Film processing line for producing a plastic film web and method for cleaning components of film processing lines for producing a film web

Abstract

The invention relates to a film processing line for producing a plastic film web, in particular a cast film, calendar or blown film line, comprising the following features: a) the film processing line is provided with a machine unit along which the film web is transported via the film processing line; and b) the film processing line is provided with a roller unit that processes the film material; and c) the roller unit is provided with at least one film roller that is in contact with the film web; characterised by the following other feature: d) the film processing line is provided with a cleaning unit, with which a surface of at least one film roller of the roller unit in contact with the film web can be cleaned in an operating state. The invention also relates to a cleaning unit for a film processing line according to the invention, and methods for cleaning components of film processing lines for producing a film web.

Description

[0001] Film system for producing a plastic film web and method for cleaning components of film systems for producing a film web

[0002] Description

[0003] The invention relates to a film system for producing a plastic film web, in particular a cast film, calender or blown film system, a cleaning device for a film system and a method for cleaning components of film systems for producing a film web, in particular a cast film, calender or blown film system.

[0004] In film processing lines, deposits from the plastic melt ("plate-out") cause contamination on the roller surface. The contamination is formed from condensate or other substances released from the extrusion product. This has negative effects on the produced film, for example, variations in gloss or dullness, spots or streaks, and inclusions. This reduces the film quality and, in the worst case, renders the film unusable. Once a certain degree of contamination has been reached, cleaning and / or polishing is required.

[0005] It is known in the art that the roller(s) of the film line must be cleaned at regular intervals. However, thorough cleaning is only possible when the plant is at a standstill. This results in production downtime due to shutdown and start-up, as well as plant downtime, and requires personnel for cleaning.

[0006] The present invention is based on the object of providing an improvement or alternative to the prior art. In particular, the object of the invention is to enable a cleaning solution without manual intervention and, if possible, during operation of the film system.

[0007] According to a first aspect, the stated object is achieved by a film system for producing a plastic film web, in particular a cast film, calender, or blown film system, having the following features: a machine direction along which the film web is transported through the film system, a roller device that processes or guides film material, and at least one film roller in contact with the film web. Furthermore, the film system has a cleaning device by means of which a surface of at least one film roller of the roller device that is in contact with the film web can be cleaned in an operating state.

[0008] The following terminology is used to explain this:

[0009] It should be expressly pointed out that, within the scope of this patent application, indefinite articles and indefinite numerical expressions such as "one...", "two...", etc., are generally to be understood as "at least one...", "at least two...", etc., unless the context or the specific text of a particular passage indicates that only "exactly one...", "exactly two...", etc., are intended. Furthermore, all numerical expressions as well as information regarding process parameters and / or device parameters are to be understood in the technical sense, i.e., subject to the usual tolerances. Even the explicit specification of the restriction "at least" or "at least" or similar does not imply that the simple use of "one," i.e., without specifying "at least" or similar, means "exactly one."

[0010] In other words, the machine direction is understood to mean, in particular, a direction along which a raw material is processed into a film web. Within the scope of the present invention, a roller device preferably refers to a mechanical arrangement of at least one film roller, which in turn is designed to exert a shaping effect on the film web. The roller device can further comprise a corresponding electronic control device and a drive, such as a motor. Within the scope of the present invention, the term "operating state" can describe a state in which the film system is producing the film web, i.e., is active. Simply put, the operating state is thus, in particular, the state in which the film system is running, starting up, shutting down, or, in particular, when a roll change is being performed.In the context of the present invention, the cleaning device is to be understood in particular as a system designed to remove contaminants from the roller surface. Furthermore, the cleaning device can be designed to clean the film roller at regular intervals or continuously.

[0011] In one embodiment of the first aspect of the invention, the cleaning device is particularly designed to at least partially remove a coating on the surface of the film roller in contact with the film web. Within the context of the present invention, the term "removal" can preferably be understood to mean that contaminants are removed from the film roller, for example, by scraping, scratching, brushing, rubbing, or similar methods. Furthermore, the "removal" can also be carried out as a contactless removal of the contaminants from the film roller, for example, by evaporation, combustion, or the like, so that in this case there is no direct contact between an element of the cleaning device and the film roller. The film roller can have a desired coating, the so-called working coating, or no working coating at all.The coating can therefore include the optional working coating of the film roller. In other words, the unwanted coating can also be understood as adhesion or a deposit on the surface or on the optional working coating of the film roller.

[0012] For example, the cleaning device is also designed to at least partially transfer the coating to the film web. For this purpose, the coating can be initially collected or, alternatively, directed directly toward the film web. "Coating" refers in particular to the contamination on the film roller and, optionally, as already mentioned above, also to the working coating of the film roller. The working coating is preferably left on the film roller, while the contamination is removed and, if necessary, at least partially transferred to the film web.

[0013] It is conceivable for the cleaning device to have a cleaning element for contact-free removal of the coating. This particularly means that no element of the cleaning device is in contact with the film roller. It can be provided for the cleaning device to have a cleaning element for abrasive removal of the coating. In the context of the present invention, abrasive is to be understood in particular as meaning a rubbing, grinding effect which leads to smoothing, cleaning or wear. For this purpose, the cleaning device can be arranged in the immediate vicinity of the film roller and preferably have the cleaning element which is in contact with the film roller at least at intervals or continuously in order to carry out the abrasive removal of the coating on the film roller.For this purpose, the cleaning element can, for example, comprise at least one polishing element, a cloth or the like.

[0014] Furthermore, the cleaning element optionally comprises a laser designed to remove the coating. The laser is to be understood in particular as a laser system, which further comprises at least one controller and a suction device. The laser system can also have a beam expander, a mirror, and a focusing lens. The laser ensures, in particular, the vaporization, combustion, or melting of the coating, which in the latter case can be at least partially fed back into the film web.

[0015] It is possible for the laser to be designed as a pulsed laser with a frequency in a range between 50 kHz and 300 kHz, preferably between 150 kHz and 200 kHz. In addition, the laser in particular has a power, wherein the power is preferably between 2 W and 30 W. Alternatively, a more powerful laser can be provided, the power of which can be between 30 W and 100 W. In a preferred embodiment, the laser can have a laser power of 6 W to 10 W. In a preferred embodiment, the laser can be designed to adjust the power of the laser in a control range between 10% and 100% of the power. For this purpose, the laser can have a corresponding control system. At a frequency of 50 kHz, the laser in a specific embodiment has a pulse energy of 1 mJ. The pulse energy is in particular directly proportional to the average power and inversely proportional to the repetition rate of the laser.Furthermore, the laser preferably has a wavelength in the range between 400 nm and 1200 nm, in particular between 1055 nm and 1070 nm. Alternatively, it is also conceivable for the laser to be designed as a continuous laser, i.e. as a continuous wave laser. Furthermore, the frequency and / or the number and strength of the power levels as well as the wavelength of the selected laser can vary depending on the specific application in order to ensure that the film roller is cleaned without destroying it. In the context of the invention, a pulsed laser is understood to mean in particular a laser that does not emit light continuously, but is operated in pulsed mode, i.e. emits the light in time-limited portions. The wavelength of the laser describes in particular the spatial frequency of the emitted light wave. The optimal wavelength for a specific application depends essentially on the respective application. The power of the laser, i.e.the respectively selected power level of the laser, is understood in the context of the present invention to mean in particular an optical output power of a continuous wave (CW) laser or an average power of a pulsed laser. A pulsed laser has a specific pulse duration, which is defined as the half-width of the optical power of the laser over time. The pulse duration in the context of the present invention is preferably between 100 ns and 140 ns. Thus, the laser can alternatively also be designed as an ultrashort pulse laser, which has pulse durations in the order of magnitude of picoseconds to attoseconds. In the context of the present invention, the frequency is preferably understood to mean the pulse repetition frequency of the pulsed laser, which describes the number of emitted pulses per second or the inverse of the temporal pulse interval. The light of the laser is preferably randomly polarized, so that emitted electric fields point in random directions.Alternatively, the laser light can also be linearly polarized, so that the emitted electric fields consistently point in the same direction. Furthermore, the laser has a specific beam diameter, which specifically characterizes the transverse extent of the beam or the physical size of the beam perpendicular to the propagation direction. The beam diameter determines the power / energy density or the optical power / energy per unit area of ​​a laser beam. The larger the beam diameter, the smaller the power / energy density of a beam with constant power or energy. Furthermore, the laser has a beam profile, which describes the intensity distribution across a cross-section of the beam. Common beam profiles include, for example, Gaussian and flat-top beams, whose beam profiles are Gaussian or rectangular, respectively.In addition, the laser has the property of divergence, which describes a broadening of a beam with increasing distance in relation to a beam waist of the laser due to diffraction and is defined by a half-angle of the laser. Another characteristic property of the laser is a spot size, which describes a beam diameter at the focal point of a focusing lens system. To maximize the power density, the spot size should preferably be as small as possible. For example, aspheric lenses can be used instead of conventional spherical lenses to reduce spherical aberrations and create smaller spot sizes. There is a so-called working distance between the laser, or rather between the last optical element of the laser, and the object, for example the coating on the surface of the foil roller.

[0016] In another possible embodiment according to the first aspect of the invention, the cleaning element comprises a steam applicator designed to remove the coating with steam. The steam applicator is designed, for example, as an electric steam generator that can provide steam at adjustable temperatures and pressures. For this purpose, the steam applicator can further comprise a corresponding control device.

[0017] The vapor can also be water vapor. Alternatively, the vapor can be a solvent from the group of aprotic solvents, protic solvents, and indifferent solvents. The use of a solvent can promote the removal of the coating. An organic solvent such as acetone can be used as the solvent, although the choice of solvent depends on the material of the film web.

[0018] In another embodiment, the cleaning element comprises a plasma jet designed to remove the coating. The term plasma refers in particular to a gas that consists partially or entirely of free charge carriers, i.e., ions or electrons. Accordingly, the plasma jet preferably blasts said gas onto the film roller to at least partially remove the coating.

[0019] Furthermore, it can be provided that the cleaning device has an applicator for cleaning agents for application to the surface and / or the coating on the surface of the at least one film roller in contact with the film web. Within the scope of the present invention, a solvent such as acetone, a polishing paste and / or water is provided as the cleaning agent. The applicator can furthermore have a control system in order to apply the cleaning agent at intervals or at specific times to the surface or the coating on the surface of the at least one film roller in contact with the film web. Alternatively, the applicator can apply the cleaning agent continuously to the surface or the coating on the surface of the at least one film roller in contact with the film web.

[0020] For example, the cleaning device is designed as a cleaning unit having a housing, and the cleaning unit forms a mobile unit which can be moved to clean surfaces of a plurality of film rollers of the roller device that are in contact with the film web. For this purpose, the cleaning unit can have a rail and / or a mounting system as well as a control system in order to move the cleaning unit between the film rollers of the roller device that are in contact with the film web. It is conceivable within the scope of the present invention for the cleaning device or the cleaning unit to have a plurality of cleaning elements, each of which is arranged on or near one of the plurality of film rollers of the roller device that are in contact with the film web, in order to enable simultaneous, alternating or randomly performed cleaning of the film rollers.It is also possible for multiple cleaning elements to be provided for cleaning a single film roller. The multiple cleaning elements can be the same type of cleaning element, e.g., abrasive or non-contact, or a combination of different types of cleaning elements.

[0021] According to a second aspect of the invention, the stated object is achieved by a cleaning device for the film system according to the invention.

[0022] According to a third aspect of the invention, the stated object is achieved by a method for cleaning components of film systems for producing a film web, in particular cast film, calender, or blown film systems, comprising the following steps: providing a film system, providing a roller device that processes or guides a film material and has at least one film roller in contact with the film web, and providing a cleaning device by means of which a surface of at least one film roller of the roller device that is in contact with the film web can be cleaned in an operating state. Furthermore, cleaning of the at least one film roller of the roller device that is in contact with the film web is carried out in an operating state by at least partially removing a coating on the at least one film roller.This is carried out using a cleaning element which can be an abrasive or a non-contact cleaning element. The application time of the cleaning element can be varied for cleaning. If a laser is to be used for cleaning, the laser application time can be between 30 and 90 seconds, in particular between 50 and 70 seconds. Optionally, the removed coating can also be partially or completely returned. The removal can be carried out up to the optional working coating of the at least one film roller, or the working coating can be partially or completely removed. If no working coating is present, the removal can partially or completely remove the coating.

[0023] It is also possible for the cleaning to be performed as a traversing movement or as a full-surface cleaning. In other words, a traversing movement means that the cleaning element only partially covers the surface of the film roller axially, and the surface is therefore cleaned by moving back and forth. With full-surface cleaning, the cleaning element completely covers the entire axial width of the surface of the film roller and therefore does not need to be moved to completely clean the surface of the film roller.

[0024] The invention will be explained in more detail below using exemplary embodiments with reference to the drawings. Fig. 1 shows a schematic representation of the roller device with an abrasive cleaning element

[0025] Fig. 2 shows a schematic representation of the roller device with a laser as a cleaning element

[0026] Fig. 3 shows a schematic representation of the roller device with a

[0027] Steam applicator as a cleaning element

[0028] Fig. 4 shows a schematic representation of the roller device with a

[0029] Plasma lamp as a cleaning element

[0030] Fig. 5 shows a schematic representation of the roller device with a laser as a cleaning element and additionally with an applicator

[0031] Figure 1 shows a schematic representation of a roller device 3 according to the invention, which is part of a film system 1 (not shown) and which, in this exemplary embodiment, has three film rollers 31. The film rollers 31, in turn, have a surface 311 on which a coating 5 accumulates during operation of the film system 1. The film web 2 is shaped between the film rollers 31. Also shown is the machine direction MD, which represents the direction in the film system 1 from a raw material to a finished film web. Here, by way of example, a cleaning device 4 is also arranged on the first film roller 31. It is also conceivable within the scope of the invention for the cleaning device 4 to be arranged on the second or third or on all of the film rollers 31 present.Furthermore, the cleaning device 4 comprises a cleaning element 7, which in this embodiment is designed as an abrasive cleaning element 7.

[0032] Figure 2 differs from the arrangement in Figure 1 only in that the cleaning element 7 is designed as a laser 71 and thus as a non-contact cleaning element 7. The laser beams which act on the coating 5 on the surface 311 of the film roller 31 are shown in dashed lines. The laser 71 is a pulsed laser with a frequency in a range between 150 kHz and 200 kHz. The laser 71 also has two power levels, the first power level being between 10 W and 30 W, and the second power level between 30 W and 100 W. In addition, the laser 71 has a wavelength in the range between 400 and 1200, in particular 1064 nm.

[0033] In contrast to Figures 1 and 2, Figure 3 has a steam applicator 72 as the cleaning element 7, which, shown by dashed lines, applies a steam 721 in the form of water vapor to the coating 5 on the surface 311 of the film roller 31. An alternative application of a solvent would also be conceivable.

[0034] Figure 4 again shows the arrangement of the roller device 3 from Figure 1, except that in this embodiment a plasma jet 73 is used as the contact-free cleaning element 7.

[0035] Figure 5 schematically shows a further embodiment of the invention. Here, the cleaning device 4 is designed as a cleaning unit and has a housing 41. Furthermore, the cleaning unit comprises a cleaning element 7 in the form of a laser 71 and an applicator 8 for applying cleaning agent 81 to the surface 311 of the film roller 31. In this exemplary embodiment, the cleaning unit is located on a rail 9, so that the cleaning unit can be moved to the third film roller 31 for cleaning it. The rail 9 is intended to only sketchily represent the inventive idea that the cleaning unit, in one embodiment, can be mobile and movable between the film rollers 31.

[0036] The embodiments shown here are merely examples of the present invention and should therefore not be construed as limiting. Alternative embodiments contemplated by those skilled in the art are equally encompassed within the scope of the present invention. List of reference symbols used

[0037] 1 film system

[0038] 2 film strips

[0039] 3 roller device

[0040] 31 foil roller

[0041] 311 Surface

[0042] 4 Cleaning device

[0043] 41 housings

[0044] 5 Coating

[0045] 7 Cleaning element

[0046] 71 lasers

[0047] 72 Steam applicator

[0048] 721 Steam

[0049] 73 plasma lamps

[0050] 8 Applicator

[0051] 81 cleaning products

[0052] 9 Rail

[0053] MD Machine direction...

Claims

Claims 1. Film system (1) for producing a plastic film web (2), in particular a cast film, calender or blown film system, having the following features: a. the film system (1) has a machine direction (MD) along which the film web (2) is transported through the film system (1), and b. the film system (1) has a roller device (3) that processes or guides film material, and c. the roller device (3) has at least one film roller (31) that is in contact with the film web (2), characterized by the following further feature: d. the film system (1) has a cleaning device (4) by means of which a surface (311) of at least one film roller (31) of the roller device (3) that is in contact with the film web (2) can be cleaned in an operating state.

2. Film system (1) according to claim 1 with the following further feature: a. the cleaning device (4) is designed to at least partially remove a coating (5) on the surface (311) of the film roller (31) in contact with the film web (2).

3. Film system (1) according to one of the preceding claims with the following further feature: a. the cleaning device (4) is designed to transfer the coating (5) at least partially to the film web (2).

4. Film system (1) according to one of the preceding claims with the following further feature: a. the cleaning device (4) has a cleaning element (7) for contact-free removal of the coating (5).

5. Film system (1) according to one of the preceding claims 1 to 3 with the following additional features: a. the cleaning device (4) has a cleaning element (7) for abrasive removal of the coating (5).

6. Film system (1) according to one of the preceding claims with the following further features: a. the cleaning element (7) comprises a laser (71) which is designed to remove the coating (5).

7. Film system (1) according to claim 6 with at least one of the following additional features: a. the laser (71) is designed as a pulsed laser, preferably with a frequency in a range between 50 kHz and 300 kHz, preferably between 150 kHz and 200 kHz.

8. Film system (1) according to claim 6 with at least one of the following additional features: a. the laser (71) has a power, wherein the power is in particular between 2 W and 30 W.

9. Film system (1) according to claim 6 with at least one of the following additional features: a. the laser (71) has a wavelength in the range between 400 and 1200, in particular between 1055 nm and 1070 nm.

10. Film system (1) according to one of the preceding claims with the following further features: a. the cleaning element (7) comprises a steam applicator (72) which is designed to remove the coating (5) with a steam (721).

11. The film system (1) according to claim 10, having at least one of the following additional features: a. the vapor (721) is water vapor. b. the vapor (721) is a solvent selected from the group consisting of aprotic solvents, protic solvents, and indifferent solvents.

12. Film system (1) according to one of the preceding claims with the following further features: a. the cleaning element (7) comprises a plasma emitter (73) which is designed to remove the coating (5). Film system (1) according to one of the preceding claims, with the following additional features: a. the cleaning device (4) has an applicator (8) for cleaning agents (81) for application to the surface (311) and / or the coating (5) on the surface (311) of the at least one film roller (31) in contact with the film web (2). Film system (1) according to one of the preceding claims, with the following additional features: a. the cleaning device (4) is designed as a cleaning unit (7) having a housing (41), and b. the cleaning unit (7) forms a mobile unit, which is movable for cleaning surfaces (311) of a plurality of film rollers (31) of the roller device (3) in contact with the film web (2). Cleaning device (4) for a film system (1) according to one of the preceding claims.Method for cleaning components of film systems (1) for producing a film web (2), in particular a cast film, calender or blown film system, comprising the following steps: a. providing a film system (1), b. providing a roller device (3) which processes or guides a film material and which has at least one film roller (31) in contact with the film web (2). c. Providing a cleaning device (4) by means of which a surface (311) of at least one film roller (31) of the roller device (3) that is in contact with the film web (2) can be cleaned in an operating state, d. Cleaning the at least one film roller (31) of the roller device (3) that is in contact with the film web (2) in an operating state by at least partially removing a coating (5) on the at least one film roller (31). Method according to claim 16, with the following further step: a. Partially or completely returning the removed coating (5). Method according to claim 16 or 17, wherein the cleaning is carried out as a traversing movement or as a full-surface cleaning.

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