Scraper holder and scraping device

Abstract

A scraper holder and a scraping device of a machine for producing or processing a fibrous web, wherein the scraper holder has a base plate and a top plate, wherein the base plate and the top plate are tiltable relative to each other about an axis of rotation extending transversely with respect to the machine direction, and wherein the top plate has a holding device for receiving a scraper blade, and wherein the scraper holder furthermore has at least one application tube which is arranged in an interior space of the scraper holder delimited by the base plate and the top plate, a plurality of cleaning openings being provided in the base plate to allow liquid and / or dirt particles to exit the interior space.

Description

[0001] Scraper holder and scraping device

[0002] The invention relates to a doctor holder for a doctoring device of a machine for producing or processing a fibrous web according to the preamble of claim 1 and to an associated doctoring device according to the preamble of claim 12.

[0003] During the production and processing of fibrous webs such as paper or cardboard webs, the fibrous web is passed over a multitude of rollers and cylinders.

[0004] In order to keep the surfaces of these rollers and cylinders free of deposits during operation, it is known to provide suitable scraping devices which mechanically remove possible deposits from the respective surface.

[0005] The scraping devices typically comprise a scraper blade, which is in contact with the surface and is regularly replaced as a wear part, as well as a scraper holder to which the scraper blade is attached. The scraper holder can then have suitable hose devices for applying and removing the scraper blade. Such scraping devices are known, for example, from WO 2013 019 989. Such a scraping device is also shown in DE102019117901 A1.

[0006] During use, these scraping devices are usually exposed to very high levels of moisture and various types of dirt particles. Over time, this leads to contamination of these scraping devices, which can require the device to be removed from the machine and cleaned. However, this is only possible when the system is shut down. Furthermore, the necessary effort generates costs for the operator.

[0007] The object of the present invention is therefore to propose a scraping device that can operate reliably for a long time, even under difficult operating conditions. It is also an object of the invention to propose a scraping device that needs to be removed from the production facility less frequently for maintenance and servicing.

[0008] These objects are achieved according to the invention by a scraper holder according to claim 1, as well as a scraping device using such a scraper holder. Further advantageous embodiments of the present invention can be found in the subclaims.

[0009] With regard to the doctor holder, the objects are achieved by a doctor holder for a doctoring device of a machine for producing or processing a fibrous web. The doctor holder has a base plate and a cover plate, wherein the base plate and the cover plate are tiltable relative to one another about a rotational axis extending transversely to the machine direction. The cover plate has a holding device for receiving a doctor blade. Furthermore, the doctor holder has at least one contact hose, which is arranged in an interior of the doctor holder, which is delimited by the base plate and the cover plate.

[0010] According to the invention, one or more cleaning openings are provided in the base plate to allow liquid and / or dirt particles to escape from the interior to the outside.

[0011] Furthermore, a scraping device of a machine for producing or processing a fibrous web is proposed, wherein the scraping device comprises a scraper blade and a scraper holder, and the scraper holder is designed according to one aspect of the invention.

[0012] The inventors have recognized that a large proportion of malfunctions during the operation of scraping devices result from liquids and particles penetrating the interior of the scraper holder. These dirt particles can then accumulate on the rotary axis or the hoses, for example, and over time impair the functioning of the scraper device. In addition, the liquids used in a paper machine, for example, are often loaded with a very high amount of dissolved or dispersed substances, such as mineral fillers used in paper production such as CaCO3. If such a liquid (usually water) penetrates the interior of the scraper holder, these substances can precipitate and also become deposited on moving and immobile elements. This then often occurs in the form of incrustations (“calcification”).

[0013] The inventors' idea to solve this problem is based on the realization that preventing the penetration of dirt and moisture by completely sealing the scraper holder is not possible at a reasonable cost.

[0014] Instead, a plurality of cleaning openings are provided in scraper holders according to aspects of the present invention. While these cleaning openings encourage the penetration of liquid and particles into the scraper holder, which at first glance appears to contradict the task to be solved, the contaminated water also drains quickly from the interior of the scraper holder through these cleaning openings, so that dissolved substances do not have sufficient time to deposit on parts of the scraper holder. Thus, the contaminated water no longer contributes significantly to the contamination of the interior of the scraper holder. On the contrary, the interior is rinsed and thus cleaned by this water. Should dirt particles such as fiber fragments or similar accumulate in the interior for any reason, they are flushed out again through the cleaning openings by the process water that is already present.

[0015] This creates a scraping device that is at least partially self-cleaning. This significantly extends the scraping device's service life before maintenance and, if necessary, removal are necessary.

[0016] Furthermore, a doctor holder according to aspects of the invention is also advantageous in applications in which little or no process water is generated, such as in the drying section of a paper machine. Although automatic flushing with process water is omitted there, there is a risk that only a portion of the dry dirt particles that penetrate will escape through the cleaning openings. However, when the machine is at a standstill, it is possible to very easily clean the doctor holder from the outside using a hose or high-pressure cleaner without dismantling it. The water will penetrate the interior through the cleaning openings, pick up the particles, and flush them back out through the cleaning openings. Thus, with doctor holders according to aspects of the invention, the period until maintenance and, if necessary, dismantling is necessary can be significantly extended in this application as well.

[0017] The design, geometry and number of cleaning openings can vary depending on the model.

[0018] For example, it can be provided that at least some, in particular all, cleaning openings are designed as bores and have a diameter of more than 3 mm, in particular more than 5 mm, preferably 8 mm or more.

[0019] Alternatively or additionally, at least some, in particular all, of the cleaning openings can be designed as slots, wherein the slots have a width of at least 3 mm, in particular at least 5 mm, preferably 8 mm or more, and / or a length of at least 10 mm, in particular at least 15 mm or at least 30 mm. Longer slots are also possible. Longer slots, in particular, can be oriented in the longitudinal direction of the scraper holder, and thus, in the installed situation, in the cross-machine direction.

[0020] Example slot dimensions can be 3mm x 15mm, 5mm x 30mm, 8mm x 50mm or 7mm x 40mm.

[0021] The type of raw material used in production can also play a role in the selection of the size of the cleaning openings. For example, softwood sulfate pulp has long, strong fibers averaging 3.3 mm in length. Hardwood pulp, on the other hand, has shorter fibers of approximately 1 mm in length. To avoid the risk of fiber clogging of the cleaning openings, smaller opening cross-sections (e.g., from 3 mm) are sufficient when using hardwood pulp, whereas larger opening cross-sections of, for example, 5 mm or more are advantageous for softwood pulp. However, since other factors besides fiber length also play a role in clogging, even larger openings can be helpful.

[0022] The open area, i.e., the proportion of cleaning openings to the total area of ​​the base plate, can be at least 5%, preferably between 5% and 20%, particularly preferably between 6% and 13%, for example, 7%. A compromise must always be found here. A large open area allows for rapid water drainage, but leads to destabilization of the base plate and also carries the risk of damage to the connecting hose due to mechanical influences. The specified ranges have proven to be a good compromise.

[0023] In advantageous designs, the base plate can be made entirely or partially from perforated sheet metal. Such perforated sheets are commercially available in various materials and with various hole patterns, or are very easy to manufacture. Such perforated sheets can then be formed into the desired shape or further processed like unperforated sheets.

[0024] Alternatively, or additionally, the cleaning holes can also be added after the scraper holder or base plate has been manufactured. While this is more complex in terms of manufacturing than using a perforated sheet, the cleaning holes can be positioned precisely where desired.

[0025] An example of this is the common case in which the base plate is designed in the form of a tray. In this case, it can be advantageous if at least some cleaning openings, in particular all cleaning openings, are arranged in the area of ​​at least one of the bending radii of the tray. Experience has shown that the tendency for deposits to build up is high at the points of these bending radii. In addition, in many installation positions, these points are the lowest point of the scraper holder, so that the liquids flow to these points by gravity and can reliably escape through the cleaning openings provided there. For cleaning openings provided at such bending radii, it can be particularly advantageous if these cleaning openings are designed as slots. Such slots can be easily placed in the right places during production.

[0026] A cleaning opening is also “within the range of a bending radius” if only part of the cleaning opening protrudes into the curved part of the tub.

[0027] Especially with small bend radii, it may happen that some or all of the cleaning openings do not extend directly into the curved part of the tub. Such openings should nevertheless be considered "within the bend radius" if their distance from the curved part of the tub is less than 5 mm, and especially less than 3 mm.

[0028] In a further, very preferred embodiment of the scraper holder, it can be provided that the scraper holder has a flushing device which is designed to supply the interior of the scraper holder with a liquid or gaseous flushing medium.

[0029] Suitable rinsing media here are water, which may be mixed with suitable cleaning agents (e.g. surfactants or acids to dissolve the limescale).

[0030] Such designs enable highly targeted cleaning of the scraper holder, even in installation situations where direct rinsing with process water is not possible or not sufficient. The rinsing devices can also be specifically directed at critical points that are either highly prone to contamination or that, if contaminated, would quickly impair the functionality of the scraper device.

[0031] Such flushing devices can be implemented in various ways. For example, it is generally possible to install hoses or lines for compressed air or water inside the scraper holder.

[0032] Since the installation space is limited in many installation positions of the scraping devices, an enlargement of the scraping device should be avoided if possible.

[0033] It can therefore be advantageous if the flushing device is designed as a spray tube that is arranged along the axis of rotation. In this case, the flushing device can perform a dual function. In addition to the cleaning function, the spray tube can serve as a rotating hub for rotating the cover plate. In many cases, this rotating hub is already designed as a tube and can be converted into a suitable flushing device with little effort. Suitable spray tubes can have an inner diameter of between 6mm and 10mm, with an outer diameter between 8mm and 13mm. With smaller (inner) diameters, it is often not possible to deliver enough flushing medium, while larger (outer diameters) can only be fitted into the usually available installation spaces with difficulty.

[0034] To supply the flushing medium, the scraper holder can be provided with at least one flushing medium supply located on the base plate. Providing a supply on the base plate is very easy to implement.

[0035] Alternatively, the scraper holder can be provided with a supply for a flushing medium, which is arranged on at least one end face of the scraper holder. This can be advantageous since the supply lines with pressure medium for the application hose and the lifting hose are already provided on the end face. Depending on the application and, for example, also depending on the length of the scraper device, multiple supplies can also be provided to ensure a uniform supply of flushing medium to the scraper device.

[0036] In further advantageous embodiments, the scraper holder can be provided with a plurality of scraper holder segments arranged side by side in the longitudinal direction (L). Each scraper holder segment comprises a base plate segment and a cover plate segment. In this way, the scraper holder can be constructed in a modular manner.

[0037] Such a scraper holder segment has one or more cleaning openings in the base plate segment to allow liquid and / or dirt particles to escape from the interior to the outside.

[0038] Such a scraper holder is no longer manufactured in one piece, but consists of several standardized, short segments. This offers several advantages. For example, in the event of damage, the entire scraper holder does not need to be replaced. Instead, replacing individual segments—either the scraper holder segments or just a base plate segment or cover plate segment—is sufficient to restore the functionality of the scraper holder.

[0039] The scraper holder can be designed to be segmented into equally sized, standardized units. These segments can, for example, be designed in a length range of 60cm - 130cm, particularly, and preferably 60 - 120cm. This simplifies logistics, for example, during shipping, as standard packaging units (e.g., standardized pallets) can be used, whereas a non-segmented scraper holder with a length of 10m usually has to be transported as special cargo.

[0040] The hoses used, i.e., the contact hose and the relief hose, are designed as continuous hoses, even with segmented scraper holders, extending in one piece over the entire length of the scraper holder. This is not a problem, however, as these hoses can still be easily transported when rolled up, even at greater lengths. This standardization allows the user to keep only a few segments in stock, rather than one or more entire scraper holders, in order to be able to carry out repairs in the event of damage.

[0041] At most, the starting and ending segments (the outer segments) will usually be "special components" due to the different overall lengths of the roller to be doctored and the hose guides to be attached. These components do not conform to the specified standard dimensions but must be adapted to the specific installation situation. However, even these special components can then be easily shipped.

[0042] The adjacent scraper holder segments are connected by the scraper blade, which is advantageously designed as a continuous blade. Each cover plate segment advantageously also has a holding device for holding the scraper blade.

[0043] In addition, the individual segments of the scraper holder are attached to a frame, which also creates a connection.

[0044] Additionally, if necessary, further means for connecting and adjusting adjacent scraper holder segments may be provided. For example, dowel pins or guide grooves and springs may be provided to connect adjacent segments to one another.

[0045] In principle, it is also possible for the rotation axis to be segmented. Rotation axis segments of adjacent scraper holder segments can then be connected to each other if necessary.

[0046] In a particularly preferred embodiment, however, a continuous rotation axis can be provided. This has the advantage that the connection of the scraper holder segments to one another is at least partially also achieved via the rotation axis. This is also advantageous in designs in which a flushing device is provided, and the rotation axis is particularly designed as a flushing device. A continuous spray tube can be used here. This eliminates the effort of having to tightly connect individual spray tube segments to prevent the pressurized flushing medium from escaping at the connection points.

[0047] While this requires a spray tube the length of the entire scraper holder, such relatively simple components can usually be sourced locally and do not need to be purchased from specialized workshops, possibly far away. Therefore, this disadvantage is hardly significant.

[0048] The invention is explained in more detail below with reference to schematic figures. The invention is not limited to the embodiments shown in the figures.

[0049] Figures 1 to 3 each show a scraping device according to an aspect of the present invention.

[0050] Figure 4 shows a section of a base plate for a scraper holder according to one aspect of the invention.

[0051] Figure 5 shows a scraping device according to another aspect of the present invention.

[0052] The scraping device in Figure 1 comprises a base plate 2 and a cover plate 3, which form an interior space 9 of the scraper holder 1. A holding device 6 for receiving a scraper blade 7 is provided on the cover plate 3. The scraper blade 7 can be a conventional scraper blade 7 known from the prior art. The base plate 2 and the cover plate 3 are designed to be tiltable relative to one another about an axis of rotation 5 extending transversely to the machine direction. A contact hose 4 and a relief hose 8 are provided in the interior space 9 of the scraper holder 1. If the contact hose 4 is subjected to pressure, the cover plate 2 is tilted about the axis of rotation 5. This causes the scraper blade 7 to rest against a moving surface 20. The moving surface 20 can be, for example, the surface of a roller or a drying cylinder in a machine for producing or processing a fibrous web.To ensure safe lifting of the scraper blade 7 from the running surface 20, the relief hose 8 can be pressurized while the application hose 4 is relieved of pressure. This causes the cover plate 3 to tilt back around the rotation axis 5 in the other direction, and the contact of the scraper blade 7 with the running surface 20 is released.

[0053] The base plate 2 is provided with a series of cleaning openings 10. These cleaning openings 10 allow liquid and / or dirt particles to be removed from the interior 9 to the outside. In the scraping device in Figure 1, the base plate 2 is made of a perforated sheet. In particular, the cleaning openings 10 can be evenly distributed over the entire base plate 2. Such perforated sheets usually have round holes as cleaning openings 10. The holes can, in particular, have a diameter of more than 3 mm, preferably more than 5 mm.

[0054] The scraping device in Figure 2 differs from the device in Figure 1 in that no perforated sheet was used to produce the base plate 2, but rather the cleaning openings 10 were specifically introduced into the base plate 2 at specific locations. The base plate 2 is designed in the form of a trough. This trough has bending radii 12 at the transition between the floor and the wall. In the example in Figure 2, the cleaning openings 10 are arranged in the region of at least one of the bending radii 12 of the trough 2. Advantageously, it can be provided that the cleaning openings 10 are designed as slots, wherein the slots can in particular have a width of at least 3 mm, preferably at least 5 mm, and / or a length of at least 10 mm, in particular at least 15 mm.

[0055] The scraping device in Figure 3 shows a design in which a rinsing device 11 is provided in the interior 9 of the scraper holder 1. The rinsing device 11 is designed as a rinsing pipe 11 which is arranged along the rotation axis 5. In this case, the rinsing device 11 can perform a dual function. In addition to the cleaning function, the spray pipe 11 can serve as a rotary hub for rotating the cover plate 3. The rinsing device 11 has an outlet for a rinsing medium 11a. This outlet can be arranged such that the rinsing medium 11a is directed specifically at the points where the risk of contamination is greatest. Several outlets can also be provided, directed at different locations. The position of the cleaning openings 10 can also be adapted to the direction of the rinsing device 11.

[0056] To supply the flushing device 11 with the required flushing medium 11a, a supply line 13 is provided. A suitable media line, e.g., a water hose or a compressed air line, can then be connected to this supply line 13. The supply line 13 is provided, as an example, on the base plate 2 in Figure 13. Particularly in the case of long scraping devices, several spaced-apart supplies 13 can also be provided here. Alternatively, the scraper holder 1 can be provided with a supply line 13 for a flushing medium 11a, which is arranged on at least one end face of the scraper holder 1.

[0057] Such a flushing device 11 can also be provided in particular in the embodiments of Figures 1 and 2.

[0058] Figure 4 shows a schematic top view of a base plate 2 for a scraper holder 1 according to one aspect of the invention. The base plate 2 is designed as a perforated sheet, or more specifically, as a slotted sheet. The slots 10 serve as cleaning openings 10 in the scraper holder 1. The slots are oriented in the longitudinal direction L of the scraper holder 1 and thus extend in the cross-machine direction when installed.

[0059] In the design shown in Figure 4, the cleaning openings 10 are arranged in two rows. These rows are each located at the position of the bending radius 12. By bending the base plate 2 at the points of these bending radii 12, the front and back of the scraper holder 1 are created. This type of production is advantageous because it allows the cleaning openings 10 to be placed very precisely and precisely at the critical points of the bending radii 12. Furthermore, it can be achieved that comparatively large openings 10 are provided at the points of the bending radii 12 - thereby increasing the cleaning effect - while at the same time the total open area of ​​the base plate 2 remains small. This has a beneficial effect on the stability of the base plate and ensures good protection of the application hose 4 and the relief hose 8 against mechanical damage.Advantageous dimensions for the slots 10 are a width of 4mm-6mm and a length between 30mm and 60mm and an open area between 6% and 13%.

[0060] Figure 5 shows a scraper holder 1 according to a further aspect of the invention. The scraper holder 1 is constructed from scraper holder segments 1a arranged side by side in the longitudinal direction L. Each of the scraper holder segments 1a has a base plate segment 2a and a cover plate segment 3a. In addition, each scraper holder segment 1a comprises a holding device 6 for receiving a scraper blade 7. The scraper blade 7 is designed here as a continuous, non-segmented scraper blade 7. While the entire scraper holder 1 can have a length of 10 m or more, the scraper holder segments are significantly shorter, usually only having a length between 60 and 130 cm.

[0061] Both the application hose 4 and the relief hose 8 are continuous, i.e., not segmented. Each scraper holder segment 1a has one or more cleaning openings 10 in the base plate segment 2a to allow liquid and / or dirt particles to escape from the interior to the outside. In the embodiment shown in Figure 5, slots 10 are provided for this purpose, which are arranged at and along the bending radius 12. Furthermore, the scraper holder has a rinsing device 11, which is designed as a spray tube 11, which is arranged along the rotation axis 5. This spray tube 11 is also advantageously continuous, i.e., not segmented. This not only avoids problems with the tightness at the connection points of adjacent spray tube segments, but the continuous spray tube 11 can also at least partially assume the function of connecting and adjusting adjacent scraper holder segments 1a. List of Reference Symbols

[0062] 1 scraper holder

[0063] 1a Scraper holder segment

[0064] 2 base plate

[0065] 2a Base plate segment

[0066] 3 Cover plate

[0067] 3a Cover plate segment

[0068] 4 Attachment hose

[0069] 5 axis of rotation

[0070] 6 Holding device

[0071] 7 scraper blade

[0072] 8 Relief hose

[0073] 9 Interior

[0074] 10 Cleaning opening

[0075] 11 Flushing device

[0076] 11a Flushing medium

[0077] 12 Bending radius

[0078] 13 Feed

[0079] 20 moving surface

[0080] L Length direction (= CD)

Claims

Patent claims 1. Scraper holder (1) for a scraping device of a machine for producing or processing a fibrous web, wherein the scraper holder (1) has a base plate (2) and a cover plate (3), wherein the base plate (2) and the cover plate (3) are tiltable relative to one another about an axis of rotation (5) extending transversely to the machine direction and wherein the cover plate (3) has a holding device (6) for receiving a scraper blade (7), and wherein the scraper holder (1) further has at least one application hose (4) which is arranged in an interior space (9) of the scraper holder (1), which is delimited by the base plate (2) and the cover plate (3), characterized in that one or more cleaning openings (10) are provided in the base plate (2) in order to allow liquid and / or dirt particles to escape from the interior space (9) to the outside.

2. Scraper holder (1) according to claim 1, characterized in that at least some, in particular all, cleaning openings (10) are designed as bores (10), and the bores (10) in particular have a diameter of more than 3 mm, preferably more than 5 mm, in particular 8 mm or more.

3. Scraper holder (1) according to one of the preceding claims, characterized in that at least some, in particular all, cleaning openings (10) are designed as slots (10), wherein the slots (10) in particular have a width of at least 3 mm, preferably at least 5 mm, and / or a length of at least 10 mm, in particular at least 30 mm 4. Scraper holder (1) according to one of the preceding claims, characterized in that the base plate (2) is designed in the form of a trough. Scraper holder (1) according to claim 4, characterized in that at least some cleaning openings (10), in particular all cleaning openings (10), are arranged in the region of at least one of the bending radii (12) of the trough. Scraper holder (1) according to one of the preceding claims, characterized in that the scraper holder (1) has a rinsing device (11) designed to supply the interior (9) of the scraper holder (1) with a liquid or gaseous rinsing medium (11a). Scraper holder (1) according to claim 6, characterized in that the rinsing device (11) is designed as a spray tube (11) arranged along the axis of rotation (5). Scraper holder (1) according to one of claims 6 or 7, characterized in that the scraper holder (1) has a supply (13) for a rinsing medium (11a), which is arranged on the base plate (2).Scraper holder (1) according to one of claims 6 to 8, characterized in that the scraper holder (1) has a supply (13) for a flushing medium (11a), which is arranged on at least one end face of the scraper holder (1). Scraper holder (1) according to one of the preceding claims, characterized in that the scraper holder (1) has a plurality of scraper holder segments (1a) which are arranged next to one another in the longitudinal direction (L), wherein each scraper holder segment (1a) comprises a base plate segment (2a) and a cover plate segment (3a). Scraper holder (1) according to claim 10, characterized in that the scraper holder segments (1a) are connected to one another at least partially via a continuous axis of rotation (5), wherein the axis of rotation (5) is designed in particular as a flushing device (11). Scraping device of a machine for producing or processing a fibrous web, wherein the scraping device comprises a scraper blade (7) and a scraper holder (1), characterized in that the scraper holder (1) is designed according to one of the preceding claims.

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