DE212021000470U1 - roller and coating device - Google Patents

Abstract

Roller for a machine for producing or processing a fibrous web, having a roller core and a roller cover attached thereto, which comprises at least one layer made of a rubber-elastic material, which is applied to a base, characterized in that the at least one layer made of rubber-elastic material consists of several windings is made up of extruded material which has an essentially parallelogram-shaped cross-section as well as a bottom, a top and a first side surface and a second side surface, and the windings are arranged next to one another in such a way that the first side surface of one winding meets the second side surface of the adjacent winding is in contact.

Description

The invention relates to a roller for a machine for producing or processing a fibrous web according to the characterizing part of claim 1 and a coating device which includes such a roller.

A large number of rollers are used in plants for the production or processing of fibrous webs. The rollers can support and guide the web, for example a paper web, cardboard web or cellulosic web. Furthermore, various types of rollers are also used to treat fibrous webs.

A large number of these rollers are coated with a rubber-elastic material, in particular rubber.

So describes the Scriptures EP2981647 B1 such a coating unit in the form of a film press with a rubber cover.

Rubber rollers are also used when printing paper or applying paint or adhesives, such as in the DE 20 2011 107 518 U1 described.

The production of such rubber rollers can, as in the DE 20 2011 107 518 described, take place in the so-called roller extrusion process. A roller core - in particular a metal roller core - is guided through the head attachment (so-called cross head) of a rubber extruder. This provides the roll core with a seamless coating of the extruded material. The disadvantage of this method, however, is that the crosshead has to be very specifically adapted to the roll core. The rollers produced in this way have a very high quality and uniform coating. However, the coating of rolls with different diameters requires frequent changing of head attachments and is therefore very time-consuming.

As a possible alternative, the DE 20 2011 107 518 the so-called strip building process. Typically, an extruded rubber strip is applied to a rotating roll core so that the rubber strip is laid down on the roll core in the form of an axial spiral of overlapping rubber strips. The angle of inclination of the laid rubber strips in relation to the roller axis is adjusted by the speed of the axial movement. The advantage of this method is that different thicknesses of the roll cover can be realized with a fixed geometry of the rubber strip by varying the angle of inclination.

However, it has been shown that such rolls produced in strip building occasionally produce markings on the coated fibrous web during operation. Particularly in applications with high quality requirements, this means that these rollers have to be replaced or ground.

It is therefore the object of the present invention to propose a roller which is largely free of markings but can nevertheless be manufactured simply and efficiently.

Finally, another object of the invention is to propose a coating unit for a mark-free coating.

The objects are achieved by a roller according to the characterizing part of claim 1 and a coating device according to claim 11.

Advantageous embodiments are described in the dependent claims.

With regard to the roller, the object is achieved by a 1st roller for a machine for producing or processing a fibrous web, having a roller core and a roller covering attached thereto, which comprises at least one layer made of a rubber-elastic material, which is applied to a base. According to the invention, it is provided that the at least one layer of rubber-elastic material is made up of several windings of extruded material, which has an essentially parallelogram-shaped cross section and a bottom side, a top side as well as a first side surface and a second side surface, and the windings are arranged next to one another in such a way that that in each case the first side face of one turn is in contact with the second side face of the adjacent turn.

In the context of this application, the term "rubber-elastic material" is intended to include elastomers, such as rubber, but also other elastomers such as polyurethanes, in particular a so-called "rollable polyurethane" (millable PU). In addition, however, all types of rubber should be covered by the term “rubber-elastic material”. In particular, so-called hard rubbers, which are counted among the duroplastics.

In order to make the text easier to read, instead of the cumbersome term “all types of rubber and all rubber-elastic materials” consistently uses the more compact formulation “rubber-elastic material”. Unless explicitly stated otherwise, this term should always also include hard rubber materials.

The inventors have recognized that the marking patterns that are generated by the rollers are due to the comparatively low feed rate in the strip building process and to the superimposition of the polymer strips.

In the case of the roller proposed here, there is therefore no need to superimpose the strips at all. At first glance, this appears to be disadvantageous since the thickness of the layer produced is determined by the height (h) of the strand. Thus, only one fixed layer thickness can be produced with a tool, in particular an extruder mouthpiece. However, this disadvantage is compensated for by the improved quality of the coating, which opens up a wider range of possible applications for the roller.

It is therefore particularly advantageous if the underside of the strand material is only in contact with the base.

The base can preferably be the roller core or a layer made of hard rubber or rubber-elastic material.

In advantageous embodiments it can be provided that the underside of the strand material has a width (b) of at least 40 mm, preferably at least 50 mm, particularly preferably between 55 mm and 180 mm in the transverse direction of the roller.

A large width of the strand material offers the advantage that a smaller number of windings is required for the coating of the roll. In this way, the speed of the coating can be increased. However, it has been shown that strand widths that are too large can also be disadvantageous. In order to achieve a roller cover of uniform quality, the rubber-elastic material usually has to be applied a little beyond the two front ends of the roller. This overhang is at least half a strand width and is severed and discarded after the covering has been completed. The wider the strand is selected, the larger this waste is. Therefore, from a certain strand width, the economic advantage of faster application is compensated for by the costs for scrap.

In addition, it is also difficult, especially when producing rolls with a small diameter, to realize a correspondingly large feed for the use of a very wide strand in one revolution.

However, strand widths of up to 180mm have proven to be technically feasible and economically sensible.

Furthermore, it is advantageous if the strand material has a height (h) of more than 4mm, in particular between 5mm and 30mm.

The thickness of the layer applied is determined by the thickness of the strand material, as described. In most cases, layer thicknesses below 4mm do not make sense here. Layer thicknesses in the range between 5mm and 30mm are common and can still be produced stably using strand application.

In general, the strand material can have a width (b) and a height (h), with the width (b) being greater than the height.

Widths that are twice or four times the height or more are particularly preferred.

In principle, the parallelogram-shaped strand can be designed as a rectangular strand. In this case, two adjacent turns abut each other with their perpendicular side surfaces.

However, it will often be helpful if the parallelogram forms an angle (α) between the underside and the first side surface which is less than 90°, for example 85°, 80° or less. In preferred embodiments it can be provided that the angle (α) between the underside and the first side face is in particular between 75° and 55°.

However, the angle (α) is usually more than 45°.

The angle range between 55° and 75° represents an optimum in a certain sense, since angles that are too flat make it more difficult to apply the windings precisely. If the angles are too steep, however, it is not so easy to connect adjacent windings via the side surfaces, since when a force is applied from above to the layer of rubber-elastic material, only a relatively small component of this force acts as a joining pressure in the direction normal to the side surfaces. In the extreme case of α=90°, there is no force component at all perpendicular to the side surface.

The layer of rubber-elastic material can in particular form the only layer or the radially outermost layer of the roll cover.

Depending on the application, the layer of rubber-elastic material can be provided with grooves and/or holes. Such a roll cover is also intended to be covered by this application, even if the individual windings of the cover are no longer parallelograms in the strict mathematical sense due to the grooves or bores.

With regard to the coating device, the object is achieved by a coating device, in particular a film press, or a size press for applying a starch solution to a running fibrous web, the coating device having a treatment nip formed by two transfer rollers. At least one transfer roller, in particular both transfer rollers, is designed as a roller according to one aspect of the invention.

In such coating devices it is particularly advantageous if at least the transfer roller or transfer rollers designed according to one aspect of the invention have a hardness in the range between 12 P&J and 75 P&J (Pusey&Jones), in particular between 20 P&J and 35 P&J.

In addition, it is advantageous in coating devices if the thickness of the roller cover is between 8 mm and 25 mm, preferably between 10 mm and 20 mm, particularly preferably between 12 mm and 17 mm.

With regard to the method, the object is achieved by a method for producing a roller for a machine for producing or processing a fibrous web, the method including the application of a layer of rubber-elastic material to a base, and comprising the steps:

1. a) Providing a base, in particular in the form of a roller core or a layer of rubber-elastic material.
2. b) providing a polymer material, in particular a rubber material in the form of a strand, the strand having a parallelogram-shaped cross section which has a bottom, a top, and a first side surface and a second side surface.
3. c) Laying the strand material onto the base so that the underside is in contact with the base.
4. d) Spiraling of the strand material so that two adjacent windings are in contact with one another exclusively via their side surfaces.
5. e) vulcanizing the applied polymer material to form a rubber-elastic material.

Provision can advantageously be made for the polymer material, in particular rubber material, to be provided in strand form by means of an extruder or a gear pump.

Furthermore, it can be advantageous that in step c) the laying down of the strand material takes place with the application of a contact pressure, which is applied in particular by a contact roller.

The process described above is often followed by a surface treatment. In particular, this can involve grinding the surface in order to achieve sufficient smoothness for subsequent use, e.g. in a coating device.

Typically, suitable surface smoothness after surface treatment is in the range between Ra= 1.0 - 3 µm. Particularly in the case of coating devices, roughness that is too low, e.g. Ra<1 μm, in particular Ra<0.5 μm, can also be disadvantageous.

Alternatively or additionally, the surface treatment can also include drilling or grooving of the roll surface.

In the classic stripbuilding process, the feed rate during grinding often corresponds to or correlates with the feed rate of the extruder. This feed is usually between 5mm and 15mm in the strip building process. However, functional components in a paper machine or coating machine also have similar dimensions. In the event of disturbances in the fibrous web -e.g. With striations of this magnitude, it is often difficult to find out what is causing these disturbances. A roller according to one aspect of the invention, or the associated method, has the additional advantage here that the strand width or the advance during extrusion can be selected in a significantly larger dimension. Thus, this cause of interference in the frequently occurring range of 5-15mm can be excluded, which significantly simplifies troubleshooting.

• 1 zeigt einen Ausschnitt einer Walze, wie sie aus dem Stand der Technik bekannt ist
• 2 zeigt einen Ausschnitt einer Walze gemäß einem Aspekt der vorliegenden Erfindung.
• 3 zeigt einen Ausschnitt einer Walze gemäß einem weiteren Aspekt der vorliegenden Erfindung.

Further advantageous forms of the invention are explained on the basis of exemplary embodiments with reference to the drawings. The features mentioned can not only be advantageously implemented in the combination shown, but can also be combined individually with one another. The figures show in detail:

• 1 shows a section of a roller as is known from the prior art
• 2 shows a section of a roller according to one aspect of the present invention.
• 3 shows a section of a roller according to a further aspect of the present invention.

The term "rubber-elastic material" should also include elastomers in the examples shown in the figures, such as rubber but also other elastomers such as polyurethanes, in particular a so-called "millable polyurethane" (millable PU). In addition, however, all types of rubber should be covered by the term “rubber-elastic material”. In particular, so-called hard rubbers, which are counted among the duroplastics.

1 shows a roll that is manufactured according to the well-known strip-building process. In this case, a layer 2 made of rubber is shown as part of the roll cover on a roll core 1 as a base 1 . This layer 2 is made up of strand material 3, which is deposited on the roll core 1 in a plurality of windings 4.1, 4.2, ... 4.n. Adjacent windings 4.1, 4.2, ... 4.n overlap so that the undersides 6 of the individual windings 4.1, 4.2, ... 4.n partly on the roll core 1 and partly on the neighboring winding 4.1, 4.2, .. .4.n be in touch. In this way, layers 2 are produced, the thickness of which corresponds to a multiple of the height h of the strand material 3 . At the in 1 example shown, the layer height is twice as high as the height h. In other versions, however, three, four or more windings 4.1, 4.2, . . . 4.n can also be superimposed and produce a correspondingly large layer thickness.

2 shows, in contrast, a section of a roller according to one aspect of the present invention. The cross direction in the figure is usually also the axis direction, or cross direction (CD) of the roll.

In this case, a layer 2 made of rubber as part of the roll cover is shown again on a roll core 1 as a base 1 . The strand material 3 is applied in turns 4.1, 4.2. The strand material 3 has a cross section in the form of a parallelogram. The upper side 5 represents the upper side of the layer 2, while the lower side 6 is applied to the base 1 and is only in contact with it. Two adjacent turns 4.1, 4.2 are arranged directly next to each other, so that the first side surface 7.1 of one turn 4.1 is in contact with the second side surface 7.2 of the adjacent turn 4.2. The side faces 7.1, 7.2 of the parallelogram enclose an angle α with the base 1. This angle α is advantageously more than 45°, in particular between 55° and 75°. In principle, an angle of 90° is also possible. However, the angular range between 55° and 75° represents an optimum in a certain sense, since angles that are too flat make it more difficult to apply the windings 4.1, 4.2, . . . 4.n precisely. If the angles are too steep, on the other hand, it is not so easy to connect adjacent windings via the side surfaces 7.1, 7.2, since the side surfaces do not come to lie neatly next to one another when they are placed.

2 shows an advantageous embodiment in which the width b of the underside 6 of the strand material 3 in the axial direction of the roll is greater than the height h.

The width b is often in the range between 50 mm and 180 mm. The height h of the strand material 3 results in the thickness of the layer 2 made of rubber-elastic material, since the turns 4.1, 4.2 do not overlap.

Therefore, the height (h) will usually be more than 4mm, in particular between 5mm and 30mm. If you want to achieve a greater material thickness than 30mm in the roll cover, it may be easier or more sensible in terms of process technology to apply a second layer of rubber-elastic material than to increase the strand height to well over 30mm.

Furthermore, it can be advantageous if the strand material 3 has a width (b) and a height (h), the width (b) being greater, in particular more than twice as great, preferably more than four times as great as the height ( H).

3 shows an embodiment according to a further aspect of the invention. The execution of 3 differs from the in 2 in that the layer 2 made of rubber-elastic material, which forms the radially outermost layer of the roll covering, has grooves 8 and/or bores 8 . These are usually incorporated into the roll cover from the outside according to a specified pattern, eg milled or drilled.

Reference List

1

underlay, roller core

2

layer of rubber

3

strand material

4.1, 4.2,...4.n

coil

5

top

6

bottom

7.1

first face

7.2

second side face

8th

groove, hole

b

Broad

H

Height

(a)

angle

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

• EP 2981647 B1 [0004]
• DE 202011107518 U1 [0005]
• DE 202011107518 [0006, 0007]

Claims (11)

Roller for a machine for producing or processing a fibrous web, having a roller core and a roller cover attached thereto, which comprises at least one layer made of a rubber-elastic material, which is applied to a base, characterized in that the at least one layer made of rubber-elastic material consists of several windings is made up of extruded material which has an essentially parallelogram-shaped cross-section as well as a bottom, a top and a first side surface and a second side surface, and the windings are arranged next to one another in such a way that the first side surface of one winding meets the second side surface of the adjacent winding is in contact. Roller according to one of the preceding claims, characterized in that the underside of the strand material is in contact exclusively with the base. Roller according to one of the preceding claims, characterized in that the rubber-elastic material is rubber. Roller according to one of the preceding claims, characterized in that the base is the roller core or a layer of rubber-elastic material. Roller according to one of the preceding claims, characterized in that the underside of the strand material has a width (b) of at least 40 mm, preferably at least 50 mm, particularly preferably between 55 mm and 180 mm in the transverse direction of the roller. Roller according to one of the preceding claims, characterized in that the strand material has a height (h) of more than 4mm, in particular between 5mm and 30mm. Roller according to one of the preceding claims, characterized in that the strand material has a width (b) and a height (h), the width (b) being larger, in particular more than twice as large, preferably more than four times as large, we the height (h). Roller according to one of the preceding claims, characterized in that the angle (α) between the underside and the first side face is more than 45°, in particular between 75° and 55°. Roller according to one of the preceding claims, characterized in that the layer of rubber-elastic material forms the radially outermost layer of the roller cover. roll down claim 9 , characterized in that the layer of rubber-elastic material has grooves and/or bores. Coating device, in particular film press or size press, for applying a starch solution or coating color to a running fibrous web, the coating device having a treatment nip formed by two transfer rollers, characterized in that at least one transfer roller, in particular both transfer rollers, are designed according to one of the preceding claims.

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