Longitudinal stretching machine with cleaning device

Abstract

The invention relates to a longitudinal stretching machine (1) for stretching a film web (2), comprising guide rollers for guiding and / or pressing the film web (2), at least one heating roller (4) for heating the film web (2), at least two stretching rollers (6) for stretching the film web (2) in a machine direction (M) and at least one cooling roller (8) for cooling the film web (2) and / or an annealing roller (8) for controlling the temperature of the film web (2). Furthermore, the machine has at least one cleaning device (14), which is designed in such a way for cleaning one of the guide rollers or the at least one heating roller (4) or one of the stretching rollers (6) or the at least one cooling roller (8) or annealing roller (8) that it can be placed against and removed from the respective roller. The invention furthermore relates to a method and to a film extrusion system.

Description

[0001] Windmöller & Hölscher KG

[0002] Münsterstraße 50

[0003] 49525 Lengerich / Westphalia

[0004] Our reference number: 9529WO

[0005] Longitudinal stretching machine with cleaning device

[0006] The invention relates to a longitudinal stretching machine. With this machine, a film web can be stretched in one machine direction. The longitudinal stretching machine has guide rollers for guiding the film web and / or for pressing the film web against other rollers. Furthermore, the longitudinal stretching machine has at least one heating roller for heating the film web and at least two stretching rollers for stretching the film web in the machine direction. It is provided that the longitudinal stretching machine includes at least one cooling roller for cooling the film web and, alternatively or additionally, an annealing roller for tempering the film web. A cleaning device is also provided, which is designed to be attached to and detached from the respective roller for cleaning one of the guide rollers, the heating roller, the stretching rollers, the cooling roller, or the annealing roller.

[0007] Such a longitudinal stretching machine is known, for example, from DE 20 2022 002 614 U1.

[0008] Such a longitudinal stretching machine can be directly integrated as a station within a film extrusion line, whether a blown film line or a cast film line. Alternatively, the longitudinal stretching machine can be operated as a separate, "offline" unit from the film extrusion line for the post-processing of the extruded film. The longitudinal stretching machine, also known as an MDO (machine direction orientation) stretching unit, typically consists of numerous temperature-controlled chrome rollers and / or vacuum-operated porous rollers that rotate or are driven at different speeds and are arranged very close together to minimize the free film length of the film web being stretched between the individual rollers.By means of guide rollers designed as pressure rollers, or other means, the film web is held on the stretching rollers, which are preferably made of chrome and / or, in particular, are porous and can be pressurized with a vacuum, and stretched in the machine direction or longitudinally, whereby the crystals in the film web align themselves in the tension direction 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 rollers will not be discussed in detail.

[0009] The appearance of a film, particularly its transparency, is influenced by many parameters during MDO treatment. Contamination of the 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 roller(s) and to unthread or detach the film web from the respective roller(s) so that the respective roller(s) can be cleaned in the longitudinal stretching machine, in particular by means of a cleaning device such as that known from DE 20 2022 002 614 U1.It is also known to reduce the MDO treatment so that the respective roller(s) are accessible for disassembly and subsequent cleaning outside the longitudinal stretching machine. Disassembly of the 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.

[0010] 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 the rollers, preferably without interrupting production and / or having to unwind and rewind the film web.

[0011] 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.

[0012] According to the invention, a cutting device is provided in front of the roller to be cleaned, viewed in the machine direction. This cutting device is designed to be retractable into and out of the film web perpendicular to a transverse dimension of the film web, such that the film web can be cut longitudinally in such a way that a cleaning gap is formed in the film web which can be penetrated by the cleaning device.

[0013] Because the cleaning device can engage the film web through the cleaning gap, it is possible to attach the cleaning device to the roller to be cleaned during ongoing production. In contrast to known cleaning devices, the embodiment according to the invention therefore does not require interrupting production and removing and re-threading the film web for cleaning. Disassembly and assembly, as is particularly common with manual cleaning of the respective rollers, are eliminated, as are the cooling and heating phases required for this process. An advantageous embodiment of the invention is achieved by the cutting device comprising a blade element for cutting the film web and a folding mechanism.Advantageously, the folding device is arranged behind the knife element when viewed in the machine direction and is designed in such a way that the cut edges created when cutting are folded in directions that repel each other parallel to the transverse extension of the film web.

[0014] An advantage of this design variant is that the cleaning gap is limited by double-layered film edge sections. These double-layered film edge sections prevent tearing of the film web when the cleaning gap is created, especially compared to simply spreading the film edge sections without folding them over, which would result in creases forming in the film edge sections. Furthermore, the folding allows the film edge sections to be transported in such a way that the individual film layers of the double-layered film edge sections lie flat on top of each other as they are transported over the respective rollers of the longitudinal stretching machine. This also prevents tearing and / or uncontrolled behavior of the film web during its passage through the longitudinal stretching machine.

[0015] 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 roller being cleaned. Moving the cleaning device parallel to the longitudinal axis of the roller allows it to clean the roller over a larger axial range. Because the cutting device also moves parallel to a transverse axis of the film web, the cleaning gap created by the cutting device can move with the position of the cleaning device, ensuring that the cleaning device always maintains full contact with the roller being cleaned and can effectively clean the roller.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 roller to be cleaned and moved parallel to the longitudinal axis of the roller. Since the longitudinal stretching machine 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 particularly advantageous. Furthermore, the electric cleaning device motor allows the required installation space of the longitudinal stretching machine with its motor-driven cleaning device to be kept to a minimum.

[0016] 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 of the longitudinal stretching machine can be kept small and process reliability can be increased.

[0017] Preferably, at least one cleaning device motor is connected to a control unit and can be controlled by means of this control unit. Preferably, the at least one cutting device motor is also connected to the control unit and can be controlled by means of the control unit. The control unit can be designed as a remote control operable 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. 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 or retraction of the cutting device into or out of the film web and / or the movement of the cleaning device axially to the roller to be cleaned and / or the starting or stopping of the cleaning device can be controlled by the control unit.Positioning the cleaning device against the roller to be cleaned is carried out manually and / or by means of at least one cleaning device motor or at least one cutting device motor. The respective motors can be controlled by the control unit either manually via remote control or by a control program running in the control unit.

[0018] 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 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 roller to be cleaned to the switched-off position and out of the cleaning gap.

[0019] 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.

[0020] Particularly for the automation of the cleaning process, a special embodiment of the longitudinal stretching machine provides that the machine has a sensor unit. This sensor unit is advantageously connected 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 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. In this embodiment, it is advantageously provided that the cleaning device is designed to follow the path of the cleaning gap, or to move into the respective 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 move out of the respective cleaning gap.

[0021] An advantageous embodiment of the invention provides that the cutting device is arranged, viewed in the machine direction, upstream of the at least one heating roller and / or the stretching rollers and / or the at least one cooling roller and / or the at least one annealing roller. In particular, it is essential that the cutting device is arranged, viewed in the machine direction, at least upstream of the respective roller to be cleaned. A particular embodiment provides that the cutting device is arranged upstream of all heating, stretching, cooling, and annealing rollers of the longitudinal stretching machine. Particularly preferred is the cutting device also arranged upstream of the first guide roller of the longitudinal stretching machine, so that, especially when the longitudinal stretching machine is integrated into the film extrusion line, the film web is first guided over the cutting device into the longitudinal stretching machine or to the respective rollers of the longitudinal stretching machine.Alternatively, a particular embodiment of the invention provides that the cutting device, viewed in the machine direction, is arranged between two guide rollers designed as transport rollers. In practice, it has been shown that the operating time of the respective longitudinal stretching machine can be improved by ensuring that at least one of the stretching rollers can be cleaned by the cleaning device of the aforementioned type.

[0022] The problem underlying the invention is further solved by a method for operating the longitudinal stretching machine. In particular, the method integrates a cleaning process for cleaning one of the rollers of the longitudinal stretching machine into an MDO process in such a way that the ongoing production does not have to be interrupted for cleaning the roller to be cleaned. Advantageously, the method relates to the operation of one of the aforementioned embodiments of the longitudinal stretching machine. Preferably, a longitudinal stretching machine that is integrated into a film extrusion line.

[0023] The process involves first heating the film web using at least one heating roller, then stretching it in one machine direction using at least two stretching rollers, and subsequently cooling it using at least one cooling roller and / or tempering it using at least one annealing roller. During the process, the film web is guided by guide rollers, which advantageously allow the film web to be guided, deflected, and / or pressed against the other rollers.

[0024] According to the invention, the method provides that at least one of the rollers of the longitudinal stretching machine is cleaned by cutting the film web longitudinally by means of the cutting device arranged in the machine direction in front of the roller to be cleaned, which can be inserted into and withdrawn from the film web, so that a cleaning gap is created through which the cleaning device is positioned against the roller to be cleaned.

[0025] The roller to be cleaned can be one of the guide rollers and / or at least one heating roller and / or one of the stretching rollers and / or at least one cooling roller or at least one annealing roller. If the process involves cleaning two or more rollers, a separate cleaning device must be provided for each roller. Furthermore, if there are two or more rollers to be cleaned, at least one cutting device must be arranged upstream of each roller in the direction of machine cleaning.

[0026] 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 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 roller. For cleaning the respective roller, it is highly advantageous if the cleaning device remains positioned against the roller and within the cleaning gap while following its path.

[0027] A further advantageous embodiment of the method is based on the fact that, for cleaning the respective roller, the cutting device is inserted into the film web centrally to its transverse extent. After the cutting device has been inserted into the film web, it moves in a first cutting direction parallel to a transverse extent of the film web, in particular at least to a first edge of the maximum transverse extent of the film web. Subsequently, the cutting device moves out of the film web again. 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.It is advantageous for the cleaning device to initially move through the cleaning gap formed by the cutting device in the center of the film web and align itself with the roller to be cleaned, corresponding to the cutting device. Advantageously, the cutting device then follows the movement of the cutting device and the path 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 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.

[0028] Preferably, the cleaning device is designed to disengage from the 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 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 roller to be cleaned.

[0029] According to further advantageous process steps, the cutting device then enters the film web centrally to its transverse extent for cleaning the respective roller and moves in a second cutting direction parallel to a transverse extent of the film web, in particular at least to a second edge of the maximum 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 achieved by lifting it out of the film web or by moving in the second cutting direction beyond the second edge of the maximum transverse extent of the film web.In particular, it can be provided that the cleaning device initially engages the cleaning gap formed by the cutting device in the center of the film web with a time delay corresponding to the cutting device, and then positions itself against the 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 roller to be cleaned.

[0030] Advantageously, the cleaning device moves out of the cleaning gap and / or moves away from the roller to be cleaned after it has moved a predetermined distance in the second cutting direction in the manner described above.

[0031] 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 roller to be cleaned.

[0032] 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 roller to be cleaned by means of at least one electric cleaning device motor and is moved parallel to the longitudinal axis of the 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 machine, 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.

[0033] 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 roller to be cleaned, 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.

[0034] 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 roller to be cleaned, and upon detecting the end of the cleaning gap, it moves away from the 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.

[0035] 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.

[0036] Furthermore, the problem underlying the invention is solved by a film extrusion plant for producing a film with a longitudinal stretching machine for stretching the film web in the machine direction, wherein the longitudinal stretching machine has the features of at least one of the aforementioned embodiments. Advantageously, it can also be provided that the film extrusion plant is designed such that the inventive method for operating the longitudinal stretching machine or an advantageous variant of this method can be carried out on the film extrusion plant.

[0037] 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 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 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.

[0038] The individual figures show: Fig. 1 a schematic side view of a longitudinal stretching machine for stretching a film web,

[0039] Fig. 2z is a schematic representation in viewing direction A according to Fig. 1 of the longitudinal stretching machine. Fig. 1 ,

[0040] Fig. 3 shows a schematic sectional view along a transverse extension of the film web in the area B according to Fig. 1 of a cleaning device positioned on the roller to be cleaned, passing through a cleaning gap of the film web.

[0041] Fig. 4 shows a schematic representation of the path of a cutting device and a cleaning device relative to the film web,

[0042] Fig. 5 shows a schematic representation of a method for operating the longitudinal stretching machine,

[0043] Fig. 6 shows a schematic representation of another method for operating the longitudinal stretching machine.

[0044] Fig. 7 shows a schematic representation of another method for

[0045] Operating the longitudinal stretching machine and

[0046] Fig. 8 shows a schematic representation of another method for

[0047] Operating the longitudinal stretching machine.

[0048] In the various figures of the drawing, identical parts are always provided with the same reference numerals. For the purposes of 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, both independently of all other partial features described in connection therewith and also in combination with any features of another exemplary embodiment.

[0049] Fig. 1 shows a longitudinal stretching machine 1, as it can be integrated, in particular, into a film extrusion line (not shown). The longitudinal stretching machine 1 can stretch a film web 2 in a machine direction M.

[0050] The longitudinal stretching machine 1 has guide rollers, at least one heating roller 4 for heating the film web 2, at least two stretching rollers 6 for stretching the film web 2 in the machine direction M, and at least one cooling roller 8 for cooling the film web 2 and / or an annealing roller 8 for tempering the film web 2. For illustrative purposes, Fig. 1 shows only one heating roller 4, which is arranged in the machine direction M upstream of the two stretching rollers 6 shown, and only one cooling or annealing roller 8, which is arranged downstream of the stretching rollers 6 in the machine direction M. However, the number of each type of roller can exceed the configuration shown in Fig. 1. To clarify this, the film web 2 in Fig. 1 is shown with dashed lines after the heating roller 4, after the last stretching roller 6 in the machine direction M, and after the cooling or annealing roller 8, which implies optional additional rollers between the rollers shown.

[0051] The guide rollers can be designed, in particular, as pressure rollers 10 for pressing the film web 2 against another roller, or, advantageously, as transport rollers 12, in particular for guiding and / or deflecting the film web 2. The pressure rollers are shown only in Fig. 1.

[0052] 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 of the respective stretching rollers 6 or a difference in diameter of the respective stretching rollers 6 causes longitudinal stretching of the film web 2 when the film web 2 is transported in the machine direction M.

[0053] It is further provided that the longitudinal stretching machine 1 has at least one cleaning device 14, which is designed to be attached to and detached from one of the guide rollers, or the at least one heating roller 4, or one of the stretching rollers 6, or the at least one cooling roller 8, or annealing roller 8, for cleaning this roller. Figures 1 to 3 show an advantageous embodiment in which the longitudinal stretching machine 1 has only one cleaning device 14 for cleaning one roller, wherein the roller 3 to be cleaned is one of the stretching rollers 6. It is within the scope of the invention that further and / or other rollers can also be cleaned by means of a cleaning device 14.

[0054] Since the roller 3 to be cleaned is driven or can be driven by rotation during operation of the longitudinal stretching machine 1, particularly via a corresponding roller drive, a special embodiment provides that the cleaning device 14 includes a contact block 16, as shown by way of example in Fig. 3. The contact block 16 has a cleaning surface 18 which, at least in the position facing the roller 3 to be cleaned, is oriented towards it. In this position, the contact block 16 with the cleaning surface 18 rubs against a surface 20 of the roller 3 to be cleaned, thus effecting contact cleaning. Since the roller cleaning can be carried out during operation of the longitudinal stretching machine 1 and the respective roller is driven by 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.

[0055] Figures 1 and 2 show that, according to the invention, a cutting device 22 is provided in front of the roller 3 to be cleaned, viewed in the machine direction M. The cutting device 22 is designed such that, as shown particularly in Figure 2, it can be inserted into and withdrawn from the film web 2 perpendicular to a transverse dimension 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, is formed. Figures 2 and 3 show in particular how the cleaning device 14 is positioned against the roller 3 to be cleaned, in particular the stretching roller 6, and thereby penetrates the cleaning gap 26.

[0056] Advantageously, the cutting device 22 for providing the cleaning gap 26, as shown in Figures 1 and 2, is positioned in the machine direction M upstream 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. Furthermore, the cutting device 22 can be arranged between two guide rollers designed as transport rollers 12 with respect to the machine direction M. The guide rollers designed as transport rollers 12 ensure reliable guidance of the film web 2, so that the cutting device 22 can reliably enter and exit the film web 2. In particular, the cutting behavior of the film web 2 can be optimized.The behavior of the film web 2 during the insertion and retraction of the cutting device 22 can be influenced and adapted to the specific application by varying the distance between the two guide rollers, designed as transport rollers 12, between which the cutting device 22 is arranged. For example, the guide rollers designed as transport rollers 12 can be arranged to be radially displaceable about their respective longitudinal axes, see arrows 27 in Fig. 1.

[0057] In an alternative configuration not shown, the cutting device 22 can also be arranged in front of the guide rollers when viewed in the machine direction M. This configuration can be advantageous if the film web 2 is already fed to the longitudinal stretching machine 1 in a suitable manner.

[0058] The elements of the cutting device 22 that are not visible in Fig. 2, or the elements of the cutting device 22 that are hidden or covered by the film web 2 during the operation of the longitudinal stretching machine 1, are marked with dashed lines for better understanding.

[0059] In practice, it has proven advantageous if the cutting device 22 is designed to pivot about a rotational axis for insertion into and removal from 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, both the pivoting movement 28 and the linear movement 30 are shown in Fig. 1. In particular, it can be provided that the cutting device 22 has at least one cutting device motor, preferably an electric motor, for insertion into and removal from the film web 2.

[0060] Similarly, the cleaning device 14 can be designed such that it is pivotable about a rotary axis 32 for positioning itself against and detaching from the roller 3 to be cleaned, and / or can move along a linear travel path 34 for positioning itself against and detaching from the roller 3 to be cleaned. The two alternative or complementary variants are shown in Fig. 1. In particular, the cleaning device 14 can be provided with at least one, preferably electric, cleaning device motor for positioning itself against and detaching from the roller 3 to be cleaned.

[0061] As shown in Figures 1 and 2, an advantageous embodiment of the cutting device 22 comprises a knife element 36 for cutting the film web 2 and a folding device 38. It is particularly advantageous if the folding device 38 is designed such that the cut edges resulting from the cutting process are folded parallel to the transverse dimension 24 of the film web 2 in directions 40 that repel each other. Figure 2 shows by way of example that, viewed in the machine direction M, the folding device 38 is expediently arranged behind the knife element 36 and folds the cut edges. A particular advantage is that the folding process creates the double-layered film web edge sections 42 shown in Figures 2 to 4, which advantageously limit the cleaning gap 26.

[0062] In particular, it is provided that the cutting device 22 is parallel to the

[0063] The cutting device 22 and the cleaning device 14 are movable along the transverse axis 24 of the film web 2 (see arrows L in Fig. 2), and the cleaning device 14 is movable parallel to a longitudinal axis 46 of the roller 3 to be cleaned (see arrows 48 in Fig. 2). Advantageously, the cutting device 22 and the cleaning device 14 are each mounted in a guide rail 50, 52, in which they are preferably motor-driven to provide these respective movements. In particular, the cleaning device 14 is mounted in a cleaning rail 50 and can be moved manually and / or by motor. Alternatively or additionally, the cutting device is mounted in a cutting rail 52 and can be moved manually and / or by motor. The cutting rail 52 and the cleaning rail 50 are shown by way of example in Fig. 2.

[0064] 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 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.

[0065] 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

[0066] The cutting 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 not shown in Figures 1 to 4. According to an advantageous embodiment of the invention, the longitudinal stretching machine 1 and / or the control unit has 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 roller 3 to be cleaned. Figure 1 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 detects an area in front of the roller 3 to be cleaned.The control unit monitors the position of the cleaning gap 26 in the film web 2. In combination with the sensor unit 54, the control unit is preferably designed 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 cleaning device 14 to follow the path of the cleaning gap 26 if it shifts, especially relative to the transverse extent 24 of the film web 2, as shown in Fig. 4, regardless of whether the movement of the cutting device 22 is controlled and / or monitored manually or automatically.

[0067] To operate 100 the longitudinal stretching machine 1, in particular the one according to the invention or an optional variant of the aforementioned type, it is now provided that the film web 2 is first heated by means of the at least one heating roller 4, see step 102 in Fig. 5.

[0068] The film web 2 is then stretched in the machine direction M by means of at least two stretching rollers 6, see step 104 in Fig. 5.

[0069] Subsequently, the film web 2 is 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. 5.

[0070] While the longitudinal stretching machine 1 is operating, the film web 2 is guided by means of the guide rollers. According to the invention, at least the respective roller 3 to be cleaned 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 in such a way that the cutting device 22 moves into the film web 2, so that the cleaning gap 26 is formed, see step 108 in Fig. 5.

[0071] Furthermore, process step 110 provides that the cleaning device 14, particularly in the manner described above, is positioned so that the cleaning gap 26 extends through the cleaning gap 26 to the roller 3 to be cleaned. In Fig. 5, corresponding to the embodiment of the longitudinal stretching machine 1 shown in Fig. 1, 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 roller 3 to be cleaned in a suitable manner by the cutting device 22, so that a sequence of processes deviating from the one shown in Fig. 5 is also within the scope of the invention.

[0072] Optionally, method 100 can be supplemented, in particular, by moving the cutting device 22 parallel to the transverse dimension 24 of the film web 2 while it is inserted into and cutting the film web 2, see step 112 in Fig. 5. 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. 4 schematically shows an advantageous cutting path 56 as it extends longitudinally through the film web 2 when the cutting device 22 is moved in a transverse dimension 24 of the film web 2 during transport of the film web 2 in the machine direction M.For particularly advantageous cleaning of the roller 3 to be cleaned, an advantageous process step 114 provides that the cleaning device 14, while it is positioned against the roller 3 to be cleaned, follows the movement of the cutting device 22 and the course R of the cleaning gap 26 parallel to the longitudinal axis 46 of the roller 3 to be cleaned in such a way that the cleaning device 14 is always in engagement with the respective roller and, as shown in Fig. 3, is arranged within the cleaning gap 26.

[0073] Since steps 108 to 114 can be carried out essentially in parallel with steps 102 to 106, or since it is not necessary to shut down production to carry out steps 108 to 114, steps 102 to 106 are shown in Fig. 5 in parallel with steps 108 to 114.

[0074] Referring to the schematic representation in Fig. 4, this means that 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, is 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.

[0075] In the advantageous embodiment according to Fig. 4, it is expediently provided that in a step 116, see Fig. 6, the cutting device 22 first enters the film web 2 centrally to its transverse extent 24 and in a step 118 moves in a first cutting direction S1 parallel to a transverse extent 24 of the film web 2. In Fig. 4, a center line 60 of the film web 2 is shown by way of example. Expediently, the cutting device 22 moves up to a first edge 62 of the maximum transverse extent 24 of the film web 2, particularly as shown in Fig. 4.

[0076] Subsequently, the cutting device 22, see step 120 in Fig. 6, moves out of the film web 2. This can be achieved 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. 4, and / or by positioning 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.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, engages the cleaning gap 26 created by the cutting device 22 in the center of the film web 2 and positions itself against the roller 3 to be cleaned, see step 122 in Fig. 6. 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. 6, moves out of the cleaning gap 26, see Fig. 4, and / or moves away from the roller 3 to be cleaned.

[0077] 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 roller 3 to be cleaned.

[0078] To ensure complete cleaning of the roller 3 to be cleaned, a second cutting and cleaning of the roller 3 to be cleaned is regularly advantageous.

[0079] In particular, in this case, the aforementioned method 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. 6. For this purpose, the cleaning device 14 and the cutting device 22 are first spaced perpendicular to the machine direction M from the film web 2 such that between the surface plane of the film web facing the cleaning device 14 and the cutting device 22 respectively, there is a distance between the two surfaces of the film web.

[0080] A gap is formed between the cutting device 2 and the cutting device 22. The cutting device 22 can then be positioned parallel to the transverse axis 24 and the cleaning device 14 parallel to the longitudinal axis 46 of the roller to be cleaned.

[0081] 3 are moved into a substantially central position relative to the transverse extent 24 of the film web 2. 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 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. 6, and then moves out of the film web 2, see step 132 in Fig. 6. The second edge 64 of the maximum transverse extent 24 of the film web 2 is in particular arranged opposite the first edge 62 of the maximum transverse extent 24 of the film web 2, as shown in Fig. 4.In particular, it is provided that the process steps 128 to 132 correspond in their sequence and execution possibilities 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.

[0082] 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 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 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 of the roller 3 to be cleaned, 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 Fig. 4.

[0083] Figure 4 illustrates the aforementioned process steps 116 to 136 using an exemplary film web 2. Process steps 116 to 136 create two cleaning slits 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 slits 26 each extend from a point centrally located relative to the transverse dimension 24 of the film web 2 into the film web 2, 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 slits, can contact and clean the 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.

[0084] It is particularly within the scope of the invention that the movement of the cutting device 22 parallel to the transverse extension 24 of the film web 2 and / or the extension and retraction of the cutting device 22 into and out of the film web 2 and / or the movement of the cleaning device 14 axially to the roller 3 to be cleaned and / or the connection and disconnection of the cleaning device 14 to the 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. The respective motors are controlled by the control unit by manual input via the remote control or by a control program running in the control unit.

[0085] Figure 7 shows a further supplementary or alternative variant for carrying out method 100 for operating the longitudinal stretching machine 1. Accordingly, it is self-evident that method 100, in particular the method shown in Figures 5 and / or 6, can be carried out and / or improved using the sensor unit 54, in particular the optical detection unit 54, for detecting the position of the cleaning gap 26. This is achieved by detecting the position of the cleaning gap 26 in the film web 2 in the area in front of the roller 3 to be cleaned, as seen in the machine direction M. Depending on the position of the cleaning gap 26 and / or the beginning and / or the end of the cleaning gap 26 in the film web 2, the cleaning device motor is controlled by the control unit. This variant is shown in particular in Figure 7.It is advantageously provided 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.

[0086] The method variant shown in Fig. 7 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 in the longitudinal direction, see step 138 in Fig. 7.

[0087] The control unit advantageously detects 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 by means of the sensor unit 54, see step 140 in Fig. 7. The control unit controls the at least one cleaning device motor such 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 roller 3 to be cleaned through the cleaning gap 26, see step 142 in Fig. 7.

[0088] 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. 7.

[0089] 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 roller 3 to be cleaned before the end of the cleaning gap 26 reaches the cleaning device 14, see step 146 in Fig. 7.

[0090] An additional 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 shown by way of example in Fig. 8. For this purpose, it is advantageous that the movement of the cutting device 22, in particular the entry into and exit from the film web 2 and / or the movement parallel to the transverse extent 24 of the film web 2, can be determined or is determined, see step 147 in Fig. 8. This can advantageously be done via sensors, in particular optical detection devices, e.g. image recognition or

[0091] Laser distance measuring devices are used. 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.

[0092] As shown in Fig. 8, 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 are calculated by the control unit to move the cleaning device 14 as a function of the movement of the cutting device 22, see step 148 in Fig. 8. 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. 8. In particular, in a special variant of the method, control signals can also be calculated by the control unit based on the movement of the cutting device 22, by means of which the cleaning device 14 is positioned against and removed from the roller 3 to be cleaned.

[0093] 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, and 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. The consideration of the dead time is shown as an example in Fig. 8, marked as step 152, so that the dead time is provided between the movement of the cutting device 22 and the movement of the cleaning device 14, such that the cleaning device 14 follows the movement of the cutting device 22 with a time delay corresponding to the dead time.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.

[0094] Reference symbol list

[0095] 1 Longitudinal stretching device

[0096] 2 foil strips

[0097] 3 Roller to be cleaned

[0098] 4 heating rollers

[0099] 6 Stretching roller

[0100] 8 Cooling or annealing roller

[0101] 10 Pressure roller

[0102] 12 Transport roller

[0103] 14 Cleaning device

[0104] 16 Contact block

[0105] 18 cleaning area

[0106] 20 Surface to be cleaned

[0107] 22 Cutting device

[0108] 24 Transverse extension of the foil web

[0109] 26 Cleaning gap

[0110] 27 Direction of movement of the transport rollers

[0111] 28 Swivel movement

[0112] 30 Linear movement

[0113] 32 Swivel movement

[0114] 34 Linear motion

[0115] 36 knife element

[0116] 38 Folding device

[0117] 40 Folding direction

[0118] 42 Foil edge section

[0119] 44 Movement of the cutting device

[0120] 46 Longitudinal axis of the roller to be cleaned

[0121] 48 Movement of the cleaning device

[0122] 50 cleaning rail

[0123] 52 cutting rail

[0124] 54 sensor unit

[0125] 56 Cutting process

[0126] 58 Cleaning process

[0127] 60 Center line of the foil web 62 First edge

[0128] 64 Second Edge

[0129] 100 Operating a longitudinal stretching machine

[0130] 102 Heating the foil web

[0131] 104 stretchers of the foil roll

[0132] 106 Cooling and / or tempering the film web

[0133] 108 Cutting the foil web

[0134] 110 Setting up the cleaning device

[0135] 112 Moving the cutting device

[0136] 114 Moving the cleaning device

[0137] 116 Central insertion of the cutting device into the film web

[0138] 118 Moving the cutting device in a first cutting direction

[0139] 120 Extending the cutting device from the film web

[0140] 122 Setting up and operating the cleaning device

[0141] 124 Switching off the cleaning device

[0142] 126 Return

[0143] 128 Central insertion of the cutting device into the film web

[0144] 130 Moving the cutting device to a second cutting direction

[0145] 132 Extending the cutting device from the film web

[0146] 134 Setting up and operating the cleaning device

[0147] 136 Switching off the cleaning device

[0148] 138 Inserting the cutting device into the film web

[0149] 140 Detecting the cleaning gap

[0150] 142 Setting up the cleaning roller

[0151] 144 Follow the course of the cleaning gap

[0152] 146 Switching off the cleaning roller

[0153] 147 Determining the movement of the cutting device

[0154] 148 Calculating control signals

[0155] 150 Follow the course of the cleaning gap

[0156] 152 Consider dead time

[0157] M Machine direction

[0158] R Course of the cleaning gap

Claims

Windmöller & Hölscher KG Münsterstraße 50 49525 Lengerich / Westphalia Our reference number: 9529WO Longitudinal stretching machine with cleaning device Claims 1. Longitudinal stretching machine (1), in particular a film extrusion plant, for stretching a film web (2) in a machine direction (M), comprising guide rollers for guiding and / or pressing the film web (2), at least one heating roller (4) for heating the film web (2), at least two stretching rollers (6) for stretching the film web (2) in the machine direction (M) and at least one cooling roller (8) for cooling the film web (2) and / or an annealing roller (8) for tempering the film web (2), further comprising at least one cleaning device (14) which is designed to be attached to and detached from the respective roller for cleaning one of the guide rollers or the at least one heating roller (4) or one of the stretching rollers (6) or the at least one cooling roller (8) or annealing roller (8).characterized in that, viewed in the machine direction (M), a cutting device (22) is formed in front of the roller (3) to be cleaned, which can be inserted into and withdrawn from the film web (2) perpendicular to a transverse extension (24) of the film web (2) and by means of which 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) is formed in the film web (2).

2. Longitudinal stretching machine (1) according to claim 1, characterized in that the cutting device (22) has a knife element (36) for cutting the film web (2) and a folding device (38), wherein the folding device (38) is arranged and designed behind the knife element (36) when viewed in the machine direction (M) such that cut edges of the film web (2), which are formed during cutting, are folded parallel to the transverse extension (24) of the film web (2) in directions that repel each other, so that the cleaning gap (26) is limited with double-layered film web edge sections (42).

3. Longitudinal stretching machine (1 ) according to claim 1 or 2, characterized in 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 roller (3) to be cleaned.

4. Longitudinal stretching machine (1) according to one of the preceding claims, characterized in that the cleaning device (14) has at least one electric cleaning device motor and can be attached to and detached from the 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 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 / or can be moved parallel to the transverse extension (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.

5. Longitudinal stretching machine (1 ) according to claim 4, characterized in that a sensor unit (54) 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 viewed in the machine direction (M) in front of the 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).

6. Longitudinal stretching machine (1 ) according to one of the preceding claims, characterized in that the cutting device (22) is formed in the machine direction (M) 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) and in particular relative to the machine direction (M) between two guide rollers designed as transport rollers (12).

7. Longitudinal stretching machine (1 ) according to claim 6, characterized in that the roller (3) to be cleaned is one of the stretching rollers (6).

8. Method for operating a longitudinal stretching machine (1), in particular a longitudinal stretching machine (1) of a film extrusion plant, preferably according to one of claims 1 to 7, wherein the film web (2) is first heated by means of at least one heating roller (4) (102), subsequently stretched in a machine direction (M) by means of at least two stretching rollers (6) (104) and subsequently cooled by means of at least one cooling roller (8) and / or tempered by means of at least one annealing roller (8) (106), wherein the film web (2) is guided by means of guide rollers, characterized in that at least one of the guide rollers or the at least one heating roller (4) or one of the stretching rollers (6) or the at least one cooling roller (8) or the annealing roller (8) is cleaned by means of a The machine direction (M) is considered in front of the roller (3) to be cleaned, and the cutting device (22) is designed and can be inserted into and removed from the film web (2), in which the film web (2) is cut in the longitudinal direction (108), so that a cleaning gap (26) is formed, through which a cleaning device (14) is positioned against the roller (3) to be cleaned (110).

9. Method (100) according to claim 8, characterized in 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 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 roller (3) to be cleaned in such a way that the cleaning device (14) is always in engagement with the respective roller and is arranged within the cleaning gap (26) (114).

10. Method (100) according to claim 9, characterized in that, for cleaning the respective 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), in particular at least up to a first edge (62) of the maximum transverse extent (24) of the film web (2) (118) and subsequently moves out of the film web (2) (120), 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 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 of the roller (3), follows (122) and subsequently exits the cleaning gap (26) and / or moves away from the roller (3) to be cleaned (124).

11. Method (100) according to claim 10, characterized in that, for cleaning the respective roller, the cutting device (22) enters the film web (2) centrally to the transverse extent (24) of the film web (2) (128) and moves towards a second cutting direction (S2) parallel to the transverse extent (24) of the film web (2) 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 moves out of 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 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) of the 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 roller (3) to be cleaned (136).

12. Method (100) according to one of claims 8 to 11, characterized in that the cleaning device (14) is positioned against the roller (3) to be cleaned by means of at least one electric cleaning device motor and is positioned away from the roller (3) to be cleaned and is moved parallel to the longitudinal axis (46) of the roller (3) to be cleaned, preferably that the cutting device (22) is inserted into 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.

13. Method (100) according to claim 12, characterized in that a position of the cleaning gap (26) in the film web (2) in a section viewed in the machine direction (M) in front of the 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 such that the cleaning device (14) at least follows the position or course (R) of the cleaning gap (26) on the film web (2) (144).

14. Method (100) according to claim 13, characterized in that the cleaning device (14) moves through the cleaning gap (26) towards the roller (3) to be cleaned (142) when a cleaning gap (26) is detected and moves away from the roller (3) to be cleaned (146) when an end of the cleaning gap (26) is detected.

15. Method (100) according to any one of claims 9 to 14, characterized in 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) is synchronized with the movement of the Cutting device (22) corresponds, whereby a dead time is taken into account between the movements (152), which is calculated from a film travel time that a certain point on the film web (2) needs to be transported from the cutting device (22) to the cleaning device (14).

16. Film extrusion plant for the production of a film, comprising a longitudinal stretching machine (1) for stretching a film web (2) in a machine direction M, characterized in that the longitudinal stretching machine (1) has the features of at least one of claims 1 to 7.

Images