a slitting device in the machine direction M is designed behind the cutting device 22 in such a way that the cut edges resulting from cutting are widened in directions pointing away from each other parallel to the transverse extension 24 of the film web 2.

[0105] The slitting device can in particular be designed as an independent device which is subordinate to the cutting device 22 and in particular follows a movement of the cutting device 22 parallel to the transverse extension 24 of the film web 2.

[0106] Variants in which the splitting device is integrated into the cutting device 22 and / or the cleaning device 14 are particularly advantageous.

[0107] Fig.Figure 3 shows by way of example that the splitting device is advantageously designed as a folding device 38 and is expediently arranged behind the knife element 36 when viewed in the machine direction M. The folding device 38 is preferably designed such that it folds the cut edges in two reversible folding directions 40. It is particularly advantageous that the folding action reduces the in Fig. The 3 to 5 double-layered film web edge sections 42 shown are formed, which advantageously limit the cleaning gap 26. Additionally, pressure rollers can be provided which press the double-layered film web edge sections against each other. In particular, the pressure rollers exert a pressure on a fold formed during folding of the double-layered film web edge sections 42.

[0108] Further variants, not shown, may provide that the slitting device and the cutting device 22 and / or the cleaning device 14 are arranged directly adjacent to each other in the machine direction M on a common bearing unit and / or are designed as a single slitting, cutting, and / or cleaning device. In particular, this combined embodiment may be pivotable about a rotary axis to move towards and away from the functional roller 3 to be cleaned, or to cut into and out of the film web 2. Alternatively or additionally, the combined embodiment may be movable along a linear travel path for approaching and moving away from the functional roller 3 or the film web 2 to be cleaned. The two alternative or complementary variants are shown in Figure 1.In particular, the combined embodiment may include at least one, preferably electric, motor for moving to and from the functional roller 3 to be cleaned or for moving in and out of the film web 2.

[0109] It can also be advantageous for the cutting device 22 to be designed with two parallel blade elements for cutting a strip of film from the film web 2. The film strip can expediently be separated from the film web 2 by means of a discharge device. The strip-shaped gap remaining in the film web 2 represents a particularly advantageous variant of the cleaning gap 26, which can be designed, in particular without a gap device for widening the film web edge sections 42, such that the cleaning gap 26 can have a size advantageous for the cleaning device 14.

[0110] Alternatively, a threading aid can also be provided which supports the insertion of the cleaning device 14 into the cleaning gap 26 when the cleaning device 14 is positioned against the functional roller 3 to be cleaned and preferably guides the film web 2 around the cleaning device 14.

[0111] In particular, it is provided that the cutting device 22 is movable parallel to the transverse extent 24 of the film web 2, see arrows L in Fig. 3 and that the cleaning device 14 can be moved analogously parallel to a longitudinal axis 46 of the functional roller 3 to be cleaned, see arrows 48 in Fig.3. Advantageously, to provide these respective movements, the cutting device 22 and the cleaning device 14 may each be mounted in a guide rail 50, 52, in which they are preferably motor-driven. In particular, the cleaning device 14 may be mounted in a cleaning rail 50 and be manually and / or motor-driven. Alternatively or additionally, the cutting device may be mounted in a cutting rail 52 and be manually and / or motor-driven. The cutting rail 52 and the cleaning rail 50 are illustrated by way of example in Fig. 3 shown.

[0112] Furthermore, it has proven particularly advantageous in practice that, for moving the cutting device 22 parallel to the transverse extension 24 of the film web 2, the cutting device 22 can be moved by means of at least one advantageous, preferably electric, cutting device motor or at least one further, in particular electric, cutting device motor. Likewise, for moving the cleaning device 14 parallel to the longitudinal axis 46 of the functional roller 3 to be cleaned, it is very advantageous if, according to an optional embodiment, the cleaning device 14 can be moved by means of at least one advantageous, preferably electric, cleaning device motor or at least one further, in particular electric, cleaning device motor.

[0113] Preferably, the respective drives of the cutting device 22 and the cleaning device 14, in particular the respective electric cleaning device motor(s) and / or the cutting device motor(s), can be controlled by means of a control unit, which is expediently connected to the respective cleaning device 14 or cutting device 22. The respective drives of the cleaning device 14 or the cutting device 22, as well as the control unit, are located in the Fig. Numbers 1 to 5 are not shown.

[0114] In particular, it can also be provided that the combined cutting and cleaning device or the common bearing unit is movable via the cleaning rail 50, in particular by motor, preferably in the manner described above, analogous to the aforementioned embodiments.

[0115] According to an advantageous embodiment of the invention, the longitudinal stretching device 1 and / or the control unit comprises a sensor unit 54 and / or is connected / connectable to a sensor unit 54. The sensor unit 54 is advantageously configured to detect the position of the cleaning gap 26 in the film web 2 in an area viewed in the machine direction M in front of the functional roller 3 to be cleaned. Fig.Figure 2 shows, by way of example, an optical detection unit 54 designed as a sensor unit 54, in particular a camera, which, viewed in the machine direction M, is arranged such that it monitors an area in front of the functional roller 3 to be cleaned or in front of the cleaning device 14. In combination with the sensor unit 54, the control unit is preferably configured to control the cleaning device drive depending on the position of the cleaning gap 26 in the film web 2. In particular, this allows the control unit to be triggered in the event of a displacement of the cleaning gap 26, especially relative to the transverse extent 24 of the film web 2, as shown in Figure 2. Fig. 5 shown, the cleaning device 14 follows the course of the cleaning gap 26, regardless of whether the movement of the cutting device 22 is controlled and / or monitored manually or automatically.

[0116] According to the invention, the longitudinal stretching device 1 is also for the monoaxial stretching of the plastic film web in the machine direction M. Advantageously, this longitudinal stretching device can be integrated into the device 200 for the production of plastic film webs 2, in particular into a device 200 of the type described in this description. As stated above, the longitudinal stretching device 1 comprises at least the roller arrangement with two functional rollers designed as stretching rollers 6, wherein the film web 2 can be conveyed in the machine direction M by means of the roller arrangement. For stretching the film web 2, the stretching rollers 6 can be driven at different circumferential speeds. Furthermore, the longitudinal stretching device 1 includes the described cleaning device 14, which is designed to be connected to and disconnected from the respective functional roller 3 for cleaning at least one of the functional rollers.According to the invention, the cleaning device 14 is also designed such that a cleaning gap 26 extending longitudinally in the film web 2 can be accessed by means of the cleaning device 14. Preferably, the cleaning gap is cut longitudinally into the film web 2 by means of the cutting device 22.

[0117] The longitudinal stretching device 1 may advantageously include all features, in particular a cutting device 22 and / or a positioning frame and / or a splitting and cutting device and / or a cleaning device and / or a cutting and cleaning device, which are disclosed in this description with respect to the longitudinal stretching device 1.

[0118] According to the invention, the cleaning device 14 itself can also be designed, according to one of the embodiments disclosed within the scope of this description, for retrofitting a longitudinal stretching device 1 and / or a device 200 for producing film webs 2 made of plastic.

[0119] For cleaning 100 at least one of the functional rollers 3 of the longitudinal stretching device 1, in particular of the longitudinal stretching device 1 according to the invention or an optional variant thereof, it is provided that the film web 2 is first guided through the longitudinal stretching device 1 by means of the at least two functional rollers of the roller arrangement designed as stretching rollers 6. It can optionally be provided that in a first step the heating roller 4 is heated or cooled, see step 102 in Fig. 6.

[0120] The film web 2 is then guided in the machine direction M by means of at least two stretching rollers 6, see step 104 in Fig.6. Optionally, stretching can also be carried out, provided that the operating or stretching parameters allow this in conjunction with the properties of the film web.

[0121] It may be advantageous to provide that the film web 2 is subsequently cooled by means of at least one cooling roller 8 and / or tempered by means of at least one annealing roller 8, see step 106 in Fig. 6.

[0122] While the longitudinal stretching device 1 is being operated, the film web 2 is guided by means of the guide rollers 10, 12.

[0123] According to the invention, at least one of the functional rollers 3 is cleaned by means of the cutting device 22, which can be inserted into and withdrawn from the film web 2, cutting the film web 2 longitudinally by the cutting device 22 entering the film web 2 so that the cleaning gap 26 is formed, see step 108 in Fig. 6.

[0124] Furthermore, process step 110 provides that the cleaning device 14, in particular in the aforementioned manner, is positioned so that the cleaning gap 26 extends completely through the cleaning gap 26 to the functional roller 3 to be cleaned. Fig. 6 is in accordance with the in Fig. Figure 2 of the embodiment of the longitudinal stretching device 1 shows that the cleaning gap 26 is created by the cutting device 22 before the film web 2 is heated by the at least one heating roller 4. In practice, however, it is more important that the cleaning gap 26 is provided in the machine direction M in front of the cleaning device 14 or in front of the functional roller 3 to be cleaned in a suitable manner by the cutting device 22, so that a process sequence in Fig. 6. A different sequence is found within the scope of the invention.

[0125] Optionally, the method 100 can be supplemented in particular by moving the cutting device 22 parallel to the transverse extent 24 of the film web 2 while the cutting device 22 is inserted into and cutting the film web 2, see step 112 in Fig. 6. The movement of the cutting device 22 can be carried out in one of the aforementioned ways. This variant results in the cleaning gap 26 being continuously cut into the film web 2 along the cutting device 22. Fig.Figure 5 schematically shows an advantageous cutting path 56 extending longitudinally through the film web 2 when the cutting device 22 is moved in a transverse direction 24 of the film web 2 during transport of the film web 2 in the machine direction M. For particularly advantageous cleaning of the functional roller 3 to be cleaned, an advantageous process step 114 provides that the cleaning device 14, while positioned against the functional roller 3 to be cleaned, follows the movement of the cutting device 22 and the path R of the cleaning gap 26 parallel to the longitudinal axis 46 of the functional roller 3 to be cleaned, such that the cleaning device 14 is always in engagement with the respective functional roller and, as shown in Figure 5, Fig. 4 shown, is arranged within the cleaning gap 26.

[0126] Since steps 108 to 114 can be carried out essentially in parallel with steps 102 to 106, or since production does not need to be shut down to carry out steps 108 to 114, steps 102 to 106 are included in Fig. 6 shown in parallel to steps 108 to 114.

[0127] Referring to the schematic representation in Fig. 5 This results in a cutting path 56 provided by the cutting device 22, which corresponds to the path R of the cleaning gap 26 in the film web 2, being essentially identical with respect to the film web 2 to a cleaning path 58 which the cleaning device 14 travels along the cleaning gap 26 relative to the film web 2.

[0128] In the advantageous embodiment according to Fig. 5 is expediently provided that in one step 116, see Fig.7, the cutting device 22 initially enters the film web 2 centrally to the transverse extent 24 of the film web 2 and in a step 118 moves in a first cutting direction S1 parallel to a transverse extent 24 of the film web 2 along a first cutting path. Fig. Figure 5 shows an example of a center line 60 of the film web 2. Advantageously, the cutting device 22 moves up to a first edge 62 of the maximum transverse extent 24 of the film web 2, shown in particular in Figure 5. Fig. 5.

[0129] The cutting device 22 then moves, see step 120 in Fig. 7, from the film web 2. This can be done in particular by moving the respective cutting device 22 parallel to the transverse extent 24 of the film web 2 beyond the respective edge 62 of the film web 2, see Fig.5, and / or by spacing the cutting device 22 perpendicular to the machine direction M from the film web 2 such that a gap is formed between a surface plane of the film web 2 facing the cutting device 22 and the cutting device 22.

[0130] Advantageously, and in temporal overlap with the provision of the cleaning gap 26, the method 100 preferably provides that the cleaning device 14 first, with a time delay corresponding to the respective movement of the cutting device 22, penetrates the cleaning gap 26 created by the cutting device 22 in the center of the film web 2 and positions itself against the functional roller 3 to be cleaned, see step 122 in Fig. 7. It is then provided that the cleaning device 14 follows the movement of the cutting device 22 and the course of the cleaning gap 26 in the same direction as the first cutting direction S1 and subsequently, see step 124 in Fig.7, which emerges from the cleaning gap 26, see Fig. 5, and / or moves away from the functional roller 3 to be cleaned.

[0131] Advantageously, the course R of the cleaning gap 26 is adapted by means of the cutting device 22 so that the cleaning device 14, when it follows the course R of the cleaning gap 26, can move through the cleaning gap 26 to a first axial end of the surface 20 of the functional roller 3 to be cleaned.

[0132] To ensure complete cleaning of the functional roller 3, a second cutting and cleaning of the functional roller 3 to be cleaned is regularly advantageous.

[0133] In particular, in this case, the aforementioned procedure 100 is followed by a return of the cutting device 22 and the cleaning device 14 to a central position relative to the transverse extent 24 of the film web 2, see step 126 in Fig. 7. For this purpose, the cleaning device 14 and the cutting device 22 are first positioned perpendicular to the machine direction M from the film web 2 such that a gap is formed between the surface plane of the film web 2 facing the cleaning device 14 and the cutting device 22, respectively, and the cutting device 22. Subsequently, the cutting device 22 can be moved parallel to the transverse dimension 24 and the cleaning device 14 parallel to the longitudinal axis 46 of the functional roller 3 to be cleaned into a substantially central position relative to the transverse dimension 24 of the film web 2.

[0134] For further cleaning, it is preferably provided that the cutting device 22 repeatedly enters the film web 2 centrally to the transverse extent 24 of the film web 2 in process step 128 and moves in a second cutting direction S2 parallel to the transverse extent 24 of the film web 2 along a second cutting path and opposite to the first cutting direction S1, in particular at least up to a second edge 64 of the maximum transverse extent 24 of the film web 2, see step 130 in Fig. 7, and then exits from foil lane 2, see step 132 in Fig. 7. The second edge 64 of the maximum transverse extent 24 of the foil web 2 is, in particular, as shown in Fig. Figure 5 shows the process steps 128 to 132 arranged opposite the first edge 62 of the maximum transverse extent 24 of the film web 2. In particular, it is provided that the process steps 128 to 132 correspond in their sequence and their possible implementations to the preceding process steps 116 to 120, with the difference that the second cutting direction S2 and thus also the course R of the cleaning gap 26 and the cutting path 56 point in opposite directions compared to process steps 116 to 120.

[0135] For a particularly advantageous cleaning of the functional roller 3, it is especially preferred that the second cutting section and the first cutting section begin at essentially the same point relative to the transverse extent 24 of the film web 2 or preferably overlap at least partially relative to the transverse extent 24 of the film web 3.

[0136] Preferably, process steps 134 and 136 are provided analogously to process steps 122 and 124. Process step 134 expediently provides that the cleaning device 14, corresponding to the movement of the cutting device 22 according to process step 122, first engages the cleaning gap 26 created by the cutting device 22 in the center of the film web 2 with a time delay and positions itself against the functional roller 3 to be cleaned. Subsequently, the cleaning device 14 is provided to follow the movement of the cutting device 22 and the path R of the cleaning gap 26 in the same direction as the second cutting direction S2 and then, in process step 136, moves out of the cleaning gap 26 and / or moves away from the functional roller 3 to be cleaned.Process steps 134 and 136 are also preferably designed such that the cutting device 22 and the cleaning device 14 correspond to each other in such a way that the cleaning gap 26 is provided at least up to a second axial end of the surface 20 to be cleaned of the functional roller 3, opposite the first axial end of the surface 20 to be cleaned. This allows the cleaning device 14 to follow the cleaning gap 26 up to this axial end of the surface 20 to be cleaned. In particular, it is provided that the process steps correspond in their sequence and their possible implementations to the preceding process steps 122 and 124, with the difference that the second cutting direction S2, and thus also the path R of the cleaning gap 26, the cutting path 56, and the cleaning path 58 point in opposite directions compared to process steps 122 and 124 (see figure). Fig. 5.

[0137] In Fig. In section 5, the aforementioned process steps 116 to 136 are illustrated using an exemplary film web 2. Process steps 116 to 136 create two cleaning gaps in the film web 2, arranged one after the other in the longitudinal direction of the film web 2. The cutting paths 56 forming the cleaning gaps 26 each originate from an entry point into the film web 2 that is centered relative to the transverse dimension 24 of the film web 2 and proceed parallel to the transverse dimension 24 of the film web 2 in a first or second cutting direction S2. As a result, the cleaning device 14, following the two cleaning gaps, can contact and clean the functional roller 3 to be cleaned along its entire longitudinal axis 46, or the surface 20 to be cleaned, by means of the two successive cutting or cleaning paths 58.

[0138] It is particularly within the scope of the invention that the displacement of the cutting device 22 parallel to the transverse extension 24 of the film web 2 and / or the insertion or removal of the cutting device 22 into or out of the film web 2 and / or the displacement of the cleaning device 14 axially to the functional roller 3 to be cleaned and / or the connection or disconnection of the cleaning device 14 to the functional roller 3 to be cleaned is carried out manually and / or by hand and / or by means of the at least one cleaning device motor or the at least one cutting device motor.

[0139] The respective motors are controlled by the control unit either through manual input via the remote control or through a control program running in the control unit.

[0140] In Fig. Figure 8 presents a further supplementary or alternative variant for carrying out procedure 100 for operating the longitudinal stretching device 1. Accordingly, it is self-evident that procedure 100, in particular the one described in Figure 8, is used in accordance with the above provisions. Fig. The methods shown in Figures 6 and / or 7 can be carried out and / or improved using the sensor unit 54, in particular the optical detection unit 54, to detect the position of the cleaning gap 26 by detecting the position of the cleaning gap 26 in the film web 2 in the area viewed in the machine direction M in front of the functional roller 3 to be cleaned, and by controlling the cleaning device motor by the control unit depending on the position of the cleaning gap 26 and / or the beginning of the cleaning gap 26 and / or the end of the cleaning gap 26 in the film web 2. This variant is particularly suitable in Fig. Figure 8 shows that, depending on the position of the cleaning gap 26 in the film web 2, the cleaning device motor is controlled in such a way that the cleaning device 14 follows the position or the course R of the cleaning gap 26 on the film web 2.

[0141] The in Fig. The method variant shown in Figure 8 provides that a cleaning gap 26 is first provided by inserting the cutting device 22 into the film web 2 and thereby beginning to cut the film web 2 longitudinally, see step 138 in Fig. 8.

[0142] The control unit uses the sensor unit 54 to conveniently detect the beginning of the cleaning gap 26 and the position of the beginning of the cleaning gap 26 relative to the transverse extent 24 of the film web 2, see step 140 in Fig. 8.

[0143] The control unit controls at least one cleaning device motor in such a way that the cleaning device 14 moves parallel to the longitudinal axis 46 of the cleaning roller to the position of the beginning of the cleaning gap 26 and positions itself against the functional roller 3 to be cleaned through the cleaning gap 26, see step 142 in Fig. 8.

[0144] Preferably, the position of the cleaning gap 26 in the film web 2 is continuously detected or monitored by means of the control unit and the sensor unit 54, and based on the position of the cleaning gap 26 in the film web 2, the at least one cleaning device motor is controlled by the control unit in such a way that the cleaning device 14 follows the position or the path R of the cleaning gap 26 on the film web 2, see step 144 in Fig. 8.

[0145] In particular, when the cutting device 22 moves out of the film web 2, the end of the cleaning gap 26 in the film web 2 is defined. Advantageously, the control unit detects the end of the cleaning gap 26 by means of the sensor unit 54 and, via the control unit, controls the at least one cleaning device motor in such a way that it moves the cleaning device 14 away from the functional roller 3 to be cleaned before the end of the cleaning gap 26 reaches the cleaning device 14, see step 146 in Fig. 8.

[0146] A supplementary or alternative method variant provides that the cutting device 22 and the cleaning device 14 are connected to the control unit, thus synchronizing the movement of the cleaning device 14 with the movement of the cutting device 22. This variant is exemplified in Fig. 9 shown. For this purpose, it is advantageous that the movement of the cutting device 22, in particular the entry and exit into the film web 2 and / or the procedure parallel to the transverse extent 24 of the film web 2, can be determined or is determined, see step 147 in Fig. 9. This can expediently be achieved using sensors, in particular optical detection devices, e.g., image recognition or laser distance measuring devices. According to a particularly preferred supplementary or alternative embodiment, the movement of the cutting device 22 can be determined by the control unit determining the relative movement of the cutting device 22 via the at least one cutting device motor.

[0147] As in Fig. As shown in Figure 9, it is advantageous if the respective movement of the cleaning device 14 is synchronized with the movement of the cutting device 22 such that control signals for the at least one cleaning device motor for the movement of the cleaning device 14 are calculated by means of the control unit as a function of the movement of the cutting device 22, see step 148 in Fig. 9. Advantageously, the cleaning device motor is controlled by the control unit with the calculated control signals such that the cleaning device 14 follows the path R of the cleaning gap 26 on the film web 2, see step 150 in Fig. 9. In particular, in a special variant of the method, control signals can also be calculated based on the movement of the cutting device 22 by means of the control unit, by means of which the cleaning device 14 is positioned against the functional roller 3 to be cleaned and is moved away from the functional roller 3 to be cleaned.

[0148] For the calculation of the control signals for the cleaning device motor, it is provided that a dead time between the movement of the cutting device 22 and the movement of the cleaning device 14 is taken into account, in particular calculated. The dead time can be calculated by determining the duration that a specific point on the film web 2 requires to be transported from the cutting device 22 to the cleaning device 14. An example of the consideration of the dead time is shown in Fig.9 is designated as step 152, so that a dead time is provided between the movement of the cutting device 22 and the movement of the cleaning device 14, so that the cleaning device 14 follows the movement of the cutting device 22 with a time delay corresponding to the dead time.

[0149] The invention is not limited to the illustrated and described embodiments, but also encompasses all embodiments that have the same effect within the meaning of the invention. The embodiments are not limited to the combination of all features; rather, each individual partial feature can also have inventive relevance independently of all other partial features. Furthermore, the invention is not limited to the combination of features defined in the independent claims, but can also be defined by any other combination of specific features of all disclosed individual features. Consequently, each individual feature of the respective independent claims can be omitted and / or replaced by at least one individual feature disclosed elsewhere in the application. Reference symbol list 1 Longitudinal stretching device 2 foil strips 3 Functional roller to be cleaned 4 heating rollers 6 Stretching roller 8 Cooling or annealing roller 10 Pressure roller 12 Transport roller 14 Cleaning device 16 Contact block 18 cleaning area 20 Surface to be cleaned 22 Cutting device 22.1 Layer cutting device acting as a cutting device 24 Transverse extension of the foil web 26 Cleaning gap 27 Direction of movement of the transport rollers 28 Swivel movement 30 Linear movement 32 Swivel movement 34 Linear motion 36 knife element 38 Folding device 40 Folding direction 42 Foil edge section 44 Movement of the cutting device 46 Longitudinal axis of the functional roller to be cleaned 48 Movement of the cleaning device 50 cleaning rail 52 cutting rail 54 sensor unit 56 Cutting process 58 Cleaning process 60 Center line of the foil web 62 First edge 64 Second Edge 100 Operating a longitudinal stretching device 102 Heating the foil web 104 stretchers of the foil roll 106 Cooling and / or tempering the film web 108 Cutting the foil web 110 Setting up the cleaning device 112 Moving the cutting device 114 Moving the cleaning device 116 Central insertion of the cutting device into the film web 118 Moving the cutting device in a first cutting direction 120 Extending the cutting device from the film web 122 Setting up and operating the cleaning device 124 Switching off the cleaning device 126 Return 128 Central insertion of the cutting device into the film web 130 Moving the cutting device to a second cutting direction 132 Extending the cutting device from the film web 134 Setting up and operating the cleaning device 136 Switching off the cleaning device 138 Inserting the cutting device into the film web 140 Detecting the cleaning gap 142 Setting up the cleaning roller 144 Follow the course of the cleaning gap 146 Switching off the cleaning roller 147 Determining the movement of the cutting device 148 Calculating control signals 150 Follow the course of the cleaning gap 152 Consider dead time 200 Device for producing a film web 202 Extrusion unit 204 Nozzle head 206 plastic melt 207 Double-layered plastic sheet 208 Calibration basket 210 Temperature control device 212 Flat laying unit 214 deduction 216 Reversing device 218 Further processing L hose axle Z Deduction direction M Machine direction R Course of the cleaning gap QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 20 2022 002 614 U1

[0003]

Claims

[1] Device (200) for producing a plastic film web (2), in particular a blown film line, comprising an extrusion device (202), a die head (204) for ejecting a plastic melt (206) from an outlet, a take-up (214) for drawing off the plastic melt (206) and the resulting film web (2) in a take-up direction (Z), further comprising a longitudinal stretching device (1) for monoaxially stretching the film web (2) in a machine direction (M) with a roller arrangement comprising at least two functional rollers, over which the film web (2) can be conveyed in the machine direction (M), wherein at least two functional rollers are designed as stretching rollers (6) and can be driven at different circumferential speeds for stretching the film web (2), wherein the longitudinal stretching device (1) comprises at least one cleaning device (14),which is designed to be positioned against and detachable from at least one of the functional rollers for cleaning the respective functional roller (3), characterized by at least one cutting device (22) which, viewed in the machine direction (M), is formed in front of the cleaning device (14) and can be inserted into and removed from the film web (2) perpendicular to a transverse extension (24) of the film web (2), so that the film web (2) can be cut in the longitudinal direction in such a way that a cleaning gap (26) which can be penetrated by the cleaning device (14) can be formed in the film web (2). [2] Device (200) according to claim 1, characterized by, that the roller arrangement of the longitudinal stretching device (1) also includes at least one functional roller designed as a guide roller (10, 12) for guiding and / or pressing the film web (2) and / or at least one functional roller designed as a heating roller (4) for heating the film web (2) and / or at least one functional roller designed as a cooling roller (8) for cooling the film web (2) and / or at least one functional roller designed as an annealing roller (8) for tempering the film web (2). [3] Device (200) according to claim 1 or 2, characterized by , that the cutting device (22) is arranged in front of or inside the trigger (214) when viewed in the machine direction (M). [4] Device (200) according to claim 1 or 2, characterized by , that the cutting device (22) is arranged following the machine direction (M) in an area between the take-off device (214) and the longitudinal stretching device (1). [5] Device (200) according to claim 1 or 2, characterized by, that the longitudinal stretching device (1) comprises the cutting device (22), wherein the cutting device (22) is arranged in the machine direction (M) in particular in front of the first functional roller or preferably directly in front of the functional roller (3) to be cleaned, so that the cutting device (22) is arranged in an area between the functional roller (3) to be cleaned and the respective functional roller located in front of the functional roller (3) to be cleaned when viewed in the machine direction (M). [6] Device (200) according to claim 5, characterized by , that the cleaning device (14) and the cutting device (22) are arranged directly adjacent to each other in the machine direction (M) on a common bearing unit and / or are designed as a common cutting and cleaning device. [7] Device (200) according to any of the preceding claims, characterized by, that the cutting device (22) has at least one knife element (36) for slitting the film web (2), wherein, viewed in the machine direction (M), a slitting device is arranged behind the at least one knife element (36) and is designed in such a way that the cut edges of the film web (2) resulting from the slitting can be widened in directions parallel to the transverse extension (24) of the film web (2) in directions that repel each other. [8] Device (200) according to claim 7, characterized by , that the splitting device and the cutting device (22) and / or the cleaning device (14) are arranged directly adjacent to each other in the machine direction (M) on a common bearing unit and / or are designed as a common splitting and cutting and / or cleaning device. [9] Device (200) according to claim 7 or 8, characterized by, that the slitting device is arranged and designed as a folding device (38) such that the cut edges of the film web (2) formed when the film web is cut can be folded parallel to the transverse extension (24) of the film web (2) into mutually repelling folding directions (40), so that the cleaning slit (26) is limited with double-layered film web edge sections (42), in particular that the folding device (38) has at least one pressure roller, wherein the double-layered film web edge sections (42) can be fixed by the pressure roller by means of a pressure on a folding edge formed during folding. [10] Device (200) according to any one of claims 1 to 8, characterized by, that the cutting device (22) has at least two knife elements arranged parallel to each other for cutting the film web (2) and a discharge device, in particular a suction device, wherein the discharge device is arranged behind the two knife elements when viewed in the machine direction (M) and is designed such that a strip of film cut out of the film web (2) by the knife elements longitudinally to the machine direction (M) can be discharged from the film web (2) and the cleaning gap (26) can be formed by a strip-shaped gap remaining in the film web (2). [11] Device (200) according to any of the preceding claims, characterized by, that the cleaning device (14) has a threading aid tapering towards the machine direction (M), in particular a threading aid designed as a gap device, wherein the threading aid is designed such that the cleaning device (14) can be threaded into the cleaning gap (26) when positioned against the functional roller (3) to be cleaned and the film web (2) can be guided around the cleaning device (14). [12] Device (200) according to any of the preceding claims, characterized by , that the cutting device (22) is movable parallel to the transverse extension (24) of the film web (2) and the cleaning device (14) is movable parallel to a longitudinal axis (46) of the functional roller (3) to be cleaned. [13] Device (200) according to any of the preceding claims, characterized bythat the cleaning device (14) has at least one electric cleaning device motor and can be attached to and detached from the functional roller (3) to be cleaned by means of the at least one electric cleaning device motor and can be moved parallel to the longitudinal axis (46) of the functional roller (3) to be cleaned, preferably that the cutting device (22) has at least one cutting device motor and can be moved in and out of the film web (2) by means of the at least one electric cutting device motor and can be moved parallel to the transverse extent (24) of the film web (2), wherein at least one cleaning device motor and in particular at least one cutting device motor is connected to and controllable by a control unit. [14] Device (200) according to claim 13, characterized by, that a sensor unit (54), in particular a sensor unit (54) of the longitudinal stretching device (1), is configured and connected to the control unit to detect a position of the cleaning gap (26) in the film web (2) in a section seen in the machine direction (M) in front of the functional roller (3) to be cleaned, and the control unit is configured to control the cleaning device motor depending on the position of the cleaning gap (26) in the film web (2). [15] Device (200) according to any of the preceding claims, characterized by that each of the functional rollers (3) to be cleaned has its own cleaning device (14). [16] Device (200) according to any one of claims 1 to 14, characterized by, that the cleaning device (14) is mounted on a motor-controlled, in particular electromotor-controlled, positioning frame in such a way as to be movable relative to the functional rollers in two or more cleaning positions, such that the cleaning device (14) is arranged in each cleaning position to clean a different functional roller. [17] Longitudinal stretching device (1) for monoaxial stretching of a plastic film web (2) in the machine direction (M), in particular for use in a device (200) for producing a film web (2) according to one of the preceding claims, comprising a roller arrangement having at least two functional rollers, over which the film web (2) can be conveyed in the machine direction (M), wherein at least two functional rollers are designed as stretching rollers (6) and can be driven at different circumferential speeds for stretching the film web (2), further comprising at least one cleaning device (14) which is designed to be attachable to and detachable from the respective functional roller (3) for cleaning at least one of the functional rollers, characterized by, that the cleaning device (14) is designed such that a cleaning gap (26) extending in the longitudinal direction of the film web can be penetrated by means of the cleaning device (14), in particular a cleaning gap (26) cut in the longitudinal direction into the film web (2) by means of the cutting device (22). [18] Longitudinal stretching device (1) according to claim 17, characterized by, that the longitudinal stretching device (1) comprises the cutting device (22), wherein the cutting device (22) is designed to be retractable into and out of the film web (2) in the machine direction (M) in front of the functional roller (3) to be cleaned and perpendicular to a transverse extension (24) of the film web (2), so that the film web (2) can be cut in the longitudinal direction in such a way that the cleaning gap (26) through which the cleaning device (14) can be formed in the film web (2), in particular that the cutting device (22) is arranged in front of the first functional roller of the roller arrangement or preferably is arranged directly in front of the functional roller (3) to be cleaned, so that the cutting device (22) is arranged in an area between the functional roller (3) to be cleaned and the functional roller arranged in the machine direction (M) in front of the functional roller (3) to be cleaned. [19] Longitudinal stretching device (1) according to claim 16 or 17, characterized by, the features relating to the longitudinal stretching device (1) of any one of claims 1 to 16. [20] Method for cleaning (100) at least one functional roller (3) of a longitudinal stretching device (1), in particular a longitudinal stretching device (1) according to one of claims 17 to 19, preferably a device (200) for producing a film web (2) made of plastic according to one of claims 1 to 16, wherein the film web (2) made of plastic is conveyed through the longitudinal stretching device (1) by means of a roller arrangement with at least two functional rollers, at least two of which are designed as stretching rollers (6), characterized by, that at least one of the functional rollers (3) is cleaned by means of a cleaning device (14) by cutting the film web (2) longitudinally (108) by means of a cutting device (22) arranged in front of the cleaning device (14) in the machine direction (M), which can be inserted into and removed from the film web (2), so that a cleaning gap (26) is formed, through which the cleaning device (14) positions itself against the functional roller (3) to be cleaned (110). [21] Method (100) according to claim 20, characterized by, that while the cutting device (22) is inserted into the film web (2) and is cutting the film web (2), the cutting device (22) moves parallel to a transverse extension (24) of the film web (2) (112), wherein the cleaning gap (26) is continuously cut into the film web (2) following the cutting device (22), wherein the cleaning device (14), while it is positioned against the functional roller (3) to be cleaned, follows the movement of the cutting device (22) and the course of the cleaning gap parallel to a longitudinal axis (46) of the functional roller (3) to be cleaned in such a way that the cleaning device (14) is always in engagement with the respective functional roller to be cleaned and is arranged within the cleaning gap (26) (114). [22] Method (100) according to claim 21, characterized by, that, for cleaning the respective functional roller, the cutting device (22) enters the film web (2) centrally to the transverse extent (24) of the film web (2) (116) and moves in a first cutting direction (S1) parallel to a transverse extent (24) of the film web (2) along a first cutting path, in particular at least up to a first edge (62) of the maximum transverse extent (24) of the film web (2) (118) and subsequently exits the film web (2) (120), wherein the cleaning device (14) correspondingly, with a delay, first engages the cleaning gap (26) formed centrally in the film web (2) by the cutting device (22) and positions itself against the functional roller (3) to be cleaned and moves in the same direction as the first cutting direction (S1) of the movement of the cutting device (22) and the course of the cleaning gap, in particular up to a first axial end of a surface (20) to be cleaned. cleaning functional roller (3),follows (122) and subsequently extends from the cleaning gap (26) and / or moves away from the functional roller (3) to be cleaned (124). [23] Method (100) according to claim 22, characterized by, that for cleaning the respective functional roller the cutting device (22) enters the film web (2) centrally to the transverse extent (24) of the film web (2) (128) and points to a second cutting direction (S2) parallel to the transverse extent (24) of the film web (2) along a second cutting path and opposite to the first cutting direction (S1), in particular at least up to a second edge (64) of the maximum transverse extent (24) of the film web (2) formed opposite the first edge (62) of the maximum transverse extent (24) of the film web (2) (130) and subsequently exits the film web (2) (132),wherein the cleaning device (14) correspondingly, with a delay, first penetrates the cleaning gap (26) formed centrally in the film web (2) by the cutting device (22) and positions itself against the functional roller (3) to be cleaned and follows the movement of the cutting device (22) and the course (R) of the cleaning gap (26) in the same direction as the second cutting direction (S2), in particular up to a second axial end of the surface (20) to be cleaned of the functional roller (3) to be cleaned, opposite the first axial end of the surface (20) to be cleaned (134) and subsequently extends out of the cleaning gap (26) and / or moves away from the functional roller (3) to be cleaned (136). [24] Method (100) according to any one of claims 20 to 23, characterized by, that the cleaning device (14) is positioned against the functional roller (3) to be cleaned by means of at least one electric cleaning device motor and is positioned away from the functional roller (3) to be cleaned and is moved parallel to the longitudinal axis (46) of the functional roller (3) to be cleaned, preferably that the cutting device (22) is inserted into the film web (2) and removed from the film web (2) by means of at least one electric cutting device motor and / or is moved parallel to the transverse extent (24) of the film web (2), wherein at least one electric cleaning device motor, and in particular also at least one electric cutting device motor, is controlled by means of a control unit. [25] Method (100) according to claim 24, characterized by, that a position of the cleaning gap (26) in the film web (2) in a section seen in the machine direction (M) in front of the functional roller (3) to be cleaned is detected by means of a sensor unit connected to the control unit (140) and depending on the position of the cleaning gap (26) in the film web (2) the cleaning device motor is controlled in such a way that the cleaning device (14) at least follows the position or course (R) of the cleaning gap (26) on the film web (2) (144). [26] Method (100) according to claim 25, characterized by , that when a cleaning gap (26) is detected, the cleaning device (14) moves through the cleaning gap (26) towards the functional roller (3) to be cleaned (142) and when an end of the cleaning gap (26) is detected, moves away from the functional roller (3) to be cleaned (146). [27] Method (100) according to any one of claims 21 to 26, characterized by, that the movement of the cleaning device (14) is synchronized with the movement of the cutting device (22) such that the movement of the cleaning device (14) is calculated as a function of the movement of the cutting device (22) (148), in particular that the movement of the cleaning device (14) corresponds to the movement of the cutting device (22), taking into account a dead time between the movements (152), which is calculated from a film travel time that a certain point on the film web (2) requires to be transported from the cutting device (22) to the cleaning device (14). [28] Cleaning device (14) for retrofitting in a longitudinal corner device (1) and / or a device (200) for producing a film web (2) made of plastic, wherein the cleaning device (14) has the features of the cleaning device (14) of at least one of claims 1 to 19, in particular that the cleaning device (14) comprises a cutting device (22) and is formed together with the cutting device (22) on a common bearing unit, in particular that the cutting device (22) and the cleaning device (14) are designed as a common cutting and cleaning device and / or preferably comprise a slitting device.

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