EP4305237A1

EP4305237A1 - Doctor blade and roll device

Info

Publication number: EP4305237A1
Application number: EP22709967.8A
Authority: EP
Inventors: Hubert Bischof; Martin HEINIG
Original assignee: Voith Patent GmbH
Current assignee: Voith Patent GmbH
Priority date: 2021-03-09
Filing date: 2022-02-14
Publication date: 2024-01-17
Also published as: DE102021105618A1; WO2022189093A1

Abstract

The invention relates to a doctor blade for scraping the lateral surface of a rotatable body and to a corresponding roll device, the doctor blade comprising a main body, which has an end surface for contacting the lateral surface and has lateral surfaces adjoining the longitudinal edges of the end surface, and a first outer layer, which is disposed on a first of the two lateral surfaces, characterized in that the first outer layer comprises a woven fabric or laid fabric composed of reinforcing fibers, which is embedded in a polymer matrix, the angle between the reinforcing fibers and the end surface being 30° or more.

Description

scraper blade and roller device

The invention relates to a scraper blade for scraping the lateral surfaces of rotary bodies, for example rollers, belts, sieves and felts, such as are used in particular in paper, cardboard and corrugated board machines, printing machines and calenders, and a roller device which is scraped using such a blade.

Doctor blades are used in the paper and printing industry to clean the surfaces of rotating rollers, which are usually covered. In papermaking, scraper blades are used to remove the liquid film on the roll covers, to clean the roll surfaces of contaminants such as paper fibers or coating residues and to condition the roll surfaces. In addition, the doctor blades prevent the paper web from wrapping itself around the web in the event of a web break

roller wraps and thereby damages the paper machine. In order to be able to reliably fulfill these tasks, the scraper blade rests against the outer lateral surface of the respective roll or the respective roll cover with a certain pressure. In addition to cleaning rollers, doctor blades are also used in a corresponding manner to clean and condition circulating belts, belts, screens and felts. Due to the high pressure with which the scraper blade on the

If the roller surface presses, the contact pressure is usually 150 N/m (indicated as contact force in relation to the length of the doctor blade) and more, high demands are placed on the wear resistance or abrasion resistance of the doctor blades. Since the geometry of the surface of a scraper blade that comes into contact with the roll surface does not match the geometry of the scraped blade with the required accuracy

roller surface can be adapted, there are always minor deviations in the geometries of the two surfaces lying on top of one another at the beginning of the use of a scraper blade, which are only compensated for in the course of an initial grinding-in process, the so-called "running in" of the blade will. Paper produced during the break-in time required for this is often of inferior quality, so that the paper manufacturers insist on the shortest possible break-in times. However, it has been shown that with conventional scraper blades, the change in blade geometry caused by abrasion during running-in and later scraping tends to be rounded or flattened

Blade edges with the result of a reduced scraping effect. In the documents EP 1 683 915 and DE 10 2010 001 306 by the same applicant, it is proposed to eliminate this problem by providing the base body of a scraper blade with a layer that has a higher abrasion resistance than the base body. As explained in this document, the blade is continuously re-sharpened during operation, which prevents the blade edges from rounding.

When using these blades, however, it has been shown that with continued wear, a kind of sawtooth profile sometimes develops over the length of the blade - i.e. the transverse direction of the scraped roller - which causes the contact of the blade to the roller and thus the cleaning effect of the blade or the roller the removal of the paper web from the roll is reduced. This subsequently leads to the passage of paper and deposited dirt, which subsequently leads to premature replacement of the scraper blade or, if not replaced, to massive damage to the system.

It is therefore an object of this invention to propose a scraper blade which can still fulfill its function even with continued wear. It is a further object of the invention to even out the closure of the doctor blade in its longitudinal direction—that is, the transverse direction of the scraped roller—and to avoid or at least reduce sawtooth formation. These objects are completely solved by a scraper blade according to the characterizing part of claim 1 and a roller device according to the characterizing part of claim 14. Advantageous embodiments are described in the subclaims.

The object is achieved by a scraper blade for scraping the lateral surface of a rotatable body, the scraper blade comprising:

- a base body which has an end face for contacting the lateral surface and side faces adjoining the longitudinal edges of the end face, and

- a first outer layer arranged on a first of the two side faces.

According to the invention it is provided that the first outer layer comprises a woven fabric or scrim made of reinforcing fibers which is embedded in a polymer matrix, the angle between the reinforcing fibers and the end face being 30° or more, in particular between 60° and 80°.

The rotatable body can be, for example, a roller, a belt, a screen or a felt, such as are used in particular in paper, cardboard or printing machines.

Such scraper blades usually have a thickness of a few millimeters, in particular 3mm or less.

The length of the blade depends on the dimensions of the body to be scraped. In the case of a roller, this is usually the axial extent of the roller. In modern paper machines, the length of the blade can be more than 10m. The width of a scraper blade is usually in the range between 50mm and 105mm, mostly 75mm. It is known from the prior art already cited to provide an outer layer with reinforcing fibers. The reinforcing fibers are oriented in the length and width direction of the doctor blade. On the one hand, this is due to that the stiffness of the blade in length and width direction can be easily influenced by a suitable choice of fibers. On the other hand, this is also due to the manufacturing process of the blades. These are produced as a quasi-endless roll, ie more than 100m long, which has the width of the blade and from which pieces of the required lengths are then cut off. If a fabric is used for reinforcement, the warp threads of any length are inevitably oriented in the length direction of the blade and the weft threads in the width direction of the blade. However, such an orientation of the reinforcing fibers has the disadvantage that they wear very unevenly. The inventors have recognized that fibers that are oriented in the length direction of the blade, and thus lie parallel to the end face, are destroyed in a very short time when they come into contact with the rotating body, and are also torn out of the polymer matrix or out of the blade, while the perpendicular fibers oriented thereto remain. Since these vertical fibers wear out more slowly than the polymer matrix in between, a sawtooth-like structure develops on the end face.

In order to avoid this sawtooth formation, the reinforcing fibers are embedded in the present invention in such a way that they do not lie parallel to the end face. An angle between the reinforcing fibers and the end face of 30° or more has proven to be sufficient. In particular, angles between 30° and 85°, preferably between 45° and 80° - for example 60°, have proven to be advantageous.

With such a sufficient deviation of the reinforcing fibers from the parallel to the end face, the detachment or tearing of the fibers from the matrix composite can be avoided. Blade tip wear is slower and more even. In particular, the sawtooth formation described above is avoided. Depending on the application, it may be necessary for the scraper blade to include a second outer layer which is arranged on the second side face of the base body. While the second outer layer can in principle be of any design, a structure analogous to that of the first outer layer can also be advantageous for this second outer layer in order to avoid sawtooth formation. The second outer layer can therefore also comprise a fabric or scrim made of reinforcing fibers embedded in a polymer matrix, with the angle between the reinforcing fibers and the end face being more than 30°, in particular between 30° and 85°, preferably between 45° and 80° - is, for example, 60°.

The reinforcing fibers of the first outer layer and/or the second outer layer can be selected depending on the effect to be achieved. In particular, these can be glass fibres, aramid fibres, mineral fibres, carbon fibres, or combinations thereof. If two outer layers are provided, they can have the same or different types of fibers.

In preferred embodiments, the first outer layer and the second outer layer can be identical.

It will often be desirable or necessary to incorporate reinforcing fibers having different orientations into one or both of the outer layers. It is advantageous here if all the reinforcing fibers—or at least almost all the reinforcing fibers—are inclined by 30° or more, in particular between 30° and 85°, preferably between 45° and 80°, with respect to the end face.

In particular, it can be advantageous for the first outer layer and/or the second outer layer to have first reinforcement fibers and second reinforcement fibers that have different orientations, with the first reinforcement fibers enclosing a first angle of between 30° and 80° with the end face, while the second reinforcement fibers enclose a second angle between - 30° and - 80° with the end face. The negative angle specifications of the second reinforcement fibers, which are explained in more detail again in the figures, are intended to simplify the specification of how the first and second reinforcement fibers are arranged in relation to one another. An angle of -45° or -60° etc. should nevertheless be regarded as an "angle between the reinforcing fibers and the end face of 30° or more" within the scope of this application.

In particularly preferred embodiments it can be provided that the first angle and the second angle are equal in terms of absolute value. In woven fabrics, the warp and weft threads are almost perpendicular to each other. In order to do this, the warp and weft threads are cut obliquely from the fabric tape according to the criterion of the angle to the front face around the fabric strip used. The advantage of using fabrics is that a desired minimum angle relative to the end face can be achieved very easily by selecting the cutting angle. In this way it can be achieved, for example, that the warp threads (=first reinforcing fibers) have an angle of +45° and the weft threads (=second reinforcing fibers) have an angle of -45°. However, the disadvantage of using fabrics is that the length of the scraper blades is limited in this way. From a fabric that is 100m long and 1m wide, for example, only a strip of about 1.4m in length can be cut out at an angle of 45°. For many applications, however, significantly longer scraper blades with a length of 10 m or more are required.

You are significantly more flexible when using scrims. Here, fibers of different orientation do not have to be perpendicular to one another. It is possible to lay webs with a very large length (>100m) and small width (e.g. 1m or 1.2m), in which the fibers - for example carbon fibers - are already in the orientation that is later desired in the doctor blade (e.g. +60 ° and - 60°). This also makes it possible in a very simple manner to produce very long doctor blades according to one aspect of the present invention. Advantageously, it can also be provided that the reinforcing fibers of one or both outer layers are oriented in more than two directions. This can be achieved, among other things, by arranging two layers of fabric or non-crimp fabric one on top of the other in an outer layer, for example a non-crimp fabric with -60°/+60° oriented fibers combined with a non-crimp fabric with -45°/+45° oriented fibers. The two scrims can then be made up of the same fibers. However, it can also offer advantages if the two layers are made up of different fibers, which can then perform different functions - for example one layer to increase abrasion resistance and the other to better stiffen the blade

In embodiments of the invention in which the reinforcing fibers of one or both outer layers are oriented in more than two directions, it can also be quite possible that some of the reinforcing fibers also have an angle of less than 30° to the end face. Due to the fact that in this case reinforcement fibers are already provided in two directions with a larger angle in the scraper blade, the structure has sufficient wear resistance, so that the additional reinforcement fibers, which are e.g. only 15° or even only 0° inclined to the end face, either remain in the composite or, in the event of a fire being released from the blade, the remaining reinforcing fibers prevent the formation of a sawtooth structure.

In preferred embodiments, a scrim can be provided in an outer layer, in which the first and second reinforcing fibers are at angles of, for example, -30°/+30°, -45°/+45°, -60°/+60° or -30° /+60° compared to the end face and additionally a fabric or scrim with third and fourth reinforcing fibers, which have an angle of 0°/90° compared to the end face.

Alternatively, a biaxial, triaxial or quadraxial fabric (e.g. a carbon fiber fabric) can be used for each outer layer. As a result, a three or four-fold orientation of the fibers can be achieved even with a single textile element per outer layer. For example, in order to ensure the initially described continuous regrinding of the blade, provision can be made for the first outer layer and/or the second outer layer to be more abrasion-resistant than the base body.

In order to achieve this, it can be provided, for example, that the base body comprises a non-woven fabric that is embedded in a polymer matrix. The random fibers can, for example, comprise or consist of fibers made of a polymer such as PET, PES, PP, PE or viscose and/or natural fibers such as hemp, flax or cotton.

Alternatively it can be provided that the base body comprises a foam material which is embedded in a polymer matrix, wherein the foam material can be formed from a natural foam or a plastic foam.

The plastic foam can consist of the same materials as the random fibers described above. Alternatively, it can also be a PU or epoxy foam.

A honeycomb structure (“honeycomb”) can also be used as an alternative to plastic foam.

The proportions of the individual components of the base body can differ significantly depending on the design.

For example, the base body can have between 0-30% by volume, especially between 8% by volume and 20% by volume of random fibers or foam, while the rest of the base body consists of matrix material including filler.

Alternatively, the base body can have, for example, between at least 75% by volume, in particular between 75% by volume and 90% by volume, of foam, while the rest of the base body consists of matrix material including filler. The polymer matrix of the first outer layer and/or the second outer layer and/or the base body can be an epoxy matrix or a thermoplastic matrix.

The polymer matrix of the first outer layer and/or the second outer layer and/or the base body can also have fillers, for example abrasive fillers, in particular oxidic or carbide hard fillers.

These hard fillers can be, for example, silicon or silicon carbide, boron, titanium, titanium dioxide, zirconium, quartz and boron nitride.

In preferred embodiments it can be provided that the base body and at least one outer layer, in particular both outer layers, have the same polymer matrix. Although this gives up a little freedom of design, it simplifies the release position of the blade material significantly. The blade material can then be laid out by arranging the respective textile components (i.e. non-woven fabric or foam for the base body and suitable non-woven fabrics or fabrics for the outer layer(s)) on top of one another, and this entire stack then embedded in the polymer matrix in one step. This saves separate embedding for each layer, which massively speeds up the preparation process.

Furthermore, a roller device for a paper, cardboard or printing machine is proposed, the roller device comprising a rotatable roller with a lateral surface and a scraper device for scraping the roller casing. It is provided that the scraper device comprises a scraper blade according to one of the aspects described.

The scraper device can serve to keep the roll surface clean. Alternatively or additionally, the scraper device can also be used to remove the paper or cardboard web from the roller surface. Such roller devices can be used, for example, in the dryer section of a paper machine. In that case, the rotatable roller can be designed as a drying cylinder or a Yankee cylinder. Such roller devices can also be used to advantage when coating or printing paper webs. The scraper blades can, for example, remove excess coating medium (pigment, starch, etc.) or printing ink from the roller. These examples are only intended to illustrate the diverse possible uses of such a roller device. The invention is not limited to these applications.

In advantageous embodiments it can be provided that the lateral surface consists of a metal or a ceramic and has a roughness between Ra=0.4 μm and Ra=1.4 μm.

Alternatively it can be provided that the lateral surface consists of a rubber or epoxy resin, which is filled with oxidic and/or carbide hard materials and has a roughness between Ra=0.05 μm and Ra=2.5 μm, in particular between Ra=0.06 μm and 0.4 μm

If the sharpness of the scraper tip decreases during operation (the contact edge becomes rounded), then fibers and particles from the paper manufacturing process or the printing process come into contact with the scraper and roller. These are set in rotation by the sliding movement of the scraper on the roll surface and hollow out the core of the scraper. To this end, it is advantageous if the first outer layer and/or the second outer layer are more abrasion-resistant than the base body.

The hollowing out reduces the contact surface of the scraper, whereby the scraper pressure - exerted by a suitable scraper holder system - on the scraper tip increases. The scraper tip, especially the outer layers, will now close more quickly and adapt to the roller surface again with the edge now sharpened. This grinding works preferably in combination on hard ceramic or hard-metal roll covers in an Ra range of 0.4 to 1.4 μm, or also on oxidic/carbide hard materials (silicon,

boron, titanium, zirconium, quartz, and boron nitride) filled softer rubber or epoxy resin covers in an Ra range of 0.05 to 2.5μm (preferably 0.06 to 0.4μm). As the grinding process progresses, the contact surface becomes larger again and the contact pressure is evenly distributed again. The cavity under the soft scraper core closes again.

The following are some examples of doctor blades according to various aspects of the invention. The invention is not limited to these examples.

In the examples, a porosity is repeatedly given as a percentage of the base body volume. This porosity, or this proportion of pores, can be determined radiometrically, for example with the aid of a computer tomograph. Alternatively, however, sections of the base body can also be formed, and the proportion of the pore volume of the base body can be determined by determining the proportion of the pore area of the section.

The porosity as well as the fiber content are important parameters of the base body. The continuous regrinding of the scraper blade can be optimized by suitably setting these parameters. It has proven advantageous if the porosity of the plastic matrix is between 2% and 15%, in particular between 4% and 10%.

Alternatively or additionally, it can be provided that plastic fibers, plastic foam, honeycomb or fiber fleece are embedded in the base body. A fiber content (or foam content, etc.) of between 0% by volume and 30% by volume, in particular between 8% by volume and 20% by volume, is advantageous here. Alternatively, the base body can have, for example, between at least 75% by volume, in particular between 75% by volume and 90% by volume, of foam, while the rest of the base body consists of matrix material including filler. Another meaningful parameter is the value tan δ. This is determined for the usual operating temperatures of 30 - 100°C in paper machines by means of dynamic 3-point bending measurement.

For a doctor blade with a first outer layer and/or a second outer layer, the value of tan d can advantageously range between 0.01 and 0.2, in particular between 0.03 and 0.12.

example 1

Doctor blade with two outer layers, each comprising two layers of fiber fabric or fiber fabric consisting of glass, aramid, mineral, carbon fibers, or mixtures of the fibers mentioned per side. The base body is made of plastic fibers, plastic foam, Floneycomb or fiber fleece (glass, aramid, mineral, carbon, polymer fibers or natural fibers) with a fiber content of 8-30% by volume embedded in a plastic matrix with a porosity of 2-15% of the base body volume.

example 2

Example 1, additionally in all layers (outer layers as well as base body) abrasive oxidic/carbide-carbide hard fillers (silicon, boron, titanium, zirconium, quartz and boron nitride)

Example 3

As Example 1 or Example 2, with the two outer layers comprising a layer of +/- 45° woven fabric and a layer of +/- 60° woven fabric per outer layer.

example 4 Two outer layers, each with two layers of +/- 30° to +/- 80° fiber fabric or fiber fabric consisting of glass, aramid, mineral, carbon fibers or mixtures of the above.

Base body with a fiber content of 8 vol%-30 vol% with a porosity in the range of 2 to 10% of the base body volume.

Additionally in all layers (outer layers and base body) abrasive oxidic/carbide hard fillers (silicon, boron, titanium, zirconium, quartz and boron nitride) Example 5

Two outer layers, each with two layers of +/- 30° to +/- 45° fiber fabric or fiber fabric consisting of glass, aramid, mineral, carbon fibers or mixtures of the above.

Base body with a fiber content of 8-30 vol% with a porosity in the range of 2% to 10% of the base body volume.

Additionally in all layers abrasive oxidic/carbide hard fillers (silicon, boron, titanium, quartz, zircon and boron nitride).

Example 6 Two outer layers, each with two layers of +/- 46° to +/- 80° fiber fabric or fiber fabric consisting of glass, aramid, mineral, carbon fibers, or mixtures of the above.

Base body with a fiber content of 8-30 vol% with a porosity in the range of 2% to 10% of the base body volume. Additionally in all layers abrasive oxidic/carbide hard fillers (silicon, boron, titanium, quartz, zircon and boron nitride).

Example 7

As examples 1 to 6, but the two outer layers are made of different materials. (e.g. one layer +/-45° carbon fiber fabric (fabric) and one layer +/- 60° basalt fiber fabric (fabric) per outer layer). example 8

Two outer layers each comprising only one layer of carbon fiber fabric or a bi-, tri- or quadraxial carbon fiber fabric per outer layer. example 9

Two outer layers each comprising a layer +/- 45° carbon fiber fabric per side, base body with a fiber content of 8-30% by volume with a porosity in the range of 2 to 10% of the base body volume. Additionally in all layers abrasive oxidic/carbidic hard fillers (silicon, boron, titanium, zirconium, quartz and boron nitride).

Example 10

Two outer layers, each comprising a layer of +/- 45° carbon fiber fabric on each side, base body with a fiber content of 8-20% by volume with a porosity in the range of 2 to 10% of the base body volume Additionally in all layers abrasive oxidic/carbide hard fillers (silicon, boron , titanium, zircon, quartz and boron nitride).

Example 11

Two outer layers each comprising a layer of +/- 45° carbon fiber fabric on each side, base body with a fiber content of 8-20% by volume with a porosity in the range of 2 to 10% of the base body volume.

In addition, abrasive oxidic/carbide hard fillers (silicon, boron, titanium, zirconium, quartz and boron nitride) only in the outer layers.

Example 12 Two outer layers each comprising a layer +/- 45° carbon fiber fabric or scrim per side, base body with a fiber content of 8-20% by volume with a porosity in the range of 2 to 10% of the base body volume. No use of abrasive oxide/carbide hard fillers. Example 13

Two outer layers each comprising a layer of +/- 45° carbon fiber fabric per side, Compact body with a fiber content of 8-20 vol% and the lowest possible porosity in the range of less than 4% of the body volume. Additionally in all layers abrasive oxidic/carbidic hard fillers (silicon, boron, titanium, zirconium, quartz and boron nitride).

Example 14 A body with a tan d of more than 0.2, where the value for tan d for the entire doctor blade is between 0.01 and 0.20, and in particular where the porosity is also in the range of 2 to 10% of the body volume can. Example 15: Compact base body comprising a non-woven fabric embedded in a polymer matrix (35) with a fiber content of 8-20% by volume, the value for tan d of the scraper blade being between 0.01 and 0.12, and In particular, the porosity can also be in the range from 2 to 10% of the base body volume. Example 16: Body comprising a closed cell foam material embedded in a polymer matrix, the body having a tan d greater than 0.2, wherein for the entire doctor blade the tan d is between 0.01 and 0.20 and in particular the porosity can also be in the range from 2 to 10% of the base body volume.

The invention is explained below with reference to figures. The figures show in detail:

FIG. 1 schematically shows a scraper blade and a section of a roller device according to one aspect of the invention

FIG. 2 shows a section of a scraper blade according to a further aspect of the invention

FIG. 3 shows a scraper blade as is known from the prior art.

FIG. 4 shows a doctor blade according to a further aspect of the invention

FIG. 1 shows a scraper blade 1 which is placed against the outer surface 21 of a rotatable body 20 . The rotatable body 20 can in particular be a roller 20 in a paper, cardboard or printing machine. The scraper blade 2 shown here has a base body 2 which has an end face 4 for contacting the lateral surface 21 and side faces 5, 6 adjoining the longitudinal edges of the end face. A first outer layer 11 is provided on the first side surface 5 and a second outer layer 12 is provided on the second side surface 6 . In alternative versions, only one outer layer, usually the first outer layer 11, can be provided. Depending on the design, a base body 2 and outer layers 11, 12 can be produced separately, and the outer layers 11, 12 can then be attached to the side surfaces 5, 6 of the base body 2. Alternatively, the scraper blade 1 can also be manufactured in one piece. Base body 2 and outer layers 11, 12 then differ in their different structure. In this case, the term side surfaces 5, 6 denotes the boundary between the base body material 2 and the material of the outer layers 11, 12. In the case of doctor blades 1 according to aspects of the present invention, at least the first outer layer 11 comprises a woven fabric or scrim made of reinforcing fibers 30, which in a polymer matrix 35 is embedded, the angle between the reinforcing fibers 30 and the end face 34 being 30° or more, in particular between 45° and 80°, preferably 60°. FIG. 2 schematically shows a section of a scraper blade 1 with a first reinforcing fiber 31 and a second reinforcing fiber 32. The figure is essentially intended to explain the nomenclature of the angles. In current designs, such doctor blades 1 will have a multiplicity of first reinforcing fibers 31 and second reinforcing fibers 32, which are provided in the form of a fabric or scrim in the doctor blade 1 or in an outer layer 11, 12. In FIG. 2, the two reinforcing fibers 30, 31, 32 enclose an angle of size a with the end face 4. The value of a is 30° or more in doctor blades 1 according to various embodiments of the present invention. The negative sign a" indicates that the angle of the second reinforcement fibers 32 is oriented the other way around compared to the angle of the first reinforcement fibers 31 . This type of angle notation allows a simpler and faster comparison of the orientation of different groups of reinforcement fibers 30, 31, 32 to one another.

FIG. 3 shows a scraper blade 1 as is known from the prior art. In the outer layer 11, 12 there are first reinforcing fibers 31 which are essentially orthogonal to the end face 4 and thus to the lateral surface 21, and second reinforcing fibers 32 which are essentially parallel to the end face 4 or lateral surface. These reinforcing fibers 30, 31, 32 are embedded in a polymer matrix 35. If the doctor blade 1 is so worn that one of the second reinforcing fibers 32 is in contact with the rotating lateral surface 21, this fiber 32 is torn out of the doctor blade 1 in a very short time. Small parts of the polymer matrix 35 can usually also break out in this way. However, the orthogonal first reinforcing fibers 31 remain in the scraper blade 1 and then protrude with their tips from the bottom of the blade 1 or the outer layer 11, 12. The result is the saw tap profile 40 indicated as a dashed line in FIG. 3. Until these protruding tips of the first reinforcing fibers 31 have been worn away by comparatively slow wear, the doctor blade 1 does not continuously touch the rotating lateral surface 21, which significantly impairs its effect. In contrast, a doctor blade 1 according to an embodiment of this invention is shown in FIG. In the outer layers 11, 12, in particular the first outer layers, first reinforcing fibers 31 and second reinforcing fibers 31 are also provided in a polymer matrix 35 here. The reinforcing fibers 30, 31, 32 can be introduced as a woven fabric or scrim. As in the prior art, first 31 and second reinforcing fibers 32 can be arranged perpendicular to one another, but they can also assume other angles to one another. It is essential that the reinforcing fibers 30 , 31 , 32 are not arranged parallel to the end face 4 or the lateral surface 21 . In contrast, the reinforcing fibers have an angle of 30° and more. In the example in FIG. 4, the reinforcing fibers 31, 32 are arranged at +45°/−45°, for example. When they come into contact with the rotating lateral surface, these reinforcing fibers 30, 31, 32 can no longer be torn out of the blade, but remain firmly connected to the structure of the scraper blade 1 or the outer layer 11, 12. The formation of a sawtooth 40 is avoided and the scraper blade 1 is in continuous contact with the lateral surface 21 over its entire longitudinal direction L.

Reference List

1 scraper blade

2 basic body 4 face

5 side face

6 side face

11 first outer layer

12 second outer layer 20 rotatable body

21 lateral surface

30 reinforcement fibers

31 first reinforcement fibers

32 second reinforcement fibers 35 polymer matrix

40 saw tooth

L length direction

Claims

patent claims

1. Scraper blade (1) for scraping the lateral surface (21) of a rotatable body (20), the scraper blade (1) comprising:

- a base body (2) which has an end face (4) for contacting the lateral surface (21) and side faces (5, 6) adjoining the longitudinal edges of the end face (4), and

- A first outer layer (11), which is arranged on a first (5) of the two side surfaces (5, 6), characterized in that the first outer layer (11) comprises a woven fabric or scrim made of reinforcing fibers (30, 31, 32). embedded in a polymer matrix (35), the angle between the reinforcing fibers (30, 31, 32) and the end face (4) being 30° or more, in particular from 45° to 80°, preferably 60°.

2. Doctor blade (1) according to one of the preceding claims, characterized in that the doctor blade (1) comprises a second outer layer (33) which is arranged on the second side surface (6) of the base body (2), and the second outer layer ( 33) comprises a woven or scrim made of reinforcing fibers (30, 31, 32), which is embedded in a polymer matrix (35), the angle between the reinforcing fibers (30, 31, 32) and the end face being 30° or more, in particular 45° ° to 80°, preferably 60°.

3. Doctor blade (1) according to one of the preceding claims, characterized in that the reinforcing fibers (30, 31, 32) of the first outer layer (32) and/or the second outer layer (33) are glass fibers, aramid fibers, mineral fibers, carbon fibers, or Combinations thereof are executed.

4. doctor blade (1) according to any one of the preceding claims, characterized in that the first outer layer (11) and / or the second outer layer (12) first reinforcing fibers (31) and second Reinforcement fibers (32), which have different orientations, the first reinforcement fibers (31) with the end face (4) enclose a first angle between 30 ° and 80 °, while the second reinforcement fibers (32) with the end face a second angle between - Include 30° and - 80°.

5. doctor blade (1) according to claim 4, characterized in that the first angle and the second angle are equal in amount.

6. Doctor blade (1) according to one of the preceding claims, characterized in that in the first outer layer (11) and/or the second outer layer (12) there is provided a scrim with first reinforcing fibers (31) and second reinforcing fibers (32), which have an angle of 30° to 85° to the end face (4), in particular -30°/+30°, -45°/+45°, -60°/+60° or -30°/+60° and that a woven fabric or scrim with third and fourth reinforcing fibers (30) is additionally provided, the third and fourth reinforcing fibers (30) having an angle of 0°/90° with respect to the end face (4).

7. Doctor blade (1) according to one of claims 2 to 6, characterized in that the reinforcing fibers (30, 31, 32) of the first outer layers (11) are made of the same material or the same materials as the reinforcing fibers (30 , 31, 32) of the second outer layer (12).

8. doctor blade (1) according to any one of the preceding claims, characterized in that the base body (2) comprises a tangled fiber fleece embedded in a polymer matrix (35), the tangled fibers in particular fibers made of a polymer such as PET, PES, PP , PE or viscose and/or natural fibers such as hemp, flax or cotton or consists of them.

9. Doctor blade (1) according to one of the preceding claims, characterized in that the base body (2) comprises a foam material which is embedded in a polymer matrix (35), the foam material consisting of a natural foam or a plastic foam, in particular a PU or epoxy foam can be formed.

10. Doctor blade (1) according to one of Claims 8 or 9, characterized in that the porosity of the polymer matrix (35) of the base body (2) is between 2% and 15%, while the fiber (or foam) proportion is less than 30 vol% or between 75 vol% and 90 vol%.

11. doctor blade (1) according to one of the preceding claims, characterized in that the value of tan δ of the doctor blade (1) is in the range between 0.01 and 0.2, in particular between 0.03 and 0.12.

12. Doctor blade (1) according to one of the preceding claims, characterized in that the polymer matrix (35) of the first outer layer (11) and/or the second outer layer (12) and/or the base body (2) contains abrasive fillers, in particular oxidic or has carbide hard fillers.

13. Doctor blade (1) according to one of the preceding claims, characterized in that the base body (2) and at least one outer layer (11, 12), in particular both outer layers (11, 12) have the same polymer matrix (35).

14. Roller device for a paper, board or printing machine, the roller device comprising a rotatable roller (20) with a lateral surface (21) and a scraper device for scraping the roller casing (21), characterized in that the scraper device comprises a scraper blade (1) according to any one of the preceding claims.

15. Roller device according to claim 14, characterized in that the lateral surface (21) consists of a metal or a ceramic and has a roughness between Ra=0.4 μm and Ra=1.4 μm, or the lateral surface (21) consists of a rubber or epoxy resin , which is filled with oxidic and/or carbide hard materials and has a roughness between Ra=0.05 μm and Ra=2.5 μm, in particular between Ra=0.06 μm and 0.4 μm.