Cleaning system of moving element of coating installation, associated coating machine, coating installation and method

Abstract

To provide a system configured to enhance efficiency of a coating machine.SOLUTION: There is provided a cleaning system configured to clean an outer surface of a roller of a coating machine 10 configured to coat and / or print and / or shape a layer on a web. The cleaning system comprises: a robotic arm comprising a gripper; a cleaning device attached onto the gripper and configured to clean an outer surface of the roller; and a command unit configured to command the robotic arm and the cleaning device to carry out a cleaning task of a part of the outer surface. The command unit is configured to: receive at least one defect property; and trigger a cleaning task in accordance with each received defect property. Therein the defect property is a property of at least one defect of the layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a cleaning system adapted to clean the outer surfaces of moving elements of a coating installation, in particular rollers. Furthermore, the present invention proposes a coating machine or coating installation equipped with the cleaning system. Furthermore, the present invention relates to a method for cleaning the outer surfaces of moving elements of a coating installation. [Background technology]

[0002] Coating machines are used to treat moving webs. One common technique for treating webs is coating. Such a technique requires the use of at least one coating machine.

[0003] Such coating machines are associated with coating processes that use rollers to apply, treat, coat, print, laminate, or form a chemical composition onto a web. Additionally, such coating machines may include rollers for driving, conveying, or transporting the web. While such coating processes are typically capable of achieving coating speeds of 100 m / min up to 1000 m / min, this coating speed is often impacted by the poor quality of the coated web film. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 4,270,483 [Patent Document 2] U.S. Patent No. 3,851,582 [Patent Document 3] U.S. Patent No. 5,176,077 [Patent Document 4] U.S. Patent No. 10,040,101 [Patent Document 5] U.S. Patent No. 11,192,149 Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, a need exists for a system configured to increase the efficiency of a coating machine. [Means for solving the problem]

[0006] To this end, the present disclosure relates to a cleaning system adapted to clean the moving elements, in particular the outer surfaces of the rollers, of a coating installation, the coating installation comprising a coating machine adapted to coat and / or print and / or form a layer on a web, the cleaning system comprising: a robotic arm having a gripper; - a cleaning device mounted on the gripper, the cleaning device being configured to clean an outer surface of the movable element; - a command unit configured to command the robot arm and the cleaning device to perform a cleaning task on a portion of the outer surface of the mobile element; Equipped with A cleaning system is described in which the command unit is configured to receive at least one defect characteristic and initiate a cleaning task according to each received defect characteristic, the defect characteristic being a characteristic of at least one defect in the layer.

[0007] Such a cleaning system allows for a higher efficiency of the coating equipment by reducing malfunctions, thereby resulting in process improvements. The development of this cleaning system was made possible by a research program carried out by the Applicant.

[0008] This research program leading to the present invention and the various problems that were solved are discussed below.

[0009] In practice, very high speed coating machines (typically 400 m / min up to 1000 m / min coating speed) are used that use multiple cylinders to coat thin layers of solvent-based coating compositions onto thin PET webs. Typically, the web thickness is less than 5 μm for plastic webs, and the weight basis of the coated layer is less than 1 g / m 2 (but 0.5g / m 2 The following may be the goal:

[0010] The efficiency of such coating machines is affected by several factors which must be reduced.

[0011] Specifically, it is desirable to remove contaminants / impurities, soiling, and ink residue from the cylinders (rollers) used during the web coating process.

[0012] In certain coating processes, a coating composition is applied to a moving web by transferring the liquid coating composition from an application roller to the web. In this type of process, a counter roller (or backup roller) is used to either transport the web or meter the liquid coating composition into the nip formed between the two rollers, or both. The counter roller is often called a "sleeve" because it is covered with a soft, smooth, elastic cover. During coating, the sleeve can become stained. Sleeve fouling has a direct impact on the quality of the coated web.

[0013] At that point, manual cleaning with abrasive pads is not sufficiently effective in removing fouling, such as dirt, dust, solid particles, and especially dried ink droplets. Operators must intervene to clean the cylinder after detecting the defect, thus creating additional delays and increasing safety risks. Furthermore, the entire coating facility must be shut down to remove ink droplets resulting from the machine's acceleration phase, negating the benefits of the initial acceleration phase of production.

[0014] All these considerations have led the applicant to consider the entire coating process and determine that the cleaning process is a critical point for the following reasons:

[0015] Automating the cleaning process improves quality, safety, and productivity.

[0016] In certain productions of webs coated using solvent-based, highly flammable coating compositions, the coating system must comply with ATEX standards, and therefore the cleaning system is located in an explosion-proof atmosphere. The cleaning environment is therefore subject to restrictions due to the presence of highly flammable solvents, which poses an increased risk of explosion due to friction against the backup roll and the use of cleaning solvents.

[0017] One purpose is to control the cleaning process (controlling friction and rubbing action), especially in ATEX environments. One benefit is lower risk of sparks and reduced spillage of highly flammable solvents.

[0018] However, this cleaning process should also offer other benefits in non-ATEX atmospheres.

[0019] Another objective is to control the coating stage by reducing the number of production stops, avoiding operator intervention on the rotating cylinders (also called rolls or rollers), and improving the efficiency of the entire process.

[0020] Yet another objective is to increase operator safety and avoid carrying heavy loads.

[0021] In particular, operations such as transporting or handling rollers, for example to clean the rollers / cylinders offline, should be avoided.

[0022] Such cleaning systems are designed to automatically clean cylinders used in coating processes, which may be rollers fitted with elastomeric sleeves and which can reach maximum rotational speeds of up to 3200 rpm (revolutions per minute).

[0023] The primary contaminants are dry materials such as waxes, resins, additives, and pigments, and solvents such as 100 / 140 gasoline, toluene, ethyl acetate, and methyl ethyl ketone (MEK) may be used for cleaning.

[0024] Additionally, a semi-solid or solid substance, such as a gel or cream, may be used to wipe the sleeve. Additionally, static dissipative additives may be added to the cleaning product.

[0025] Since the elements being cleaned are in motion, it is difficult to assess the level of fouling during coating. One objective is to clean the cylinders during high-speed production without frequent line shutdowns and while ensuring operator safety.

[0026] Therefore, one objective of the research project was to robotize this cleaning step, thereby eliminating the need for an operator to intervene with the rotating cylinder or to stop production for in-line or off-line roll cleaning. The data used to feed the cleaning operation may be obtained from a control camera or from any other in-line control system, such as an in-line coating weight control unit.

[0027] The result is a cleaning system designed to effectively minimize defects caused by dirty cylinders in coating and / or printing and / or forming layers onto a web.

[0028] These defects caused by dirty cylinders are unique and different from other types of defects, such as defects in paper manufacturing. Specifically, such defects are repetitive defects with the distance between each defect corresponding to the circumference of the cylinder. Examples include ink voids, streaks, excessive thickness, or smudging.

[0029] According to other aspects of the cleaning system, which are advantageous but not required, the cleaning system may incorporate one or more of the following features in any technically acceptable combination. The cleaning system further comprises an analysis unit, which analysis unit comprises: - configured to receive data from the sensor, the data being an image of the layer coated and / or printed by the coating machine, and further the analysis unit - configured to detect at least one defect characteristic of at least one defect in the layer by analyzing said data. - the cleaning device comprises an interface unit configured to receive information from a user regarding at least one defect in the layer, and a command unit configured to command the robot arm and the cleaning device also according to the information regarding the at least one defect in the layer. At least one defect characteristic detected by the analysis unit is whether or not a defect is present. - Each defect is associated with a defect severity, and one defect characteristic is the defect severity. The command unit is configured to initiate a cleaning task if the defect severity of the detected defect exceeds a predetermined defect severity. Each defect in the layer belongs to a respective predetermined defect group, a defect characteristic is the defect group to which the defect belongs, and area characteristics of the area to be cleaned by the cleaning device are selected according to said defect characteristic. One area characteristic is the surface of the area to be cleaned. One area characteristic is the localization of the center of the area to be cleaned, which is preferably selected from among three zones: the left part of the moving element, the middle part of the moving element, and the right part of the moving element. The cleaning task is characterized by cleaning parameters, the command unit being configured to calculate each cleaning parameter depending on the defect characteristics. The cleaning device comprises a cleaning pad configured to contact a portion of the outer surface of the movable element, the cleaning pad preferably having an outer surface with foam, the foam being in particular melamine foam. The cleaning device further comprises a cleaning pad, a solvent reservoir, and a pressure unit, the pressure unit being configured to deliver solvent from the solvent reservoir to the cleaning pad.

[0030] Furthermore, the present description relates to a coating machine equipped with a cleaning system as described above.

[0031] Further, this specification describes a coating installation that includes a cleaning system as described above.

[0032] The present disclosure further provides a method for cleaning the outer surfaces of moving elements, in particular rollers, of a coating installation, the coating installation comprising a coating machine configured to coat and / or print and / or form a layer on a web, the method comprising: a robotic arm having a gripper; a cleaning device mounted on the gripper, the cleaning device being configured to clean an outer surface of the movable element; - a command unit configured to command the robot arm and the cleaning device to perform a cleaning task on a portion of the outer surface of the mobile element; The cleaning system is implemented by The method is: - receiving at least one defect characteristic, the defect characteristic being a characteristic of at least one defect in the layer; - initiating a cleaning task according to each received defect characteristic; The present invention relates to a method, including:

[0033] The invention will be better understood on the basis of the following description, given by way of example and in correspondence with the accompanying drawings, in which: FIG. [Brief explanation of the drawings]

[0034] [Figure 1] FIG. 1 is a side view of a coating facility. [Figure 2] FIG. 1 is a diagram of a representative example of a coating machine involved in the coating process. [Figure 3]FIG. 1 is a schematic diagram of a cleaning system. [Figure 4] FIG. 1 is a schematic diagram of an implementation of a particular coating process. [Figure 5] FIG. 1 is a schematic diagram of an implementation of a particular coating process. [Figure 6] FIG. 1 is a schematic diagram of an implementation of a particular coating process. [Figure 7] FIG. 1 is a schematic diagram of an implementation of a particular coating process. [Figure 8] FIG. 1 is a schematic diagram of an implementation of a particular coating process. DETAILED DESCRIPTION OF THE INVENTION

[0035] A coating installation 5 is shown diagrammatically in FIG.

[0036] This coating installation 5 is configured to carry out a process for coating, which process entails the use of any necessary machines that are part of the coating installation 5.

[0037] More precisely, the process for coating comprises at least the following steps in this order: unwinding the web, coating it, and finally unwinding it.

[0038] One or more optional steps may be added between the coating and unwinding steps to harden the coated layer by cooling, drying, curing, or otherwise forming the coating composition.

[0039] Accordingly, the coating installation 5 comprises at least an unwinder 6 , an unwinder 7 and a coating machine 10 .

[0040] The unwinder 6 and the rewinder 7 are configured to unwind and rewind the spool of web at a given speed, respectively.

[0041] Depending on the coating technique chosen, a dryer 8 and / or a curer 9 are often required.

[0042] Dryer 8 and curer 9 are configured to perform film-forming or dry-coating techniques by converting the liquid coating applied to the web into a solid coating. Depending on the end use of the coated web, this coating may be tack-free or may remain tacky. Protective films or spacers may be added to prevent coil-to-coil binding and to allow for unwinding of the spool.

[0043] Examples of techniques utilized during film formation are heat transfer using temperature controlled rollers or air blowers, infrared heating, ultraviolet curing, and electron beam radiation.

[0044] Coating machine 10 is a machine configured to coat and / or print and / or form a layer onto web 12 .

[0045] Web refers to any film, foil, sheet, or the like, whose length and / or width dimensions exceed its thickness dimension by at least 10 or 100 times.

[0046] The web may be any long, thin, flexible structure, such as paper, film, foil, nonwoven, fiber, plastic film, metal foil, impregnated fiber, prepreg, etc. Optionally, the web has a flat and / or flexible surface.

[0047] Such flat webs may be made of any type of material, such as metal, glass, paper, fabric, leather, plastic, particles, etc., plain, laminated, or any combination of mixtures. The flat webs may be plain, rough, smooth, or have a large mesh, such as a net. The flat webs may be made of polymers, such as polyester or polyimide. The flat webs may be aluminum or copper foils. The flat webs are intended to be coated, laminated, embossed, or printed. The flat webs may be multi-layer webs, i.e., pre-coated webs or laminates.

[0048] Preferably, the flat web is designed and / or intended to be coated, printed, chemically treated, cut, slit, sliced, wound and / or unwound, solidified or dried. The other, uncoated side is intended to be in contact with the outer surface of the roller system for cleaning (counter roller 17). Furthermore, the flat web may result from a shaped manufacturing process, such as cast film, blown film, or extruded film.

[0049] Optionally, the flat web is a band.

[0050] The flat web may be a drive belt. The flat web may be used to convey an object or to drive an element in rotation.

[0051] Generally, the coating equipment 5 disclosed herein may comprise any type of covering machine known to those skilled in the art, such as but not limited to a coating, printing press, or machine for, for example, a calendaring or laminating operation.

[0052] The coating facility may include one or more coating machines for performing any coating technique as a single coating technique or in combination.

[0053] Well-known techniques include, for example, gravure coating, porous roll coating, rotary screen printing, flexography, calendering, laminating or embossing.

[0054] Next, some specific examples will be described in detail.

[0055] Further information regarding the implementation of the coating installation 5 can be obtained from the documents US Pat. No. 4,270,483, US Pat. No. 3,851,582 and US Pat. No. 5,176,077, among others.

[0056] In FIG. 2, an example of a coating machine 10 is shown schematically.

[0057] The coating machine 10 comprises an ink reservoir 13 , a coating element 14 , a coating roller 16 , a counter roller 17 , and a cleaning system 20 .

[0058] In this example, ink is selected as one specific possibility for the coating composition.

[0059] Coating roller 16 , also referred to as an applicator roller, may be an engraved roller configured to coat and / or print and / or cover a portion of web 12 with a desired coated layer 15 .

[0060] In this case, a coating roller 16 applies ink supplied by an ink reservoir 13 onto the web 12 .

[0061] The metered amount of coating from the reservoir 13 onto the coating roller 16 is ensured by a coating element 14, for example a doctor blade.

[0062] Each of the rollers 16 and 17 is a rotating roller.

[0063] The counter roller 17 may be part of a roller assembly.

[0064] The roller assembly is configured to allow movement of a web 12, which is intended to be coated with a coating layer.

[0065] Counter roller 17 may be a drive roller and may drive web 12 through the coating machine.

[0066] Additionally, the counter roller 17 may be an idle roller, the rotation of which is secured by the web. In either case, the counter roller 17 handles the web 12 on its outer surface 22, thereby pulling the web 12 or metering the coated layer 15.

[0067] The coating installation 5 further comprises a sensor 18 .

[0068] The sensor 18 may be positioned anywhere within the coating installation 5, preferably the sensor 18 is located before the unwinder 7 at the end of the coating installation.

[0069] Sensor 18 is a sensor configured to capture images or collect data of a coating layer applied to web 12 by coating machine 10 .

[0070] The data may be a defect mapping of the web 12 .

[0071] As will become apparent from the examples given above, the data collected or acquired by the sensors 18 corresponds to quality data.

[0072] In particular, the sensor 18 may be capable of detecting primary and secondary defects.

[0073] The purpose of the sensor 18 is to detect the effects of fouling on the web, not to correct the fouling.

[0074] To this end, various types of sensors can be used.

[0075] For example, according to this example, the sensor 18 is a camera vision system, which may be one or more cameras.

[0076] This type of sensor can capture the entire web using a linear camera.

[0077] With other types of sensors, it may be necessary to have multiple sensors to cover the entire width of the web with sufficient detail.

[0078] Furthermore, the sensor 18 may be adapted to the material used, so as to be effective in detecting small dimensional defects.

[0079] Data collected by the sensor 18 may include location related defects that are transmitted to the cleaning system 20 .

[0080] Other types of sensors may be used, each with different technologies and detection systems.

[0081] For example, a scanning system such as an online coating weight gauge can be used, which can use, for example, an X-ray sensor or an ultrasonic sensor, and can be a transmission type sensor, a reflection type sensor, or both.

[0082] It is also possible to use interferometry, which uses the interference of waves to extract information.

[0083] This is not a comprehensive list and many types of sensors 18 exist and may be considered.

[0084] It is possible to use at least one visual sensor, but it is also possible to use capacitance sensors, frequency sensors, air pressure sensors such as those used to detect rubber defects, or other sensors adapted to the product and process used.

[0085] The type of detection is determined by the product parameters that are affected by the fouling.

[0086] Preferably, a camera vision system is used because of its versatility, although defect detection may also be performed by an operator.

[0087] The use of sensors is optional, and if required, the type of sensor is selected based on product and / or process characteristics.

[0088] The data collected by the sensors 18 may include, for example, thickness, color change, surface structure, electrical parameters, geometric parameters, or any other process output. In complex cases, it may be necessary to combine multiple types of sensors or detection systems to detect the effects of fouling on the web.

[0089] In the case of FIG. 3, the cleaning system 20 comprises an analysis unit 28 .

[0090] In other embodiments, analysis unit 28 may not be present, particularly if the output of analysis unit 28 is obtained by another technique, such as by an operator.

[0091] In such a case, cleaning system 20 includes an interface unit configured to receive at least one defect characteristic from an operator.

[0092] For purposes of illustration, the following description will be limited to the case where the analysis unit 28 is present.

[0093] In one embodiment, the analysis unit 28 is connected to the sensor 18 and drives the cleaning system 20 by analyzing the data output of the sensor 18. In one embodiment, the sensor 18 is capable of detecting and recognizing defects according to parameters recorded in a database or using a calculator.

[0094] The analysis unit 28 is configured to receive data from the sensor 18. In this case, the received data is an image of the layer coated and / or printed by the coating machine 10.

[0095] The analysis unit 28 is configured to analyze the data to detect and recognize at least one defect characteristic.

[0096] The cleaning system 20 further comprises a robotic arm 24 , a cleaning device 26 , and a command unit 30 .

[0097] The robot arm 24 includes a gripper 32 .

[0098] The cleaning device 26 is configured to clean the outer surface 22 of the roller 17 .

[0099] Additionally, the cleaning device 26 may be used to clean temperature-controlled rollers. Because high or low temperatures may be used, which may accelerate solidification of the coating composition on the area to be cleaned and make the cleaning process more difficult (faster ink solidification, or ink melting and spreading of stains, etc.), the cleaning device 26 may be equipped with adapted cleaning aids.

[0100] More generally, cleaning device 26 is configured to clean the area to be cleaned.

[0101] "Cleaning" in this context means that the cleaning device 26 is configured to clean this area (synchronously with the sensor 18 and the analysis unit 28) until cleaning of this area is complete or at least until the associated defects are completely removed.

[0102] Furthermore, the cleaning device 26 may be configured to partially clean this area until the associated defects are adequately removed according to quality standards.

[0103] Such areas to be cleaned are characterized by area properties.

[0104] For example, the localization of the center of the area to be cleaned is an area characteristic.

[0105] Such localization may be simplified as a left side portion of the outer surface 22, a central portion of the outer surface 22, and a right side portion of the outer surface 22.

[0106] Another example of an area characteristic is the size of the area to be cleaned.

[0107] According to the example described, the cleaning device 26 comprises a cleaning pad 34 configured to contact a portion of the outer surface 22 of the roller 17 .

[0108] Such cleaning pads 34 having an outer surface 36 may be provided with fabric, foam, or any other material capable of absorbing or retaining liquid therein.

[0109] Preferably, the foam is a melamine foam.

[0110] Preferably, the fabric is a fabric comprising microfibers.

[0111] The cleaning pad 34 may be constructed from one or more of polyester, polyamide (nylon), wood pulp, cellulose, or cellulose fibers.

[0112] Cleaning may be performed by wiping and scrubbing the outer surface 22 of the roller 17 with a dry or solvent soaked pad.

[0113] The cleaning system 20 may further include a solvent reservoir 38 and a pressure unit 40. The pressure unit 40 may be configured to pump or direct solvent from the solvent reservoir 38 to the cleaning pad 34.

[0114] Additionally, the solvent reservoir 38 may be disconnected from the cleaning system 20. If the solvent reservoir is separate from the cleaning system, the cleaning system 20 may immerse the cleaning pad 34 in the solvent reservoir 38 to extract the solvent.

[0115] The cleaning device 26 is mounted on a gripper 32 of the robotic arm 24 .

[0116] The command unit 30 is configured to command the robot arm 24 and the cleaning device 26 to perform a cleaning task on a portion of the outer surface 22 of the roller 17 .

[0117] A cleaning task may represent a single operation, multiple operations, or even multiple repetitive operations that form a cleaning cycle.

[0118] Additionally, the command unit 30 can control the amount of solvent dispensed onto the cleaning pad 34 to deliver a regulated amount of solvent.

[0119] Each cleaning task is characterized by cleaning parameters.

[0120] The cleaning parameters are, for example, as follows: - the pressure applied to perform the cleaning, - atomization time of cleaning products, - the interval between two atomizations, - the type of ink used for the layer, - the type of solvent used, - the technology used by the coating machine, and - Number of cycles (if relevant).

[0121] The cleaning parameters may be stored in a database that contains a list of defect characteristics.

[0122] A defect characteristic is a characteristic of at least one defect in the layer.

[0123] For example, the defect characteristic is the presence or absence of a defect.

[0124] According to another example, the defect characteristic is the defect severity of the defect.

[0125] In this case, it is expected that each defect will be associated with a respective degree of defect, for example, degree 0 being no defect, degree 1 being a slight defect, degree 2 being a serious defect, and degree 3 being an extremely serious defect.

[0126] In certain embodiments, cleaning system 20 may be configured to select whether or not to clean a portion of outer surface 22 of roller 17 based on the severity of the defect.

[0127] According to another view, a number of defect groups are defined and each defect in the layer belongs to one of these defect groups.

[0128] The defect characteristic is therefore the defect group to which the defect belongs.

[0129] For example, a defect group may be a group determined by a size range, with one specific example being small size defects, medium size defects, and large size defects.

[0130] Similar defect groups may be used along with appearance and / or size.

[0131] Additionally, defect groups may be created according to the criticality of the defects.

[0132] The criticality of such defects is typically defined based on the user's quality criteria.

[0133] More generally, a defect group may be a combination of multiple defect characteristics and may be linked to the criticality, severity, or seriousness of the defect or malfunction.

[0134] To achieve such a classification operation, the analysis unit 28 implements, for example, a neural network.

[0135] In a variant or supplementary example, the analysis unit 28 may be equipped with self-learning capabilities.

[0136] In one embodiment, analysis unit 28 is configured to automatically rank the defects and assign the defects to corresponding defect groups.

[0137] Thus, the analysis unit 28 is configured to process the data received from the sensor 18 according to the defect characteristics.

[0138] The command unit 30 is configured to receive at least one defect characteristic.

[0139] In this case, the command unit 30 receives at least one defect characteristic from the analysis unit.

[0140] The command unit 30 is configured to initiate a cleaning task according to each received defect characteristic.

[0141] Such operation of the command unit 30 will now be described with some specific use cases.

[0142] As a first example, the command unit 30 initiates cleaning tasks according to the defect degree.

[0143] For example, the command unit 30 initiates a cleaning task only if the defect severity of the detected defect exceeds a predetermined defect severity.

[0144] As another example, the command unit 30 selects at least one region characteristic depending on a defect group to which the detected defect belongs.

[0145] In another example, areas to be cleaned can be targeted according to defects. A cleaning "mission" is given to the cleaning system. The vision initiates the mission and stops the mission once the obstacle is gone.

[0146] The area to be cleaned is precise. By cutting out the area to be cleaned, it is possible to intervene at the right place while preventing the robot from moving along the entire length of the roller. Contact between the robot and the cylinder is ensured only during cleaning. Such a cleaning system 20 allows for a faster response to any issues with the roller 17.

[0147] In practice, the response time to initiate the cleaning action is limited by the time required for the web 12 to travel along the distance between the roller to be cleaned and the sensor.

[0148] Therefore, the faster the web 12 moves, the sooner the cleaning operation can begin, the more quickly defects appear and anneal, resulting in better coating quality. The cleaning operation can be performed while the web 12 is being processed during coating or printing; there is no need to wait for each portion of the web 12 to be removed from the roller 17.

[0149] Additionally, this can result in energy savings due to significantly fewer robot movements, solvent savings, or reduced solvent pumping and dispensing.

[0150] Furthermore, mission cleaning mode is more precise and therefore more efficient because it cleans at a precise location, avoiding lateral movement, displacement, or expansion of the area to be cleaned, which would otherwise be caused by simultaneous pad movement and compression over a large area, potentially creating new defects or displacing or expanding existing defects.

[0151] The amount of solvent is adjusted to the exact required amount, specifically to avoid "fouling displacement" or secondary defects (excessive solvent), and also to reduce fumes from the solvent used for cleaning.

[0152] Furthermore, such a cleaning system 20 avoids unnecessary friction of the pads, which improves the safety of the facility and reduces the risk of fire in ATEX zones, as friction can actually cause sparks or heat.

[0153] Additionally, the cleaning system 20 provides precise solvent dosing during cleaning through automated dosing (as opposed to manual dosing), resulting in a healthier environment (air quality) and greater operator safety (no need to access coating areas involving high speed rotating machinery).

[0154] Additionally, the cleaning system 20 offers the advantage of controlled and improved cleaning responsiveness. The response time from defect detection to cleaning of the corresponding zone is limited to the time corresponding to the distance the film travels between the coating zone and the defect detection zone. The limiting factor for responsiveness is the scroll speed. The faster the film travels, the higher the responsiveness and the less loss or scrap occurs. The overall process yield is improved.

[0155] Furthermore, use of such a cleaning system 20 can reduce waste due to defects by 10%.

[0156] The proposed cleaning system is an automated, autonomous and compact system.

[0157] This cleaning system has the advantage of being limited in size, which is particularly interesting when inserted into narrow operating zones, and it also allows access to closed, secure, operator-inaccessible zones.

[0158] Furthermore, this cleaning system reduces intervention and maintenance, especially since it does not require the introduction of mobile tools or accessories into the zone.

[0159] In addition, the coating line can operate continuously and at high speeds 24 hours a day without interruption, limiting downtime and thereby optimizing production.

[0160] The cleaning system also provides the advantage of providing the robot with a route to remote locations for maintenance / service operations.

[0161] In particular, this cleaning system can be removed from the coating zone (operation zone), thereby eliminating the need for an operator to enter the coating zone and allowing, in particular, the replacement of used pads and the refilling of solvent tanks to be carried out in complete safety, which can be carried out in background time outside the operation zone.

[0162] This means that the cleaning system also results in an overall improvement in working conditions.

[0163] It should be understood that other embodiments and / or usage scenarios for such a cleaning system 20 may be contemplated. Specifically, the sensor 18 may be positioned after coating and before film formation, or after formation of the dried coated layer.

[0164] Additionally, the sensor 18 can be placed before the coating system to remove impurities before the coating operation. Additionally, the sensor 18 can be used in different ways.

[0165] For example, the sensor 18 and analysis unit 28 may also be used to track cleaning efficiency, track removal of defects or the occurrence of new defects, or track remaining defects.

[0166] A cartography of the coated film can be stored along with information about the localization and size of any defects that were created and not removed, which can be used to monitor quality indicators.

[0167] Cartography can be used to verify the effectiveness of the cleaning system 20 and compare the presence of residual defects before and after the start of a robotic mission.

[0168] The cleaning system 20 may be the cleaning system described in document US Pat. No. 10,040,101 or the cleaning system disclosed in document US Pat. No. 1,192,149.

[0169] Additionally, it may be noted that cleaning system 20 is also capable of cleaning other types of rollers, such as backing rolls, transfer rolls, gravure rolls, metering rolls, idler rolls, dryer rolls, embossing rolls, etc.

[0170] Therefore, the cleaning system 20 is compatible with all types of rollers used in web handling thin film processes.

[0171] In particular, the cleaning system 20 may also be used to clean any conveyor or drive rollers.

[0172] Furthermore, the rollers may actually be conveyor belts carried by roller assemblies.

[0173] In that sense, the element has infinite curvature and therefore forms a substantially planar surface.

[0174] Thus, more generally, cleaning system 20 is configured to clean the exterior surfaces of any moving elements of coating equipment 5. Preferably, cleaning system 20 is implemented in coating equipment that experiences high levels of fouling, such as for wet coating, printing, or laminating.

[0175] The cleaning system 20 may be used with any number of rollers, particularly three-roller or five-roller systems, and is adapted for any type of roller material (e.g., EPDM, steel, HNBR, tungsten, or chrome-plated steel, etc.).

[0176] Similarly, the cleaning system 20 may be used in other coating / printing / molding techniques.

[0177] Different versions of both coating and printing are used. Furthermore, these techniques may be related to the surface finish. These techniques can be classified by the number of rollers, the direction of rotation of the rollers, and the roller design.

[0178] For example, one common technique is the three-roller system (fountain roller color deck). A conventional three-roller printing deck is mounted on a pair of frames or consoles and typically consists of a pair of angular contact ball bearing blocks that receive the plate cylinders and a pair of ink roller bearing blocks to house the ink rollers (anilox roller and fountain roller). A structure for receiving the ink fountain is typically incorporated.

[0179] Additionally, the cleaning system 20 may be used in roll coating or roll-free coating.

[0180] In roll coating and related processes, the wet coverage is determined by the flow rate of the coating composition and the coating speed. Roll coating is a coating method that controls both the thickness and uniformity of the coated film by fluid flow in the nip or gap between a pair of rotating rolls. This extends from considering a zero-speed roll covering a knife and blade to an infinite-radius coating roll covering a flat sheet.

[0181] Gravure coating is capable of covering the web with a coating layer as thin as a few micrometers, typically about 3 μm.

[0182] When coating a thin layer of pigmented black ink, defects on the coated layer are caused by fouling within the coating machine. That is, the backup roller is soiled with ink, for example, from the coating element or ink reservoir. Roll fouling can be caused by ink splashes, ink in droplet form (due to aerodynamic effects, component volatility, etc.), mist, leakage, etc. Typically, ink droplets "fly" from the doctor blade chamber, reservoir, or application roller onto the backup roll (material protrusions).

[0183] The ink then dries more or less quickly depending on the ink composition, pigment, and solvent used. If there is too much dried solid ink on the backup roll, it can create an undesirable localized increase in thickness, which can displace the actual coating composition that is to be applied to the web. This results in defects on the coated web, such as white spots, blank spaces, or voids, where the coating composition is missing. These are sometimes called "sleeve defects" because they result from sleeve fouling.

[0184] Using conventional cleaning techniques (robots) may result in new defects appearing when attempting to clean the sleeve, and in fact the fouled area may expand or shift as, for example, dried ink spreads over the sleeve.

[0185] Furthermore, the thinner the web being coated, the more significant the impact of fouling on the quality of the coated web.

[0186] The cleaning system 20 allows for efficient cleaning of the sleeve by real-time detection and recognition of the appearance of sleeve defects on the coated web 12 .

[0187] It may be possible to detect fouling directly on the sleeve.

[0188] However, if the sensor 18 is aimed at the roller surface, proper detection cannot be achieved during the coating of dark coating compositions. Depending on the type of backup roll used, the contrast between the sleeve appearance and the fouled area is often too low (black ink on a black cover), or the gloss of the anilox roller can prevent detection of the fouling.

[0189] Furthermore, the rotation of the roller makes it more difficult to find the fouled area to clean. For this reason, methods developed for cleaning sleeves remove the fouling on the sleeve by first controlling the coated layer of the web and then initiating the cleaning action.

[0190] By using the cleaning system 20, cleaning occurs without adding new defects. The cleaning system 20 can be activated when defects appear, are detected, and are recognized. Thus, the cleaning system 20 operates as a corrective defect handling system. Furthermore, the cleaning system 20 can selectively clean specific areas to be cleaned according to analysis unit commands. The cleaning operation is precise and on-demand, starting and stopping in response to the occurrence and removal of defects.

[0191] Additionally, the cleaning system 20 may move in three degrees of freedom relative to the surface being cleaned to compensate for the curvature of the roller and its velocity. The path of the cleaning device may be sinusoidal, elliptical, circular, linear, etc.

[0192] Additionally, forward roll coating may benefit from the cleaning system 20 .

[0193] With such a technique, the web travels over a backup roll while the application roller rotates in the same direction as the backup roller, at the same or a different speed. The coating composition can be delivered by a slot die.

[0194] In another design, a fountain roll can remove liquid from the pan and transfer it to the applicator roll, creating a three-roll pan delivery system. A third roll can be added to impinge on the applicator roll, and liquid can be delivered to the nip between the third roll and the applicator roll. Any number of rolls can be used, and the rolls can be smooth, chrome-plated steel, or rubber-coated. Additionally, ceramic rolls can be used.

[0195] In the case of screen printing, as shown diagrammatically in FIG. 5, particularly in rotary screen printing, the screen is a seamless perforated nickel cylinder, and the perforation rate is expressed by a mesh number indicating the number of holes per linear inch. A squeegee is attached inside the perforated roller to supply and distribute the coating composition (paste). The squeegee blade forces the paste through the perforated screen. A whisper blade can smooth the applied coating layer. Related coating techniques include pattern-type coating, dot coating, plain paste coating, or foam coating. In rotary screen printing, a cleaning system is configured to clean the outer surface of the roller that carries the web.

[0196] Flexography techniques (more often called flexographic printing) can be considered in coating equipment, and such techniques are shown diagrammatically in Figure 6.

[0197] Such printing techniques are high-quality printing techniques for the packaging sector (compared to letterpress, gravure, and offset printing). The web to be printed can be, for example, packaging material such as paper, plastic film, aluminum foil, etc. Flexographic printing is useful due to its high flexibility and high-quality printing on a variety of materials, as well as its wide and variable speed range. In flexography, the web can be printed with a pattern defined by an intermediate roller. The cleaning area is located on the outer surface of a counter roller, which forms a nip with the intermediate roller. During coating using an engraved roller (Figure 7) or a micro roller (Figure 8), a pick-up roll transfers the coating composition from a reservoir to the web. In both coating techniques, increasing the coating speed also increases the tendency to smear nearby rollers and therefore affect the surface of the coated web.

[0198] Additionally, the cleaning system 20 may be used in kiss coating.

[0199] In kiss coating, the web, which is moving in the same direction as or against the applicator roll, may be held against the applicator roll solely by web tension. The roller to be cleaned may be part of a roller assembly used to transport the web.

[0200] Additionally, the cleaning system 20 may be used in reverse roll coating.

[0201] In reverse roll coating, the web is conveyed in the opposite direction from the application roll. A backup roll, sometimes called a "sleeve," is usually rubber-coated, and the web travels between the backup roll and the application roller, which press against each other to meter the amount of coating composition and thus control the thickness or basis weight of the coating composition applied to the web. The amount of liquid transferred to the web may be controlled by the application roll, which is a counter-rotating metering roll.

[0202] Several different reverse roll configurations are possible. In many cases, a doctor blade is used to wipe excess coating onto the applicator roll in the doctor blade chamber. This technique allows for the metering of liquid coating composition onto the applicator roll immediately after delivery of the coating composition from a reservoir onto the roll.

[0203] Additionally, cleaning systems may be implemented for dip coating, where the web is immersed in a liquid. Excess coating is removed from the web using a pair of squeeze rollers. Splashes caused by the introduction and exit of the web into and from the coating composition are a major source of defects due to fouling of nearby rollers.

[0204] Additionally, the cleaning system 20 may be used in hot melt coatings.

[0205] Other techniques that may benefit from the cleaning system 20 include rod coating, wire wound rod coating (Mayer rod), doctoring to remove excess coating liquid, knife coating, blade coating, air knife coating, dip coating, etc.

[0206] In either case, the cleaning system 20 allows for increased efficiency of the coating machine.

[0207] This is advantageous in many applications, namely flexible thin films (such as printed packaging), food containers, paper, textiles, technical coatings, prepregs, adhesive tapes, artificial leather manufacturing, batteries (electrode plates or primers on conductive surfaces), and monochrome printing presses (screen printing).

[0208] In certain technical fields, coated thin webs are used for thermal transfer printing, where the coated web is cut into narrow ribbons. High quality ink ribbons are essential for high-speed printing, performance-demanding end uses, and / or high-durability printers. Therefore, the quality of the coated thin web has a direct impact on print quality (print sensitivity, density, etc.). Such ribbons are often used to print labels, tags, etc.

[0209] Additionally, cleaning system 20 may be used in the printing industry and within printers (electrophotographic, laser printing, thermal transfer printers, etc.).

[0210] Additionally, cleaning system 20 may be used in plastic sheet manufacturing, i.e., the composition is extruded alone, or plastic sheets may be manufactured by coating onto a substrate and then removed from the substrate after solidification (peeling).

[0211] Additionally, such a cleaning system 20 may also be used on non-flexible webs that are to be coated / printed, such as in the manufacture of rigid floor coverings.

[0212] Additionally, cleaning system 20 can be particularly useful in high value-added products, i.e., demanding end uses requiring zero defect products.

[0213] Indeed, by constraining the number / size of defects and cartographically representing the remaining defects, the end user is able to recognize the location of the defects and / or discard zones containing the remaining defects.

[0214] Additionally, applying a glue or adhesive by any technique, such as wet coating or dry lamination, may be beneficial, for example, during lamination of two surfaces using a liquid or pressure-sensitive adhesive. [Explanation of symbols]

[0215] 5 Coating equipment 6 Unwinder 7 Rewinder 8 Dryer 9 Hardening machine 10 Coating Machine 12. Web 13 Ink reservoir 14 Coating Elements 15 Coating layer 16 Coating roller 17 Counter roller 18 Sensors 20 Cleaning System 22 Exterior 24 Robot Arm 26 Cleaning Devices 28 Analysis Units 30 Command Units 32 Grip 34 Cleaning Pads 36 Exterior 38 Solvent Reservoir 40 Pressure Unit

Claims

1. A cleaning system (20) configured to clean an outer surface (22) of a moving element (17) of a coating installation (5), the coating installation (5) comprising a coating machine (10) configured to coat and / or print and / or form a layer on a web (12), the cleaning system (20) comprising: a robotic arm (24) equipped with a gripper (32); a cleaning device (26) mounted on the gripper (32), the cleaning device (26) being configured to clean the outer surface (22) of the movable element (17); a command unit (30) configured to command the robot arm (24) and the cleaning device (26) to perform a cleaning task on a portion of the outer surface (22) of the mobile element (17); Equipped with The cleaning system (20) is configured such that the command unit (30) receives at least one defect characteristic and initiates a cleaning task according to each received defect characteristic, the defect characteristic being a characteristic of at least one defect in the layer.

2. The cleaning system (20) comprises: - receiving data from a sensor (18), said data being an image of said layer coated and / or printed by said coating machine (10); - analyzing the data to detect at least one defect characteristic of at least one defect in the layer; an analysis unit (28) configured to perform Further provided with 10. The cleaning system of claim 1.

3. 2. The cleaning system of claim 1, wherein the cleaning device (26) comprises an interface unit configured to receive information regarding at least one defect in the layer from a user, and the command unit (30) is configured to command the robot arm (24) and the cleaning device (26) according to the information regarding the at least one defect in the layer.

4. 3. The cleaning system of claim 2, wherein the at least one defect characteristic detected by the analysis unit (28) is whether or not a defect is present.

5. The cleaning system of claim 1 , wherein each defect is associated with a defect severity, and one of the defect characteristics is the defect severity.

6. 6. The cleaning system of claim 5, wherein the command unit (30) is configured to initiate a cleaning task if the defect severity of the detected defect exceeds a predetermined defect severity.

7. 2. The cleaning system of claim 1, wherein each defect in the layer belongs to a predetermined defect group, a defect characteristic is the defect group to which the defect belongs, and an area characteristic of the area to be cleaned by the cleaning device (26) is selected according to the defect characteristic.

8. 8. The cleaning system of claim 7, wherein one area characteristic is the surface of the area to be cleaned.

9. 9. The cleaning system of claim 8, wherein one area characteristic is identification of a center of the area to be cleaned.

10. 10. The cleaning system according to claim 9, wherein the identification of the center of the area to be cleaned is selected from among three zones: a left portion of the movable element (17), a central portion of the movable element (17), and a right portion of the movable element (17).

11. 2. The cleaning system of claim 1, wherein the cleaning task is characterized by cleaning parameters, and the command unit (30) is configured to calculate each cleaning parameter depending on the defect characteristics.

12. 2. The cleaning system of claim 1, wherein the cleaning device (26) comprises a cleaning pad configured to contact the portion of the outer surface (22) of the movable element (17).

13. 2. The cleaning system of claim 1, wherein the cleaning pad has an outer surface (22) with foam, in particular melamine foam.

14. 10. The cleaning system of claim 1, wherein the cleaning device further comprises a cleaning pad, a solvent reservoir, and a pressure unit, the pressure unit configured to deliver the solvent from the solvent reservoir to the cleaning pad.

15. 2. The cleaning system according to claim 1, wherein the movable element of the coating installation (5) is a roller (17).

16. A coating machine (10) equipped with a cleaning system (20) according to any one of claims 1 to 15.

17. A coating installation (5) comprising a cleaning system (20) according to any one of claims 1 to 15.

18. 1. A method for cleaning the outer surfaces (22) of moving elements of a coating installation (5), said coating installation (5) comprising a coating machine (10) configured to coat and / or print and / or form a layer on a web (12), said method comprising: a robotic arm (24) equipped with a gripper (32); a cleaning device (26) mounted on the gripper (32), the cleaning device (26) being configured to clean the outer surface (22) of the movable element (17); a command unit (30) configured to command the robot arm (24) and the cleaning device (26) to perform a cleaning task on a portion of the outer surface (22) of the mobile element (17); The cleaning system (20) is implemented by The method comprises: - receiving at least one defect characteristic, the defect characteristic being a characteristic of at least one defect in the layer; - initiating a cleaning task according to each received defect characteristic; A method comprising:

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