Application device and method

Abstract

Application device and method for applying a coating medium on a moving surface, comprising an application head which extends over the entire width of the moving surface, wherein a linear guide is also provided, which extends in the width direction of the application device, in particular parallel to the application head, and which is provided in order to attach one or more cleaning elements for the application head.

Description

[0001] Application device and method

[0002] The invention relates to an application device for applying a coating medium to a moving surface according to the preamble of claim 1 and to a method for cleaning an application head.

[0003] During the production or processing of fibrous webs such as paper or board webs, a coating medium is often applied to these webs in order to influence, for example, the surface properties, the permeability or the strength properties of the fibrous web.

[0004] The coating medium can then either be applied directly to the moving paper web or first applied to a moving transfer surface (e.g. a transfer roller) and from there transferred to the paper web.

[0005] There are a variety of options for the design of the application head from which the coating medium is dispensed.

[0006] For example, an application head is known from DE 10 2016 209 336 A1 and DE 103 59 120 A1, in which the coating medium is discharged from a slot nozzle in the form of a freely falling curtain onto a paper web or an application roller.

[0007] The documents DE 20 2017 100 655 U1 and DE 20 2015 009 603 U1 show application heads in which the coating medium is applied to a moving surface by means of spray nozzles.

[0008] The applicant's subsequently published patent application DE102022105510 shows an application head that has both a slot nozzle and an air nozzle. During operation of these application heads, the application heads may become contaminated by the coating medium itself or other contaminants. For example, individual spray nozzles or individual spots or regions of the slot nozzles may become clogged, impairing the application of the coating medium. Therefore, repeated maintenance and cleaning of these application heads are essential.

[0009] DE 103 59 120 A1 proposes to provide a closable opening for cleaning curtain nozzles on the front side of the nozzle.

[0010] From DE 20 2015 009 603 U1 it is also known to provide a second spray application device with a plurality of spray nozzles during a spray application, so that one set of nozzles is always in the application position and the second set of nozzles is in the maintenance or cleaning position.

[0011] The actual cleaning of these application heads, however, is always done manually using a sponge, hose, and high-pressure cleaner. This is difficult and time-consuming, and particularly ineffective or only partially effective in the narrow nozzle gap when the application head is installed in the machine.

[0012] With the spray nozzles, the second set of nozzles usually has to be removed from the machine to ensure thorough cleaning without interrupting the machine's operation for too long.

[0013] The object of the invention is to enable improved cleaning of the application head and trouble-free operation of the application device.

[0014] Furthermore, it is an object of the invention to propose a flexible system that can be used for different types of application heads.

[0015] The object is achieved according to the invention by an application device according to claim 1 and a method for cleaning an application head according to claim 12. Further advantageous embodiments of the present invention can be found in the subclaims.

[0016] Proposed is an application device for applying a coating medium to a moving surface, comprising an application head extending across the entire width of the moving surface. According to the invention, a linear guide is also provided, which extends in the width direction of the application device and is intended for attaching one or more cleaning elements for the application head.

[0017] The moving surface can be a material web, in particular a paper, cardboard, or pulp web. Alternatively, the moving surface can also be a transfer surface, for example, the surface of a transfer roller. From this transfer surface, the coating medium can be transferred to a material web in a transfer nip.

[0018] The feature that the application head extends across the entire width of the moving surface is to be considered fulfilled if the application head extends at least across that part of the surface which is intended for coating. For example, in indirect application the transfer roller can be somewhat wider than the material web to be coated later. In this case an application head can also extend only across the width of the later material web. However, since these differences are on the order of a few centimeters, which are hardly significant compared to the usual widths of paper machines of around 10m and more, these linguistic distinctions are omitted in this application for the sake of ease of readability and the term "entire width" is used instead. The coating media can be, for example, a starch solution, a pigment-containing coating color or a barrier medium.

[0019] Preferably, the linear guide can be provided on the application head. This can be done either by attaching the linear guide to the application head. Alternatively, the application head itself can be designed to serve directly as a linear guide. If the linear guide cannot or should not be attached directly to the application head, an equivalent solution is for the linear guide and the application head to be held by the same support device.

[0020] In preferred embodiments, it can be provided that the application device comprises at least one cleaning element which is attached to the linear guide and is in particular detachably attached.

[0021] Cleaning the application heads in the machine, e.g. a paper machine, is difficult for various reasons.

[0022] For one thing, these systems are very wide. Widths of 10 meters and more are common today. This makes the areas of the application head, which are located in the center of the web, particularly difficult to reach.

[0023] Furthermore, the available installation space is very limited. This applies both to direct application, where the application head must be positioned close to the paper web, and to indirect application, where the transfer roller(s) take up a lot of space.

[0024] In addition, the components and structures to be cleaned are relatively small, so that precise positioning of cleaning elements is necessary.

[0025] The present invention solves these problems by providing a linear guide within the application device. Like the application head, this guide extends in the width direction of the moving surface. In advantageous embodiments, the linear guide can be provided to extend parallel to the application head. This guide can be constructed relatively compactly, so that it can be inserted into the available installation space. A suitable cleaning element can be attached to this linear guide. If the cleaning element is detachably attached, the cleaning element can only be inserted into the machine at the time of cleaning and removed again after cleaning is complete.

[0026] It is particularly advantageous if the linear guide is arranged on the application head itself, as described above. This offers several advantages.

[0027] On the one hand, such a linear guide is easy to implement and can also be easily retrofitted into existing systems.

[0028] Furthermore, attaching the linear guide to the application head using simple means ensures that the relative position of the linear guide to the application head to be cleaned can be maintained very precisely.

[0029] In addition, the weight of the cleaning element is comparatively low, so that any influence on the positioning of the application head by a traversing cleaning element can be excluded.

[0030] For example, an average cleaning element—including the drive—will weigh between 10 kg and 20 kg. Since a machine-wide application head often weighs over 100 kg / m, and the supporting structures and traverses are designed to hold this weight in place, the additional weight of the cleaning element is negligible.

[0031] This design also eliminates the need for a separate traverse or bracket for the linear guide. This allows the application device to be implemented very cost-effectively.

[0032] If the linear guide cannot or should not be attached directly to the application head, an equivalent solution is that the linear guide and the application head are held by the same support device.

[0033] Multiple cleaning elements can also be provided. In particular, it can be advantageous to provide different types of cleaning elements that operate at different locations or with different cleaning methods. This modular design allows application devices according to aspects of the invention to be used very flexibly.

[0034] In preferred embodiments, the at least one cleaning element can be movable along the linear guide. This makes it possible to clean the entire width of the application head with a single, relatively compact cleaning element. Furthermore, the installation of a small, movable cleaning element is significantly easier than the installation of a rigid cleaning element that covers the entire width of the machine.

[0035] The cleaning element can be moved manually, by motor, pneumatically, or hydraulically. Manual movement is very simple and inexpensive, for example, using a cable pull. For simple cleaning elements, such as a sponge or similar device that is pulled directly over the area to be cleaned, e.g., over the application head, this may be sufficient. For more complex and heavier cleaning elements, such as cleaning elements with cleaning nozzles, an automatic or semi-automatic process is preferable.

[0036] The linear guide itself can be provided with the means for moving the cleaning element. The cleaning element is then attached to the movable unit. This allows the cleaning element to be kept very simple. This can be particularly advantageous for mechanical cleaning elements (e.g., sponges, foil, etc.). Furthermore, only one moving unit is required, even if several different cleaning elements are used.

[0037] Alternatively, the linear guide can be designed very simply, for example, consisting only of a bar, rail, or similar. In this case, the means for movement can be integrated into the cleaning element. This has the advantage that the linear guide can be designed very simply and compactly.

[0038] In addition, the components of the traversing unit are only installed in the machine during the cleaning process, thus preventing contamination of the traversing unit during operation of the application device. This solution can be particularly advantageous for more complex cleaning units that include, for example, spray nozzles, etc.

[0039] It can be provided that the application head has a slot nozzle, wherein the slot extends in particular over the entire width direction of the cleaning device.

[0040] In particular, when applying a curtain or using the combined slot and air nozzle of DE102022105510, the slot width of the slot nozzle is usually less than 2 mm, especially less than 1 mm.

[0041] Alternatively or additionally, it can be provided that the application head has one or more spray nozzles, wherein the plurality of spray nozzles are arranged in particular along the width direction of the application device.

[0042] In advantageous embodiments, it can be provided that the cleaning element has means for mechanical cleaning, in particular a cleaning film, a brush or a sponge.

[0043] A sponge can be used to clean the surface of a discharge head in particular.

[0044] The surface of the application head can also be cleaned with a brush. A rotating brush can increase the cleaning effect.

[0045] A cleaning film can be particularly advantageous for slot nozzles. Since the gap width of these wide slot nozzles is very small, the risk of contamination is relatively high. For cleaning, a cleaning film can be inserted into the nozzle gap, for example, on the driver's side, and then moved along the width direction.

[0046] The cleaning films can be made of plastic, metal, CFRP, GRP, or other suitable materials. Since gap widths of < 1 mm regularly occur, these cleaning films must be very thin yet offer resistance. Therefore, CFRP and GRP films are particularly recommended. Such CFRP or GRP films, like metal films, are quite dimensionally stable compared to thin polymer films made of PVC or similar materials, making them easier to insert into the gap to be cleaned. Such dimensionally stable films can also be referred to as "platelets." For the sake of clarity, the term "film" is intended to encompass such plates in this application.

[0047] While the cleaning film itself is a wear part, the majority of the cleaning element, including the film holder or the moving device, is reusable. The cleaning tool holder for quickly replaceable cleaning films, for example, can consist of a clamp.

[0048] Alternatively or additionally, the cleaning element may be provided with one or more cleaning nozzles. In particular, it may be advantageous to provide two or three cleaning nozzles, preferably adjacent to one another.

[0049] These cleaning nozzles can be supplied with a cleaning fluid such as air, water, etc., which can optionally be supplemented with surfactants or other cleaning agents.

[0050] Depending on the setting and pressure, the cleaning fluid can also penetrate into the interior of the application head or, for example, remove dirt from inside the spray nozzles.

[0051] By moving individual cleaning nozzles along the linear guide, the entire width of the application head can be cleaned without having to install the cleaning medium lines in the installation space. After cleaning, these lines, like the rest of the cleaning element, can be removed from the application device.

[0052] It can be provided that both the application head and the linear guide are permanently installed. Alternatively, it can be provided that the application head can be moved, in particular pivoted, from a working position to a maintenance position. This means that cleaning can be carried out in a more favorable position and, if necessary, parts of the application head can be reached which would be impossible or difficult to reach in the working position - e.g. due to insufficient distance to the transfer roller. This can be realized, for example, as in DE 20 2015 009 603 U1, whereby a second spray application device with a plurality of spray nozzles is provided for a spray application, so that one set of nozzles is always in the application position and the second set of nozzles is in the maintenance or cleaning position. However, other implementations are also possible.

[0053] Alternatively or additionally, it can also be provided that the linear guide can be moved, in particular pivoted, from a parking position to a maintenance position. The parking position can, for example, be selected such that the linear guide has as little impact on the production process as possible.

[0054] In preferred embodiments, it can be provided that the cleaning element has an active and a passive state, and that means are provided to switch the cleaning element from the active to the passive and / or from the passive to the active state.

[0055] One implementation of this feature could be that a mechanical cleaning element, such as a sponge, has no contact with the surface to be cleaned in its passive state. In its active state, it is then pressed against the surface to be cleaned, particularly by pivoting it.

[0056] An alternative implementation of this feature could be that a cleaning nozzle is not switched on in the passive state. By supplying a cleaning fluid, the nozzle is then switched to the active state.

[0057] Depending on the cleaning element, other designs are also conceivable.

[0058] This design has the advantage that the movement and positioning of the cleaning element can be carried out independently of the cleaning process. This allows for targeted cleaning of individual areas across the width. This reduces wear on the cleaning element and the consumption of cleaning agents.

[0059] For this purpose, it can be advantageous to provide a sensor downstream of the application device in the process direction, e.g., a high-resolution scanner, particularly with web inspection systems, which can determine the position of a defect in the event of a fault, such as an uncovered stripe in the fiber web. The cleaning element can then be moved precisely to this area—preferably in a passive state—and specifically eliminate the defect.

[0060] Furthermore, a method for cleaning an application head is proposed, wherein the application head is provided in an application device according to one aspect of the invention, and wherein the method comprises the steps: a) attaching at least one cleaning element to the linear guide; b) moving the cleaning element in the width direction of the application head along the linear guide.

[0061] The cleaning element can be in the active state while moving along the linear guide. Thus, the application head is cleaned throughout the entire movement process.

[0062] Alternatively, it can also be provided that the cleaning element is moved in the passive state to a first position, where it is switched from the passive state to the active state. The cleaning element can then clean specifically at this location. Subsequently, the cleaning element can be moved, in particular, to a second position.

[0063] It can be advantageous if, in the web travel direction, sensors are provided downstream of the application device to detect a defect in the fibrous web, and the first position is determined based on these sensor values. For example, a high-resolution scanner can be provided, particularly as part of a web inspection system, which detects a defect such as an uncovered stripe in the fibrous web and determines its position (as the first position). The cleaning element can then be moved—preferably in a passive state—to this first position and specifically clean the application head at this point.

[0064] A variety of sensors can be suitable as sensing devices. These could be scanners that measure the basis weight, for example. Alternatively, they could be gloss sensors that measure the gloss of the paper surface.

[0065] Camera-based optical systems are also often used.

[0066] However, it is also possible to determine the location of the contamination by looking for individual thickened or thinned stripes on the roll-up.

[0067] This list of possible sensor means can be expanded.

[0068] The invention is explained below with reference to figures. The invention is not limited to these embodiments. The figures show in detail:

[0069] Figure 1 shows an application device according to one aspect of the invention

[0070] Figure 2 shows an application device according to a further aspect of the invention. Figures 3a and 3b show application devices according to further aspects of the invention.

[0071] Figure 4 shows an application device known from the prior art.

[0072] Figure 5 again shows an application device according to an aspect of the invention Figure 6 shows a film press according to an aspect of the present invention

[0073] Figure 1 shows a side view of an application device according to one aspect of the present invention. The application head 1 is designed here as a slot nozzle of a curtain application unit, which extends—into the plane of the sheet—across the entire width of the running surface 10. The application head 1 is connected to the frame of the machine via a bracket (not shown). Furthermore, a linear guide 2 is provided, which also extends in the width direction. In the embodiment shown here, the linear guide 2 is attached directly to the application head 1 and runs parallel to it.

[0074] REVISED SHEET (RULE 91) ISA / EP Figure 1 also shows a cleaning element 3 for cleaning the application head 1. Here, cleaning is performed mechanically via a cleaning film 4a, which is inserted into the nozzle gap of the application head 1. When the cleaning element 3 is moved along the linear guide 2, the cleaning film 4a is pulled through the nozzle gap and can thus remove contaminants from the gap. Since gap widths of < 1 mm regularly occur, these cleaning films 4a should be very thin while still offering resistance. Therefore, relatively dimensionally stable CFRP and GRP films are particularly recommended.

[0075] A holder 5 is also provided. This holder 5 can be part of the cleaning element 3 and can be easily removed and installed with it. Alternatively, this holder 5 can also be separated from the cleaning element 3, so that only the holder for the cleaning film 4a is removed from the machine—e.g., to change the cleaning film 4a—while the holder 5 remains permanently in the machine.

[0076] The cleaning element 3 can be moved along the linear guide in various ways. One possibility is manual movement using a cable pull or a crank. However, this is only practical for narrower machines. Typically, the movement is performed by motor, pneumatically, or hydraulically. The means for moving the cleaning device can be installed either in the linear guide. Alternatively, the means for movement—e.g., a drive motor—can be installed in the cleaning element 3 itself or in the holder 5.

[0077] The embodiment shown in Figure 2 differs from that in Figure 1 in that, instead of mechanical cleaning using a cleaning film 4a, one or more cleaning nozzles 4b are provided. In particular, it may be advantageous to provide two cleaning nozzles 4b next to each other. It is also possible to use both cleaning films 4a and cleaning nozzles 4b together in one cleaning element 3.

[0078] The embodiment of Figure 2 is particularly advantageous when the application head 1 is equipped with a spray nozzle instead of a slotted nozzle 1a. Figures 3a and 3b show further application devices according to aspects of the invention. As known from DE 20 2015 009 603 U1, the application head 1 is equipped with two sets of spray nozzles 1b for applying the coating medium to a moving surface 10. While one set of spray nozzles 1b is in the working position 6a, the second set of spray nozzles 1b is in a maintenance or cleaning position 6b.

[0079] Here, too, a linear guide 2 is provided, extending in the width direction of the application device. The linear guide 2 is attached to the application head 1, or the application head 1 and the linear guide 2 are held by the same support device—holder 5.

[0080] Furthermore, a cleaning element 3 is provided, which is attached to the linear guide 2 and, in particular, is detachably attached. The linear guide 2 and the cleaning element 3 are mounted such that the spray nozzles 1b can be cleaned in the cleaning position 6b, while the application device can continue to operate with the remaining spray nozzles in the working position 6a.

[0081] In the device shown in Figure 3a, a cleaning sponge 4c is provided for cleaning. This can be advantageous because, unlike cleaning with cleaning nozzles 4b, it does not produce any spray mist, which could impair the ongoing operation of the application device.

[0082] A variant of this device is shown in Figure 3b. In contrast to Figure 3a, the cleaning element 3 comprises both a cleaning sponge 4c and a cleaning nozzle 4b. In this case, it can be provided that both the cleaning nozzle 4b and the cleaning sponge 4c are active while the cleaning element is moved along the linear guide. However, it can also be provided that the cleaning nozzle 4b and / or the cleaning sponge 4c are in a passive state until the cleaning element 3 has moved to a first position. This can, for example, be a heavily soiled spray nozzle 1b. A switch can then take place from the passive to the active state, so that in particular the cleaning nozzle 4b is activated by supplying cleaning fluid and specifically cleans the soiled spray nozzle 1b or the soiled part of the application head 1.

[0083] CORRECTED SHEET (RULE 91) ISA / EP It is advantageous if a suitable sensor is provided downstream of the application unit in the process direction, which can detect the position of the contamination via resulting disturbances in the paper web and can transmit this to a control system of the cleaning element 3.

[0084] Figure 4 shows an application device as known from the prior art, in particular from DE102022105510. The application head 1 comprises both a slot nozzle 1a, from which the coating medium is dispensed, and a spray nozzle 1b. This spray nozzle 1b is pressurized with air, so that the coating medium dispensed from the slot nozzle 1a across the entire width of the machine is deposited onto the moving surface 10 in the form of a spray mist.

[0085] With this application head 1, both the slot nozzle 1a and the spray nozzle 1b can become contaminated. Simple and reliable cleaning of the nozzles 1a and 1b is therefore particularly advantageous.

[0086] Figure 5 shows a further development of the device from Figure 4 according to one aspect of the invention. Here, a linear guide 2 is again provided for receiving a cleaning element 3. Since the distance between the air nozzle 1b and the moving surface 10 is usually very short, designs in which the linear guide 2 and / or the spray nozzle 1b and / or the slot nozzle 1a can be moved, in particular pivoted, into a maintenance or cleaning position are often particularly advantageous.

[0087] In the embodiment shown in Figure 5, the cleaning element 3 has both a cleaning film 4a for cleaning the slot nozzle 1a and a cleaning nozzle 4b for cleaning the spray nozzle 1b. Various other embodiments are also conceivable here. For example, a cleaning nozzle 4b can also be provided for cleaning the slot nozzle 1a. For example, a single cleaning nozzle 4b can also be provided, the spray direction of which is or can be adjusted so that it can be used to clean both the spray nozzle 1b and the slot nozzle 1a. Figure 6 shows a size press for applying a starch solution to both sides of a fibrous web. Two transfer rollers 20 are provided, which are arranged such that they form a transfer nip 25 in which the starch solution is transferred from the surface of the transfer rollers 10, 20 to a paper or cardboard web.An application head 1 is provided on each of the transfer rollers, which, analogous to Figure 4, has a slot nozzle 1a and a spray nozzle 1b. Alternatively, a pure slot nozzle 1a or a pure spray nozzle 1b could also be provided.

[0088] To ensure good penetration of the starch solution into the fibrous web, it may be advantageous if both transfer rollers 20 are provided with a hard surface. The hardness of the roller surface can be, in particular, greater than 50 ShoreD or even greater than 60 ShoreD.

[0089] A linear guide 2 is provided for each application head 1 in the film press. It is particularly advantageous if the two linear guides 2 are designed identically. This makes it possible, for example, to clean both application heads 1 with a single cleaning element 3. This is particularly advantageous if the cleaning element 3 is very complex and, for example, includes its own drive and / or devices for supplying cleaning nozzles 4b with cleaning fluid.

[0090] In the embodiment shown in Figure 6, the linear guide 2 is attached to the spray nozzle 1b or both share a common holder 5. Alternatively or additionally, it can also be provided, for example, that the linear guide 2 is provided on the slot nozzle 1a.

[0091] Depending on the application, it may also be advantageous to provide a linear guide 2 on both the spray nozzle 1b and the slot nozzle 1a. Thus, a cleaning element 3 could be provided for each slot nozzle 1a and the spray nozzle 1b, which can independently clean the respective part of the application head 1. List of reference symbols

[0092] 1 application head

[0093] 1a Slot nozzle 1 b Spray nozzle

[0094] 2 linear guide

[0095] 3 Cleaning element

[0096] 4a Cleaning film

[0097] 4b Cleaning nozzle 4c Cleaning sponge

[0098] 5 Bracket

[0099] 6a Working position

[0100] 6b Cleaning position

[0101] 10 running surface 20 transfer roller

[0102] 25 transmission nip

Claims

Patent claims 1 . Application device for applying a coating medium to a moving surface, comprising an application head which extends over the entire width of the moving surface, characterized in that a linear guide is also provided which extends in the width direction of the application device, in particular parallel to the application head, and which is provided for attaching one or more cleaning elements for the application head.

2. Application device according to claim 1, characterized in that the linear guide is provided on the application head or the linear guide and the application head are held by the same support device.

3. Application device according to one of the preceding claims, characterized in that the application device comprises at least one cleaning element which is attached to the linear guide and is in particular detachably attached.

4. Application device according to claim 3, characterized in that the at least one cleaning element is designed to be movable along the linear guide, wherein the method can be carried out in particular manually, motorically, pneumatically or hydraulically.

5. Application device according to one of the preceding claims, characterized in that the cleaning element has means for mechanical cleaning, in particular a cleaning film - preferably in the form of a CFRP or GFRP film -, a sponge or a brush.

6. Application device according to one of the preceding claims, characterized in that the cleaning element has one or more cleaning nozzles.

7. Application device according to one of the preceding claims, characterized in that the application head has a slot nozzle, wherein the slot extends in particular over the entire width direction of the cleaning device, wherein the slot width of the slot nozzle is preferably less than 2 mm, particularly preferably less than 1 mm.

8. Application device according to one of the preceding claims, characterized in that the application head has one or more spray nozzles, wherein the plurality of spray nozzles are arranged in particular along the width direction of the application device.

9. Application device according to one of the preceding claims, characterized in that the application head can be moved, in particular pivoted, from a working position to a maintenance position and / or the linear guide can be moved, in particular pivoted, from a parking position to a maintenance position.

10. Application device according to one of the preceding claims, characterized in that the cleaning element has an active and a passive state, and that means are provided for switching the cleaning element from the active to the passive and / or from the passive to the active state.

11. Application device according to one of the preceding claims, characterized in that the application device has a first application head, to which a first linear guide is assigned, and a second application head, to which a second linear guide is assigned, and wherein the application device further has a cleaning element which can be attached alternately to the first linear guide and to the second linear guide.

12. A method for cleaning an application head, wherein the application head is provided in an application device according to one of the preceding claims, and wherein the method comprises the steps of: a) attaching at least one cleaning element to the linear guide; b) moving the cleaning element in the width direction of the application head along the linear guide.

13. Method according to claim 12, characterized in that the cleaning element is in the active state during movement along the linear guide.

14. The method according to claim 12, characterized in that the cleaning element is moved in the passive state to a first position, where the cleaning element is switched from the passive state to the active state.

15. The method according to claim 14, characterized in that in Sensor means are provided downstream of the application device in the web travel direction to detect a disturbance in the fibrous web, and the first position is determined on the basis of these sensor values.

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