DE102021133212A1 - scraper and coating device - Google Patents

Abstract

Scraper, in particular edge scraper, for cleaning a moving surface and coating device of a machine for producing or processing a fibrous web, the scraper having a scraper body on which the scraper can be attached to a holding device, and a scraper tip for contacting the moving surface, characterized in that at least one supply line for a lubricating fluid is provided in or on the scraper, the at least one supply line ending in a distributor for distributing the lubricating fluid over the length of the scraper, and the distributor being open at the tip of the scraper so that the lubricating fluid can escape .

Description

The invention relates to a scraper, in particular an edge scraper, for cleaning a moving surface of a machine for producing or processing a fibrous web according to the preamble of claim 1, and a coating device, in particular a film press according to the preamble of claim 10.

A large number of different rollers are used in the production or processing of fibrous webs such as paper or cardboard webs. Many of these rollers continuously become dirty during operation and need to be cleaned or replaced.

A particular example are coating devices for indirectly coating the fibrous webs, such as the so-called film presses.
A thin film of an application medium, for example a starch solution, is pre-metered onto a transfer roller, which is then transferred to the fibrous web in a transfer nip. However, since the fibrous web usually has different widths depending on the type produced, the problem arises that the width of the film pre-metered onto the roller must be adaptable to the width of the material web.
For this purpose, the use of so-called edge scrapers is known from the prior art. Such scrapers are positioned at the edges of the transfer roller, where they scrape off the applied medium. These scrapers are movably attached, which means that the device can be adapted to a changed web width. Such edge scrapers are, for example, in the writings DE102004039162 A1 or CH 712,248.

Furthermore, it is from the prior art like that DE202017101177 U1 known to provide a blowing or spraying device to keep the scraper and its surroundings clean, or to achieve a lubricating effect.

Recently, however, there has been a trend to replace traditional rubber rollers with rollers having a polyurethane surface in film presses and similar devices. Polyurethane is more sensitive to a lack of scraper lubrication than rubber. Together with the ever-increasing operating speeds of the film presses, this means that the lubrication of the scrapers by the spraying devices is often insufficient and the roll surfaces are damaged.

It is therefore the object of the present invention to propose a scraper which overcomes the difficulties of the prior art.
In particular, it is an object of the invention to provide improved lubrication of a doctor, especially an edge doctor, for a coating device.
In addition, it is an object of the invention to keep resource consumption low when deploying and using the scraper.

These objects are completely solved by a scraper according to the characterizing part of claim 1, and a coating device according to the characterizing part of claim 10.

Further advantageous embodiments of the present invention can be found in the dependent claims.
With regard to the scraper, the object is achieved by a scraper, in particular an edge scraper, for cleaning a moving surface of a machine for producing or processing a fibrous web, the scraper having a scraper body on which the scraper can be attached to a holding device, and a scraper tip for Contacting the moving surface. According to the invention, at least one supply line for a lubricating fluid is provided in or on the scraper, the at least one supply line ending in a distributor for distributing the lubricating fluid over the length of the scraper,
and wherein the distributor is open at the scraper tip so that the lubricating fluid can escape.

The lubricating fluid can in particular be lubricating water.

The moving surface is usually the surface of a roller, such as a transfer roller. Alternatively, the moving surface can also be a belt, e.g. a transfer belt or press belt. The invention is not limited to use on a specific surface.

The fibrous web can be, in particular, a paper web, cardboard web, cellulosic web or else a nonwoven web.

In contrast to the prior art, scrapers according to one aspect of the invention provide for the lubricating fluid to be guided through at least one feed line that either runs entirely or partially inside the scraper itself, or is attached entirely or partially directly to the outside of the scraper.
This supply line ends in a distributor for Distributing the lubricating fluid over the length of the scraper. This serves to distribute the lubricating fluid evenly over the length of the scraper, and thus to ensure even lubrication
This distributor is open at the tip of the scraper in such a way that the lubricating fluid can exit there over the entire width of the scraper or at least essentially over the entire width of the scraper. An area to which no lubricating fluid is distributed or from which no lubricating fluid escapes can optionally be provided only in the edge area of the scraper. This can be advantageous, for example, in order to prevent lubricating fluid from escaping laterally beyond the moving surface.

The invention makes it possible for the lubricating fluid to be applied directly to the tip of the scraper, which comes into contact with the surface. Sufficient lubrication of the scraper can thus be achieved very easily.
While with the known spray nozzles a large part of the lubricating water ends up unused in the environment, with scrapers according to aspects of the present invention the entire lubricating fluid is used for lubricating. In this way, a considerable amount of lubricating water can be saved during operation of the system, which not only offers economic advantages, but is also desirable for ecological reasons.

In advantageous embodiments, it can also be provided that several supply lines for a lubricating fluid are provided in or on the scraper, which end in the distributor and which are distributed, preferably evenly distributed, in particular over the length of the scraper.
For example, it can be provided that the feed lines are arranged at a distance of 5 cm, 8 cm or 10 cm from each other.
This wording is intended to include in particular those designs in which only one common supply line is provided in the area of the scraper body, which is then divided into several lines, which then end with the described distances in the distributor.

It can advantageously be provided that the distributor comprises or consists of a distribution groove which extends in the longitudinal direction of the scraper and is open at the tip of the scraper. It is advantageous in such an embodiment that this distribution groove can be manufactured very simply in terms of manufacturing technology.

In a simple design, the distributor consists only of this distributor groove. The lubricating fluid is then directed from the one or more supply lines into the distribution groove. From there, the fluid can fill up the distribution groove and is thus distributed over the length of the scraper.

The scraper can then be placed against the moving surface, for example, in such a way that the open side of the groove is directed towards the surface, so that the lubricating fluid can escape to the surface.

Alternatively, it can be provided that the distribution groove is completely or partially filled with a porous material, in particular a porous ceramic material or a polymer foam. Such a material allows for an even distribution of the fluid along the length as well as an even delivery of the lubricating fluid onto the surface. In particular, it can be provided that the porous material is in contact with the moving surface when the scraper is used as intended.
In addition, such a material can be advantageous since the scraper tip, which is rather thin in any case, is further weakened by the introduction of the groove. By completely or partially filling this groove, the scraper tip receives additional reinforcement.

In alternative designs, however, the distributor can also be realized in a different way, without using a distribution groove. For example, when using appropriate methods of 3D printing (“additive manufacturing”), transverse distributions can be provided inside the scraper, from which openings then lead to the tip of the scraper. More complex structures are also possible.

In a particularly advantageous embodiment, the scraper can be of modular design. On the one hand, a base module can be provided, which makes the scraper body available, and a wear module, which includes the scraper tip. The base module and the wear module are detachably connected to one another.
Such a scraper is usually only used in the machine until the scraper tip is worn to such an extent that an adequate cleaning effect can no longer be achieved. Then the entire scraper is discarded. However, the scraper body can still be used further.

Such a modular division of the scraper has the advantage that instead of the entire scraper, only the wearing module has to be exchanged and disposed of, while the base module can remain in the machine longer.
The wear module can advantageously be a maximum of 50% of the scraper height,

in particular less than 30%, preferably 20% or less of the scraper height. With an exemplary height of the scraper of 75 mm, for example, it may be sufficient to design the wear module with a height of 15 mm. As a result, only around a fifth of the waste is generated when changing.
The modules can, for example, be connected to one another in a non-positive or positive manner. Simple screw connections are often useful.

This modular design of the scraper is particularly advantageous in combination with designs in which only one common supply line is provided in the area of the scraper body, which is then divided into several lines, which then end with the described distances in the distributor.
In this case, the routing of the lines is advantageously carried out in such a way that the division into a plurality of lines takes place on the wear module. Thus, when changing the wear module, only one line connection, namely that of the common supply line, has to be ensured.
The base module can be constructed entirely or at least partially from a metal. Alternatively or additionally, the wear module can be constructed at least partially from a polymer material and/or a ceramic.
The dimensions of the doctor are characterized by its length (in the cross-machine direction -CD), its height and its thickness.

Doctors in accordance with embodiments of this invention can extend the entire CD direction of the machine, being up to 10m or more in length. When used as edge scrapers, however, lengths of less than 1m are common. In particular, it can be provided that the scraper has a length of between 5 cm and 40 cm, in particular between 10 cm and 30 cm.

In exemplary embodiments, the height of the scraper can be between 50 mm and 200 mm, in particular between 75 mm and 150 mm.

In contrast, the thickness of the scraper, in particular of the scraper tip, is significantly less, although scrapers according to various embodiments of this invention can also be thicker than conventional scrapers. Despite this, the thickness of the scrapers is generally less than 10 mm, in particular 5 mm or less.

With regard to the device, the object is achieved by a coating device, in particular a film press for indirectly applying a liquid or pasty medium to a running fibrous web, the coating device comprising at least one transfer roller for transferring the liquid or pasty medium to the material web. According to the invention, it is provided that the coating device has at least one scraper for cleaning the transfer roller, which scraper is designed according to one aspect of the invention.

In particular, it can be provided that the coating device has an edge scraper on a drive-side and a guide-side edge of the transfer roller, the two edge scrapers being designed according to one aspect of the invention.

The scrapers, in particular the edge scrapers, can be designed either as dragging scrapers or as piercing scrapers. Both variants are possible within the scope of the invention.

Thanks to the improved lubrication, it is now also easier for the surface of the transfer roller to be made entirely or partially of a polyurethane.

However, scrapers according to aspects of the invention can also be used for surfaces or transfer rollers made of other materials, for example rubber materials, metal surfaces or composite materials.

Various options are conceivable for regulating or controlling the quantity of lubricating fluid that is supplied to the scraper. It can be provided that a common valve device is provided, which controls the amount of fluid for both edge scrapers, or that each edge scraper is assigned its own valve device for controlling the amount of fluid. While the solution with a valve device is more economical and is completely sufficient given the usually similar contamination situation on the driver and drive side, the variant with separate valve devices allows the lubricating fluid to be released in a more targeted manner.

• Satz 1: Schaber, insbesondere Randschaber, zur Reinigung einer bewegten Oberfläche einer Maschine zur Herstellung oder Verarbeitung einer Faserstoffbahn, wobei der Schaber einen Schaberkörper aufweist, an dem der Schaber an einer Haltevorrichtung befestigbar ist, sowie eine Schaberspitze zum Kontaktieren der bewegten Oberfläche, wobei der Schaber modular aufgebaut ist und ein Basismodul aufweist, das den Schaberkörper zur Verfügung stellt und der Schaber weiterhin ein Verschleißmodul aufweist, welches die Schaberspitze umfasst, wobei das Basismodul und das Verschleißmodul lösbar miteinander verbunden sind.
• Satz 2: Schaber nach Satz 1, wobei das Basismodul aus ganz oder teilweise aus Metall gefertigt ist, während das Verschleißmodul zumindest teilweise aus einem Polymermaterial und/oder einer Keramik aufgebaut ist.
• Satz 3: Schaber nach einem der Sätze 1 oder 2, wobei das Verschleißmodul maximal 50% der Schaberhöhe (H), insbesondere weniger als 30%, bevorzugt 20% oder weniger der Schaberhöhe (H) ausmacht.
• Satz 4: Schaber nach einem der vorherigen Sätze, wobei der Schaber eine Länge zwischen 5 cm und 40cm, insbesondere zwischen 10cm und 30cm aufweist.
• Satz 5: Schaber nach einem der vorherigen Sätze, wobei das Basismodul und das Verschleißmodul kraftschlüssig und/oder formschlüssig miteinander verbunden sind, insbesondere mittels einer oder mehrerer Schraubverbindungen miteinander verbunden sind.
• Satz 6: Beschichtungsvorrichtung, insbesondere Filmpresse zum indirekten Auftrag eines flüssigen oder pastösen Mediums auf eine laufende Faserstoffbahn, wobei die Beschichtungsvorrichtung zumindest eine Übertragungswalze zum Übertragen des flüssigen oder pastösen Mediums auf die Materialbahn umfasst, dadurch gekennzeichnet, dass die Beschichtungsvorrichtung zumindest einen Schaber zum Reinigen der Übertragungswalze aufweist, welcher gemäß einem der Sätze 1 bis 5 ausgeführt ist.
• Satz 7: Beschichtungsvorrichtung gemäß Satz 6, dadurch gekennzeichnet, dass die Beschichtungsvorrichtung an einem triebseitigen und einem führerseitigen Rand der Übertragungswalze (10) jeweils einen Randschaber (1) aufweist, wobei die beiden Randschaber (1) gemäß einem der Sätze 1 bis 5 ausgeführt sind.

Incidentally, the modular construction of the scraper from a base module and a wear module represents an inventive idea in itself, independently of the elements of lubrication. This inventive idea can be described in the following sentences, whereby the designations and definitions used up to now continue to be used :

• Set 1: scrapers, in particular edge scrapers, for cleaning a moving surface of a machine for the production or processing of a fibrous web, the scraper having a scraper body on which the scraper can be attached to a holding device, and a scraper tip for contacting the moving surface, wherein the scraper is modular and has a base module that provides the scraper body and the scraper further has a wear module that includes the scraper tip, the base module and the wear module being releasably connected to each other.
• Sentence 2: Scraper according to sentence 1, wherein the base module is made entirely or partially of metal, while the wear module is at least partially constructed of a polymer material and/or a ceramic.
• Set 3: scraper according to one of sets 1 or 2, wherein the wear modulus makes up a maximum of 50% of the scraper height (H), in particular less than 30%, preferably 20% or less of the scraper height (H).
• Set 4: scraper according to one of the previous sentences, wherein the scraper has a length between 5 cm and 40 cm, in particular between 10 cm and 30 cm.
• Sentence 5: Scraper according to one of the preceding sentences, wherein the base module and the wear module are connected to one another in a non-positive and/or positive manner, in particular are connected to one another by means of one or more screw connections.
• Sentence 6: Coating device, in particular a film press for indirect application of a liquid or pasty medium to a running fibrous web, the coating device comprising at least one transfer roller for transferring the liquid or pasty medium to the material web, characterized in that the coating device has at least one scraper for cleaning the Has transfer roller, which is carried out according to one of the sentences 1 to 5.
• Set 7: Coating device according to Set 6, characterized in that the coating device has an edge scraper (1) on a drive-side and a driver-side edge of the transfer roller (10), the two edge scrapers (1) being designed according to one of sentences 1 to 5 .

• 1 zeigt schematisch einen Schnitt durch einen Schaber gemäß einem Aspekt der Erfindung
• 2 zeigt die Draufsicht einer Schaberspitze gemäß einem weiteren Aspekt der Erfindung
• 3a bis 3e zeigen jeweils Schaberspitzen gemäß verschiedenen Aspekten der Erfindung
• 4 zeigt schematisch einen Schnitt durch einen Schaber gemäß einer weiteren erfinderischen Idee

The invention is explained below with reference to figures. The invention is not limited to the embodiments shown here. The figures show in detail:

• 1 shows schematically a section through a scraper according to an aspect of the invention
• 2 Figure 12 shows the plan view of a scraper tip according to a further aspect of the invention
• 3a until 3e each show scraper tips according to various aspects of the invention
• 4 shows schematically a section through a scraper according to a further inventive idea

1 Figure 1 shows a scraper 1 according to an aspect of the invention. The scraper tip 3 is intended to be placed against a moving surface 10 . The scraper body 2 can be attached to a scraper holder, eg clamped. The height H of such a scraper 1 can be between 5 cm and 15 cm, for example.
In the embodiment shown here, a feed line 4 is provided, which runs entirely inside the scraper 1 . Alternatively, the feed line 4 can also run entirely or partially outside of the scraper 1 . The supply line 4 ends in a distributor 5 which can distribute the lubricating fluid over the length L of the scraper 1. In this example, the distributor 5 is designed as a distribution groove 5 that extends in the longitudinal direction L of the scraper 1 . The distribution groove 5 is open at the scraper tip 3 to allow the lubricating fluid to exit.
the inside 1 shown scraper 1 is modular. It includes a base module 7 and a wear module 8. The wear module 8 includes the scraper tip 3, which is exposed to continuous wear during operation of the scraper 1. If the scraper 1 can no longer perform its task adequately due to this wear, the entire scraper 1 normally has to be replaced. Due to the modular design, it is now sufficient to simply replace the wear module 8, while the base module 7 can continue to be used. The base module 7 can be made of metal, for example, while the wearing module 8 can be made entirely or partially of plastic.

In 2 shows the top view of a scraper tip 3, as is used, for example, in a scraper as in 1 can be used. Two supply lines 4 are provided over the length L of the scraper 1 here, the ends 6 of which open into a distributor 5 . Particularly in the case of longer scrapers 1, more than two supply lines 4 can also be provided. The distributor 5 is again designed as a distributor groove 5 . When using such a distribution groove 5, it is generally advantageous if the longitudinal ends of this distribution groove 5, as in 2 shown, are closed to prevent leakage of the lubricating fluid.
At the in 2 scraper 1 shown, the distribution groove 5 is considered in the thickness direction D of the scraper 1, not attached in the middle. Instead, the in Running direction LR of the moving surface 10 viewed front wall 9a made thinner than the rear wall 9b. This can be advantageous since the lubricating effect of the lubricating fluid in the rear part of the scraper tip 3 is significantly higher than in the front part, which can lead to insufficient lubrication there if the front walls 9a are too thick.

The 3a until 3e 12 show various alternative embodiments of a scraper tip 3 according to various aspects of the invention. This is intended to make it clear that a large number of embodiments are possible for scraper 1 according to aspects of the invention. However, the invention is not limited to these versions.

3a shows a scraper tip 3 as in 2 shown. The scraper tip 3 rests against a running surface 10, such as the transfer roller 10 of a film press.

In 3b is the top 3 of the 3a supplemented by the fact that the distributor 5 is designed in the form of a distributor groove 5 which is completely or at least partially filled with a porous material 11 . This porous material 11 can be in the form of a ceramic or a plastic foam, for example, and improves the even distribution of the cleaning fluid in the longitudinal direction of the scraper. In addition, the porous material 11 stabilizes the scraper tip 3. Since the front wall 9a is designed to be comparatively thin, it can form a weak point. This can be avoided with the help of the porous material 11 . The execution of 3c differs from the 3a in that the front wall 9a is realized in the form of a lip 12. This can be made of a different material than the scraper 3 or the wear module 8 and be attached to it. The lip 12 then only serves to prevent the lubricating fluid from escaping against the running direction LR of the surface 10 and has almost no cleaning effect. In this case, for example, the lip 12 can then be designed in such a way that it wears out in a targeted manner during a break-in period until it is in precise and sealing contact with the surface 10 at the predetermined scraper position.

3d 1 shows an alternative embodiment in which the distributor 5 is not designed as a distribution groove but as an internal distribution channel 5: the lubricating fluid is routed from this distribution channel 5 via a large number of channels or also via a slot to one or more outlet openings 13. Such internal structures can be reliably produced, in particular by means of 3D printing processes, even with more complex geometries.

3e finally shows a variant of the scraper tip 3 from 3b . Here the distributor 5 is also designed as a distribution groove 5 which is filled with a porous material 11 . However, the opening of the groove is not directed towards the running surface 10 here. Instead, the groove is skewed and the opening 13 is just before the first point of contact of the scraper tip 3 with the surface 10. This embodiment has no front wall 9a, thereby avoiding a possible weak point. In alternative embodiments, the porous material 11 can therefore also be dispensed with.

4 shows a scraper 1 according to a further inventive idea. the inside 4 shown scraper 1 is modular. It comprises a base module 7 and a wear module 8. The base module 7 makes the scraper body 2 available, on which the scraper 1 can be fastened to a holding device.
The scraper tip 3 is intended to be placed against a moving surface 10 .
The wear module 8 includes the scraper tip 3, which is exposed to continuous wear during operation of the scraper 1. If the scraper 1 can no longer perform its task adequately due to this wear, the entire scraper 1 normally has to be replaced. Due to the modular design, it is now sufficient to simply replace the wear module 8, while the base module 7 can continue to be used. The base module 7 can be made of metal, for example, while the wearing module 8 can be made entirely or partially of plastic.
At the in 4 Scraper 1 shown, the base module 7 and the wear module 8 are connected in an exemplary form-fitting manner by means of a dovetail connection. However, a large number of other connection options are also conceivable here, e.g. screw connections etc.
In the embodiment shown here, the scraper 1 has no means for guiding, distributing or dispensing fluid.
Such a scraper 1 can, for example, also be used with conventional lubricating devices, eg lubricating spray pipes, etc. Depending on the application, use without additional lubrication is also possible in principle. The height H of such a scraper 1 can be between 5 cm and 15 cm, for example.

Reference List

1

scraper

2

scraper body

3

scraper tip

4

supply line

5

distributor

6

end of the supply line

7

base module

8th

wear module

9a

front wall

9b

back wall

10

moving surface

11

porous material

12

lip

13

exit port

D

thickness of the scraper

H

scraper height

L

scraper length

LR

direction of the surface

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102004039162 A1 [0003]
• DE 202017101177 U1 [0004]

Claims (13)

Scraper (1), in particular edge scraper (1), for cleaning a moving surface (10) of a machine for producing or processing a fibrous web, the scraper (1) having a scraper body (2) on which the scraper (1) at a holding device can be fastened, and a scraper tip (3) for contacting the moving surface (10), characterized in that at least one supply line (4) for a lubricating fluid is provided in or on the scraper (1), the at least one supply line (4 ) terminating in a distributor (5) for distributing the lubricating fluid over the length (L) of the scraper (1), and wherein the distributor (5) is open at the scraper tip (3) so that the lubricating fluid can escape. scraper (1) after claim 1 , characterized in that several supply lines (4) for a lubricating fluid are provided in or on the scraper (1), which end in the distributor (5) and which are distributed in particular over the length (L) of the scraper (1). are evenly distributed. Scraper (1) according to one of the preceding claims, characterized in that the distributor (5) comprises a distribution groove which extends in the longitudinal direction (L) of the scraper (1) and is open at the scraper tip (3). scraper (1) after claim 3 , characterized in that the distribution groove is completely or partially filled with a porous material (11), in particular a porous ceramic material. scraper (1) after claim 4 , characterized in that the porous material (11) is in contact with the moving surface (10) when the scraper (1) is used as intended. Scraper (1) according to one of the preceding claims, characterized in that the scraper (1) is of modular design and has a base module (7) which makes the scraper body (2) available and the scraper (1) also has a wear module (8) comprising the scraper tip (3), the base module (7) and the wear module (8) being detachably connected to one another. scraper (1) after claim 6 , characterized in that the base module (7) is made entirely or partially of metal, while the wear module (8) is at least partially constructed of a polymer material and / or a ceramic. Scraper (1) after one of Claims 6 or 7 , characterized in that the wear module (8) makes up a maximum of 50% of the scraper height (H), in particular less than 30%, preferably 20% or less of the scraper height (H). Scraper (1) according to one of the preceding claims, characterized in that the scraper (1) has a length (L) of between 5 cm and 40 cm, in particular between 10 cm and 30 cm. Coating device, in particular a film press for indirect application of a liquid or pasty medium to a running fibrous web, the coating device comprising at least one transfer roller (10) for transferring the liquid or pasty medium to the material web, characterized in that the coating device has at least one scraper (1) for cleaning the transfer roller (10), which according to one of Claims 1 until 9 is executed. Coating device according to claim 10 , characterized in that the coating device on a drive-side and a driver-side edge of the transfer roller (10) each having an edge scraper (1), the two edge scraper (1) according to one of Claims 1 - 9 are executed. Coating device according to claim 11 , characterized in that a common valve device is provided, which controls the fluid quantity for both edge scrapers (1), or that each edge scraper (1) is assigned its own valve device for controlling the fluid quantity. Coating device according to one of Claims 10 until 12 , characterized in that the surface (10) of the transfer roller is constructed entirely or partially from a polyurethane.

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