Doctor holder and scraping device

Abstract

A doctor holder and a scraping device of a machine for producing or processing a fibrous web, wherein the doctor 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 doctor blade, and wherein the doctor holder furthermore has at least one application tube which is arranged in an interior space of the doctor holder delimited by the base plate and the top plate, wherein adjustment means are provided, which are designed to press against the application tube via a contact surface and to reduce or to increase the interior space available for the application tube.

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 10.

[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] To achieve a complete cleaning effect, the scraping devices typically extend across the entire width of the roller or cylinder. In modern systems, these scraping devices can extend 10 meters or more. Even with these large sizes, a uniform cleaning effect must be ensured.

[0007] It is therefore an object of the present invention to enable uniform contact pressure of the scraper blade over the entire length of the scraping device, in particular the entire length of the roller. It is also an object of the invention to increase the cleaning performance of the scraping device, reduce the likelihood of deposits passing through, and enable more even wear of the scraper blades used.

[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] A doctor holder for a doctoring device of a machine for producing or processing a fibrous web is proposed, wherein the doctor holder has a base plate and a cover plate, and wherein the base plate and the cover plate can be tilted relative to one another about a rotational axis extending in the longitudinal direction of the doctor holder and thus transversely to the machine direction. The cover plate has a holding device for receiving a doctor blade. In addition, at least one application hose is provided, which is arranged in an interior of the doctor holder that is delimited by the base plate and the cover plate.

[0010] According to the invention, adjustment means are provided which are designed to press on the application hose via a contact surface and to reduce or enlarge the interior space available for the application hose.

[0011] This limits the space within which the hose can expand when pressurized with compressed air. Reducing this space increases the contact pressure of the scraper blade on the roller surface at this point. This is because the applied pressure within the application hose is distributed over a larger contact surface due to the smaller available expansion space. Increasing the space by unscrewing the adjusting screw has the opposite effect. Using such adjustment devices, the contact pressure can be specifically adjusted, thus increasing the cleaning performance of the scraper device and reducing the likelihood of deposits being allowed through.

[0012] Various designs are possible for implementing the adjustment means. For example, it can be provided that at least some, in particular all, of the adjustment means are designed as adjustment screws, which are connected to the cover plate or the base plate by means of threaded holes. In this case, the expansion space is reduced or enlarged by screwing in or out the adjustment screws. Such a design is particularly advantageous because it is very well suited for retrofitting existing scraping devices. For example, a scraping device, as known from WO 2013 019 989, can be very easily upgraded to a scraping device according to one aspect of the present invention by means of a few holes and screws.

[0013] Particularly for profiling the contact pressure, it can be advantageous if a plurality of adjustment means, in particular in the form of the adjustment screws described above, are provided, which are distributed over the length of the doctor holder and thus the cross-machine direction. This makes it possible to adjust the cross-profile of the interior space available as expansion space for the application hose. In preferred embodiments, the distance between two adjacent adjustment means can be between 50 mm and 400 mm, preferably between 70 mm and 250 mm. With a larger distance, only a very coarse profiling is possible. A smaller distance between adjacent adjustment means increases the manufacturing effort, while a finer profiling of the contact pressure is often not necessary.

[0014] The adjustment devices can be evenly distributed so that two adjacent adjustment devices have the same distance between them. Alternatively, the adjustment devices can also be unevenly distributed. For example, the distances at the edge of the scraper holder can be smaller than in the middle. If only adjustment screws are used as adjustment devices, the contact surface with the application hose only consists of the front end of the adjustment screws. In this case, a small metal contact surface is pressed onto the outer wall of the application hose, which is usually made of a polymer such as rubber. There is a risk that the application hose will be damaged by the adjustment screw. To prevent damage to the application hose from the adjustment screws, the tips of the screws can be treated, for example by grinding them down, or they can be provided with an attachment such as a rubber cap.

[0015] Alternatively, you can also enlarge the contact area.

[0016] In such an embodiment, for example, a flexible band may be provided which is arranged between the application tube and at least some, in particular all, of the adjustment means, and wherein the contact surface is provided by the flexible band.

[0017] The flexible tape can be, for example, a metal tape, a polymer tape, a fabric tape or a mixture of these.

[0018] This design is also advantageous because it not only increases the contact area and protects the outer wall of the application hose, but also because it is very simple to implement. Furthermore, such a flexible band can be easily replaced if it becomes worn.

[0019] Alternatively or additionally, one or more wedges can be provided, which are arranged between the application tube and at least some, in particular all, of the adjustment means, and wherein the contact surface is provided by the wedge(s). With regard to increasing the contact surface, this design has the same advantages as the flexible band described above. The wedge shape also makes it possible to provide a certain degree of guidance to the application tube. The wedge(s) can also be made of metal, a polymer material, or a mixture thereof.

[0020] In a particularly preferred embodiment, it can also be provided that the flexible band is designed as a wedge-shaped flexible band.

[0021] In further advantageous embodiments, the scraper holder can be provided with at least one sensor for measuring the contact pressure, in particular a plurality of sensors for measuring a contact pressure profile. Providing such sensors is advantageous because it allows for the detection of uneven contact pressure and the immediate determination of the effect of the adjustment means.

[0022] It is particularly possible that at least one, in particular all, sensors for measuring the contact pressure are provided in or on the adjustment means.

[0023] In an advantageous embodiment, the sensors can be integrated into the flexible band, or provided between the flexible band and the adjustment screws or between the flexible band and the application hose.

[0024] If the sensors are placed between the flexible band and the application tube, the flexible band can protect the sensors from wear or destruction by the adjustment screws.

[0025] A scraping device of a machine for producing or processing a fibrous web can be provided, wherein the scraping device comprises a scraper blade and a scraper holder according to one aspect of the invention.

[0026] The invention is explained below with reference to figures. The invention is not limited to the embodiments shown in the figures.

[0027] The figures show in detail:

[0028] Figure 1 shows a scraping device according to the prior art.

[0029] Figures 2, 3, 4, and 5 schematically show scraping devices according to various aspects of the present invention. Figure 1 shows a scraping device known from the prior art, for example from WO 2013 019 989, comprising a scraper blade 7 and a scraper holder 1. The scraper holder 1 comprises a base plate 2 and a cover plate 3, on which a holding device 6 for the scraper blade 7 is also provided. The base plate 2 is curved. Thus, the base plate 2 provides not only the base but also the front and rear of the scraper holder 1. The cover plate 3, and thus also the scraper blade 7 attached to it, are rotatably mounted on a rotation axis 5. Two hoses are located inside the scraper holder 1: a contact hose 4 and a relief hose 8.

[0030] If the application hose 4 is pressurized, e.g., by means of compressed air, the scraper blade 7 is pressed against the moving surface 20, e.g., a roller surface 20 or a cylinder surface 20. To lift the scraper blade 7 from the moving surface 20, the relief hose 8 can be pressurized.

[0031] Figure 2 now shows a scraping device according to one aspect of the invention. The scraping device shown in Figure 1 is supplemented by adjustment means 10, which are configured to press onto the application hose 4 via a contact surface 11 and to reduce or increase the internal space available for the application hose 4. In Figure 2, these adjustment means 10 comprise a series of adjustment screws 10a, which are distributed along the length of the scraper holder 1, wherein the adjustment screws 10a are connected to the cover plate 3 by means of threaded holes. The distance between two adjacent adjustment screws 10a can be between 50 mm and 400 mm, preferably between 70 mm and 250 mm.In order to prevent damage to the application hose 4 by the adjusting screws 10a, a flexible band 12 is provided in Figure 2, which is arranged between the application hose 4 and the adjusting screws 10a, and wherein the contact surface 11 is provided by the flexible band 12. The embodiment in Figure 3 also supplements the prior art known from Figure 1 with adjusting means 10. Here, too, adjusting screws 10a are provided. In contrast to Figure 2, the adjusting screws 10a are connected to the base plate 2 by means of threaded holes. The adjusting screws 10a are provided in Figure 3 in the part of the base plate 2 that forms the rear wall of the scraper holder 1. This is advantageous because this area is more easily accessible during operation of the scraping device than, for example, the bottom or the front. The contact surface 11 is provided in Figure 3 by the tips of the adjusting screws 10a.In order to avoid damage to the application hose by the screws 10a, these tips can be treated, for example by grinding them down, or they can be provided with an attachment, e.g. a rubber cap.

[0032] Figure 4 shows a variant of the scraping device from Figure 3. A wedge 13 is inserted between the adjusting screws 10a and the application hose 4. This wedge 13 also provides the contact surface 11. The wedge 13 can be made of a metal or a plastic material. A separate wedge 13 can be provided for each adjusting screw 10a. Alternatively, analogous to the flexible band 12, a single, wedge-shaped strip 13 can be provided, extending over the entire length of the scraper holder 1. This wedge-shaped strip 13 can, in particular, also be designed as a flexible, wedge-shaped band 13.

[0033] With regard to the enlargement of the contact surface 11, this design offers the same advantages as the flexible band 12 described in Figure 2. The wedge shape also makes it possible to provide guidance for the application hose 4. If, for example, the wedge 13 tapers towards the cover plate 3, the application hose 4 is guided towards this cover plate 3 when the adjusting screws 10a are tightened.

[0034] Figure 5 shows a further embodiment of a scraping device according to aspects of the invention. Here, the adjustment means 10 are again implemented by adjustment screws 10a, as in Figure 2. A flexible band 12 is provided between the adjustment screws 10a and the application hose 4, providing the contact surface 11 to the application hose 4. In contrast to Figure 2, however, in Figure 4 the adjustment screws 10a are not provided in the cover plate 3, but in the base plate 2. The enlargement or reduction of the interior space in this embodiment therefore occurs 'from below'. The choice of the side on which the adjustment means 10 are arranged on the scraping device generally depends on the installation situation of the scraping device. While installation in the cover plate 3 is often desirable for manufacturing reasons, in some cases this may not be practical due to the poor accessibility of this side when the scraping device is installed.In these cases, an arrangement in the base plate 2, and there in particular in the underside or in the rear wall, is also possible.

[0035] List of reference symbols

[0036] 1 scraper holder

[0037] 2 Base plate 3 Cover plate

[0038] 4 Attachment hose

[0039] 5 axis of rotation

[0040] 6 Holding device

[0041] 7 Scraper blade 8 Relief hose

[0042] 10 Adjustment tools

[0043] 10a Adjusting screw

[0044] 11 Contact surface

[0045] 12 flexible band 13 wedge

[0046] 20 moving surface

Claims

Patent claims 1. Scraper holder (1 ) for a scraping device of a machine for the production or processing of 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 each other about a rotational axis (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 comprises at least one feed tube (4) which is arranged in an interior space of the scraper holder (1 ) which is bounded by the base plate (2) and the cover plate (3), characterized in that adjusting means (10) are provided which are configured to press on the feed tube (4) via a contact surface (11) and to reduce or enlarge the interior space available for the feed tube (4).

2. Scraper holder (1 ) according to claim 1 , characterized in that at least some, in particular all, adjusting means (10) are designed as adjusting screws (10a) or comprise them which are connected to the cover plate (3) or the base plate (2) by means of threaded bores.

3. Scraper holder (2) according to claim 1 or 2, characterized in that a plurality of adjusting means (10) are arranged distributed over the length of the scraper holder (1 ), wherein the distance between two adjacent adjusting means (10) is between 50mm and 400 mm, preferably between 70mm and 250 mm.

4. Scraper holder (1) according to the preceding claims, characterized in that a flexible band (12) is provided which is between the application hose (4) and at least some, in particular a scraper holder (1) according to claim 4, characterized in that the flexible band (12) is a metal band, a polymer band, a fabric band, or a mixture thereof. a scraper holder (1) according to claim 3, characterized in that a wedge (13) or wedges (13) are provided, which are arranged between the application hose (4) and at least some, in particular all, of the adjustment means (10), and wherein the contact surface (11) is provided by the wedge(s) (13). a scraper holder (1) according to claim 6, characterized in that at least one wedge (13), in particular all wedges (13), are made of metal, a polymer material, or a mixture thereof.A scraper holder (1) according to one of the preceding claims, characterized in that the scraper holder (1) has at least one sensor for measuring the contact pressure, in particular a plurality of sensors for measuring a contact pressure profile. A scraper holder (1) according to claim 6, characterized in that at least one, in particular all, sensors for measuring the contact pressure are provided in or on the adjusting means (10). A 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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