EP1753682B1 - Spreader roll - Google Patents

Abstract

A rotary part, in particular a spreader roller for a web-processing machine has a supporting core with a longitudinal axis, said supporting core being mounted at its two longitudinal ends, and having an elastically flexible outer sleeve which surrounds the supporting core in its circumferential direction and extends, in at least some sections, between the two longitudinal ends of the supporting core. The outer sleeve on the supporting core is non-displaceably mounted on at least one bearing and that the outer sleeve is mounted on at least one displacing point at a distance from the bearing so as to be displaceable perpendicular to the longitudinal axis of the supporting core in order for the curvature of the outer sleeve to be adjustable.

Description

The invention relates to a spreader roll for a web-processing machine.

Spreader rolls are used in web-processing machines in order to avoid wrinkling or sagging of the material webs when the webs of material are running. Furthermore, spreader rolls are used to allow side by side juxtaposed material webs to diverge laterally. Parallel juxtaposed webs can be generated, for example, by slitting a wide web of material.

The spreader rollers known from the prior art usually have a bent and stationary core on which a plurality of independent roller segments are supported by means of roller bearings in order to simulate a curved roller in several sections.

The o.g. Spreader rolls are expensive in their construction and maintenance. Furthermore, the o.g. Spreader rolls the curvature not adjustable.

From the US 6,524,227 Furthermore, a spreader roller is known in which the outer casing has in each case one bearing rod attached to each longitudinal end, which is mounted in each case on a so-called double bearing. Due to a lack of connection between the two double bearings, the introduced torque must be absorbed as a torsional moment of the stiffening when bending the spreader roller. This makes a simple attachment to the staging impossible.

The US-A-4,663,809 discloses a roller in which, to compensate for the deflection of the support core, the distance between the roll shell and the support core is adjustable at the roll edge.

From the US-A-4,372,205 is a press roll is known in which a counter-torque is introduced to the roll to compensate for the roll bending by means of a Verstellmechanismusses.

The DE-U-200 05 499 shows nip rolls with an arrangement for bend correction.

The DE-A-199 40 424 further shows a roll with roll core and roll shell, in which the distance between the roll core and shell is adjustable.

Furthermore, in spreader rolls of this type, high forces are exerted on the bearing, which can result in high bearing wear.

It is the object of the present invention to propose an improved rotary part, in particular an improved spreader roller.

The object is achieved with the features of claim 1.

Advantageous embodiments and further developments of the invention are listed in the subclaims.

The invention is based on the idea of creating a spreader roll in which the angle of the deflection as well as the size of the deflection (curvature) can be made independently of the bearing core.

A spreader roll for a web-processing machine, according to the genus has a support core with a longitudinal axis. The support core is mounted here at its two longitudinal ends. Furthermore, the generic spreader roller has an elastically bendable outer jacket, which surrounds the support core in its circumferential direction and which extends at least in sections between the two longitudinal ends of the support core.

In the spreader roll according to the invention, moreover, it is provided that the outer jacket is mounted on the support core on at least one bearing. Here, the outer jacket is mounted on the bearing such that the outer jacket is immovable perpendicular to the longitudinal axis of the support core. Furthermore, the outer jacket is on at least one shift point mounted displaceably perpendicular to the longitudinal axis of the support core, wherein the displacement point is spaced along the longitudinal axis of the support core to the bearing. As a result, the curvature of the outer shell is adjustable. In addition, the outer sheath between the bearing and the displacement point is at least partially elastically deformable.

This makes it possible to bring by relative displacement of outer sheath to support core at the displacement of the outer sheath relative to the support core in a position so that the longitudinal axis of the outer sheath and support core do not coincide at the displacement and coincide on the bearing, the longitudinal axes of the outer sheath and support core. In order to allow a bending of the outer shell between the displacement point and the bearing, the outer sheath is formed at least partially elastically deformable.

As a result, the longitudinal axis of the outer jacket between the bearing and displacement point is curved relative to the longitudinal axis of the support core.

Furthermore, it is provided in the spreader roll according to the invention, that the support core of a foam and / or honeycomb core, which is at least partially covered by a fiber composite material, constructed. In the production of the support core, a foam core with almost unlimited possibility of shaping is first created, which is enveloped by a fiber composite sheath. This creates a support core with a high modulus of elasticity and low weight, which can be realized easily and with almost any shape.

Under a displaceability or immobility perpendicular to the longitudinal axis of the support core is to be understood in this context that the displacement of a Component which is perpendicular to the longitudinal axis of the support core at the displacement point or bearing.

The outer jacket is preferably formed integrally between the bearing and the displacement point.

Unitary is to be understood in this context that the outer shell is formed by a contiguous portion of material (either made of a single cast or of several material sections) and not by a plurality of non-interconnected material sections.

Thus, a spreader roller is provided in which the known from the prior art disadvantages are overcome.

Of course, it is also possible that the outer jacket also has a displacement component parallel to the longitudinal axis of the support core. Thereby, the outer shell can be compressed in its longitudinal direction, whereby a different bending line can be obtained.

According to a preferred embodiment of the invention, two displacement points are provided, between which the bearing is arranged. This makes it possible to bend the outer sheath on both sides of the camp.

According to a preferred embodiment of the invention, it is provided that the outer shell has a respective displacement point at its two longitudinal ends. If the bearing is preferably provided in the middle region of the longitudinal extension of the outer jacket, the outer jacket can be bent symmetrically relative to the bearing.

According to a further preferred embodiment of the outer jacket is rotatably connected to the bearing with the support core, so that the outer shell is rotatably mounted on the support core. The rotatable mounting can be done via rolling or plain bearings. As plain bearings are, for example, hydrodynamic or hydrostatic sliding bearings or air bearings conceivable.

The o.g. Feature is particularly but not exclusively advantageous if the support core is not rotatable about its longitudinal axis.

According to a further preferred embodiment, the outer sheath is rotatably connected to the support core at the first support point. This means that a rigid connection between outer shell and support core is created around a To allow torque transmission between Stützkem and outer sheath and secure the outer sheath against the Stützkem against displacement in the longitudinal direction. The non-rotatable connection between Stützkem and outer jacket is, for example. By gluing or pressing produced.

The o.g. Embodiment is essentially applicable when the Stützkem is rotatable about its longitudinal axis.

A further embodiment of the present invention also provides that at least one support point attached to the outer casing or Stützkem and arranged in the longitudinal direction between the bearing and displacement point is provided, on which at least the curvature of the outer shell of the support core or the outer shell can be brought into abutment. By at least one support point, it is possible to influence the curvature or bending line of the outer shell relative to the Stützkem, as determined by the support point, the minimum distance between the outer shell and Stützkem upon bending of the outer shell. Since upon rotation of the curved outer jacket, regardless of whether the Stützkem on the bearing is rotatably or rotatably connected to the outer shell, in the region of the second support points, a relative movement between Stützkem and outer shell is caused, it is necessary the Stützkem with the outer shell here to rotate together , The rotatable mounting can be done via angle-adjustable rolling or plain bearings.

According to a further preferred embodiment of the invention it is provided that the second support points are arranged in the longitudinal direction on both sides of the bearing and between the two displacement points. Thus, it is possible to set a curvature of the outer shell, which runs symmetrically to the bearing. By supporting the outer shell on a plurality of support points on both sides of the bearing, it is possible to influence the bending line of the outer shell relative to the support core very accurately.

The position of the outer jacket relative to the Stützkem can be accomplished, for example, by two mutually rotatable eccentric discs, which in each case take effect on the arranged at the longitudinal ends displacement points. In this case, a moment is induced by the deflection at the displacement points and the non-displaceable mounting of the outer shell on the support core, which deforms the outer shell according to its bending line relative to the support core. Another possibility of displaceable storage consists of slidable in two levels guides, which can each influence the arranged on the longitudinal ends sliding points. But it is also possible to produce the curvature by a linear displacement and then to pivot the curved spreader roll about the longitudinal axis of the Stützkems.

Confirmation of adjustment can be made hydraulically, pneumatically, electrically or manually.

According to a further preferred embodiment of the invention, the relative adjustment is accomplished by incorporated in the outer tube piezoelectric elements. The incorporated piezoelectric elements may be formed, for example, in the form of piezo fibers. By applying corresponding electrical voltages, the piezoelectric elements stretch and contract at different points of the outer jacket, whereby the outer jacket bends.

There are different ways in which the Stützkem can be formed. According to a further preferred embodiment of the invention, the longitudinal axis of the support core is straight. In a straight Stützkem it is possible that the support core rotates about its own axis as well as that the Stützkem is not rotatable about its own axis.

Another embodiment of the invention further provides that the longitudinal axis of the Stützkems runs curved. In this variant, it is only possible that the Stützkem does not rotate around its own axis and that the rotation of the Outer jacket is realized by rotatable storage in stock.

To optimize the load capacity of the core and to partially determine the curvature, it is advantageous if the support core along its longitudinal axis at least partially changing cross-sectional shape ha, in particular at least partially conical.

In order to keep vibrations of the spreader roller during operation as low as possible, it makes sense if the natural frequency of the support core is as high as possible. Consequently, the modulus of elasticity must be as high as possible and core mass as low as possible. Experiments have shown that natural oscillations in operation can be almost completely suppressed if the support core at least partially made of a material having a modulus of elasticity in the range of 10 to 1000GPa, preferably from 50 to 800GPa, more preferably from 100 to 500GPa and a density in the range of 0.5 to ³ g / cm ³ , preferably from 1.0 to 2.0 g / cm ³ , more preferably from 1.3 to 2.0 g / cm ^{3 is} made.

Preferred materials for the production of the support core are in combination or alone: plastics and / or metallic material which are produced in the form of foams and / or in the form of honeycombs.

According to a further preferred embodiment, the outer shell in its longitudinal direction has a modulus of elasticity in the range from 0.5 to 1000GPa, preferably from 10 to 700GPa, more preferably from 50 to 200GPa, the elastic modulus of the support core being greater than the modulus of elasticity of the outer jacket. Thus, a flexible as possible outer jacket is provided in the longitudinal direction. The lower modulus of elasticity in the longitudinal direction of the support core can be achieved, for example, in that, in the case of a fiber composite material, the fibers are oriented essentially in the circumferential direction of the support core.

So that the circular cross-section of the outer jacket does not experience too much flattening in the case of the web tension and the curvature, it makes sense if the outer casing is as little deformable as possible in the radial direction. Therefore, a preferred embodiment of the invention provides that the outer jacket in the radial direction has a modulus of elasticity which is greater than the elastic modulus in the longitudinal direction.

The influence of the bending line of the outer shell can be influenced by changing the material thickness of the outer shell, so that different bending lines can be adjusted depending on the requirements of the spreader roll. Accordingly, a preferred development of the invention provides that the outer casing has a material thickness and / or cross-sectional shape which changes at least in sections in its longitudinal direction. Other possibilities for influencing the bending line of the outer shell consist of material orientation and / or by the selected material combination.

The outer sheath is preferably produced in combination or solely from a plastic and / or from a metallic material and / or from a fiber composite material.

Furthermore, the outer sheath is at least partially covered by a cover.

In this case, the cover is produced in combination or solely from elastomeric plastic and / or from thermoplastic material and / or from thermosetting plastic and / or from ceramic material.

For property control of the cover, it is advantageous if the composition of the cover material changes continuously and / or discontinuously in the axial direction and / or in the longitudinal direction.

By reference to a continuously changing material composition is meant, for example, a reference having in the radial and / or axial direction a continuously changing material composition, i. a reference material which has no interfaces in its composition as is the case, for example, in reference material in the layer structure. If the covering material has boundary surfaces in its composition, this is called a discontinuous material composition.

By way of example, mention may be made of a cover material which continuously changes its composition in the radial direction from 100% thermoset material to 100% elastomeric material.

By way of example, a reference material may be mentioned, which is constructed from four layers, which are arranged one above the other in the radial direction. It is also possible to choose a construction of one or more layers, for example 2.3.5 or more layers. Here, the first layer is an adhesive layer for connecting the cover to the outer jacket, the second layer is a fiber composite layer, the third layer is an adhesive layer for bonding the second and fourth layers and the fourth layer is a ceramic functional layer.

In the above example, the fiber composite layer is composed of a resin component, a hardener component, a fiber component, and optionally one or more filler components. Here, the resin component epoxy resins, Polyurethane resins, phenol-formaldehyde resins and / or cyanate ester resins. The fiber component may contain, alone or in admixture, fibers of the following types: glass, carbon, aramid, boron, polypropylene, polyester, PPS PEEK, ceramics and / or carbides such as SiC. Filler components may contain carbides, metals or oxides.

Furthermore, it is conceivable that, for example, in the case of a matrix material, the ratio of resin and hardener component changes continuously.

Further, the above embodiment includes that the material composition changes continuously or discontinuously in the longitudinal direction of the reference. This is useful, for example, when edge zones are subjected to greater stress. In this case, then the edge zones can be made of a more wear-resistant material than the other areas.

The surface of a spreader roll has to fulfill different tasks according to the particular application. In order to achieve the best possible spreading effect, the best possible adhesion of the material web should be ensured, which results in the requirement for a rough surface of the cover. To minimize the tendency of the surface of the cover to foul, the surface of the cover should be as smooth as possible. Experiments have shown that best results are achieved when the surface of the cover has a roughness in the range between Ra = 0.001 to 100 μm, preferably Ra = 0.001 to 50 μm, particularly preferably Ra = 0.03 to 20 μm.

According to a further preferred embodiment of the invention, the surface has at least sections of spirally and / or radially arranged grooves and / or through holes and / or blind holes. By this embodiment, for example, grooves for removing air are created. The through holes can be further evacuated.

To drive the spreader roll is either provided that the support core is driven and transmits the torque through the bearing on the non-rotatably connected to the support core outer shell. If the outer casing is rotatably connected to the support core, it makes sense if the outer casing is driven directly by a V-belt or toothed belt or chain or gear drive.

Figur 1

eine erfindungsgemäße Breitstreckwalze im nicht gebogenen Zustand im Querschnitt im Bereich des Lagers und im Bereich einer Abstützstelle sowie im Längsschnitt,

Figur 2

eine erfindungsgemäße Breitstreckwalze im gebogenen Zustand im Querschnitt im Bereich des Lagers und im Bereich einer Abstützstelle sowie im Längsschnitt.

The invention will be further explained with reference to the following schematic and not to scale drawings. Show it

FIG. 1

a spreader roll according to the invention in the non-bent state in cross-section in the region of the bearing and in the region of a support point and in longitudinal section,

FIG. 2

a spreader roll according to the invention in the bent state in cross section in the region of the bearing and in the region of a support point and in longitudinal section.

1 shows a spreader roll 1 according to the invention in the non-bent state in cross-section in the region of the bearing 6 (FIG. 1a) in the region of a displacement point 7 (FIG. Figure 1 c).

The spreader roll 1 has a support core 2 with a longitudinal axis 3. The support core 2 is rotatable about its longitudinal axis 3 extending straight. Here, the Stützkem 2 is rotatably supported in the region of its two longitudinal ends 16 via rolling bearings 15.

The support core 2 is surrounded at least in sections in the direction of its longitudinal axis 3 by an outer jacket 4 with reference 5. The outer shell 4 has a longitudinal axis 8 around which it is rotatable.

The support core 2 is embodied in the present embodiment as a composite body with a foam core 17 and a fiber composite sheath 14 surrounding the foam core.

The outer jacket is formed in the present embodiment as a hollow body.

As can be seen from FIG. 1c, the support core 2 has along its longitudinal axis 3 a changing cross-sectional shape, which tapers on both sides from the section line A-A to the section line B-B.

The outer jacket 4 is made in one piece from a flexurally elastic fiber composite material in the present embodiment.

The cover 5 is constructed in the present embodiment of four layers, which are arranged one above the other in the radial direction. Here, the first layer is an adhesive layer for bonding the cover 5 to the outer jacket 4, the second layer is a fiber composite layer, the third layer is an adhesive layer for bonding the second and fourth layers, and the fourth layer is a ceramic functional layer forming the surface of the cover 5.

In the region of the bearing 6 (FIG. 1 a), the outer jacket 4 is non-rotatably and non-displaceably connected to the support core 2. The rotationally fixed connection is made by an adhesive connection. In the region of the bearing 6, the longitudinal axis 3 of the support core 2 and the longitudinal axis 8 of the outer jacket 4 always fall, i. also in the bent state of the outer shell 4 together. Support core 2 and outer shell 4 are thus rotatable together.

In the region of the displacement point 7, which is arranged in the figure 1b in the region of a longitudinal end of the outer shell 4, the outer jacket 4 is supported via a Rolling 9 on a displaceable perpendicular to the longitudinal axis 3 of the Stützkems 2 bearing 10 from (the arrows in the x and y directions illustrate the possible displacement directions of the bearing 10). The outer shell 4 is thus rotatable relative to the bearing 10 and mounted relative to the support core 2 slidably. In the unbent state of the outer jacket 4, the longitudinal axes 3 and 8 also coincide with the two second support regions 7.

The bearing 10 can be adjusted in this case via two mutually offset by 90 ° Spindelhubgetriebe in the x and y direction. The screw jacks can be driven by stepper motors, which in turn are controlled by an electronic control unit to adjust a variable roll curvature can.

In order to be able to influence the bending line of the outer jacket 4 in the bent state according to the requirements, supporting points 12 pointing in the direction of the support core 2 are arranged on the inner side of the outer jacket 4. The support points 12 set in curved outer shell 4 in contact with the Stützkem 2 the minimum distance between the outer shell 4 and Stützkem 2, whereby the bending line of the outer shell 4 is fixed.

The bearing 6 is arranged centrally in the longitudinal direction of the outer jacket 4. The support regions 12 are arranged on both sides of the bearing 6 in the longitudinal direction of the support core 2.

In the present embodiment, the spreader roller is driven by a drive pulley 18 which is in operative connection with a V-belt (not shown).

FIG. 2 shows the spreader roll 1 according to the invention in the bent state in cross-section in the region of the bearing 6 (FIG. 2a, section line AA in FIG. 2c) and in the region of the displacement point 7 (FIG. 2b, section line BB in FIG. 2c) and in FIG Longitudinal section 8 Figure 2c).

Since in the region of the bearing 6 (FIG. 2 a) the outer jacket 4 is non-rotatably and non-displaceably connected to the support core 2, the relative position between the longitudinal axis 3 and the longitudinal axis 8 does not change in the region of the bearing 6 even in the bent state of the outer jacket 4. The longitudinal axis 3 of the Stützkems 2 and the longitudinal axis 8 of the outer shell 4 coincide in the region of the bearing 6 accordingly.

In the area of the second support point 7, due to the displaceable mounting of the outer jacket 4 relative to the support core 2, the two longitudinal axes 3 and 8 are offset relative to one another by Δx and Δy. The outer shell 4 is thus bent and deflected relative to the support core 2 due to the non-displaceable mounting at the bearing 6 and the displacement by .DELTA.x and .DELTA.y at the second support regions 7. Consequently, the longitudinal axis 8 of the outer jacket 4 is curved relative to the longitudinal axis 3 of the support core 2.

In the bent state of the outer shell 4, the support points 12 come to the support core 2 to the plant and set the bending line of the outer shell 4 relative to the Stützkem 2 firmly. The support points 12 are displaceable in the circumferential direction of the support core 2 relative to the support core 2. Thus, a kind of plain bearing of the support core 2 is formed on the outer jacket 4 at the other second support portions 12. In order to reduce the sliding resistance in the region of the further second support regions 12, it makes sense if the Stützkem 2 is provided at these points with a kind of lubricious coating.

LIST OF REFERENCE NUMBERS

1

Wide push roller

2

supporting core

3

Longitudinal axis (support core)

4

outer sheath

5

reference

6

camp

7

shifting point

8th

Longitudinal axis (outer jacket)

9

Rolling bearings (for outer jacket)

10

movable storage

11

survey

12

support point

13

longitudinal end (outer sheath)

14

Fiber composite shell

15

Rolling bearings (for support core)

16

longitudinal end (supporting core)

17

foam core

18

sheave

Claims (26)

1. Spreader roll (1) for a web-processing machine, having a supporting core (2) with a longitudinal axis (3), which is mounted at its two long ends, and having an elastically flexible outer shell (4), which surrounds the supporting core (2) in its circumferential direction and which, at least in some sections, extends between the two long ends of the supporting core (2), the outer shell (4) being mounted on the supporting core (2) on at least one bearing (6) such that it cannot be displaced, and the outer shell (4) being mounted on at least one displacement point (7) at a distance from the bearing (6) such that it can be displaced in order to permit the curvature of the outer shell (4) to be adjusted at right angles to the longitudinal axis (3) of the supporting core (2), characterized in that the supporting core (2) is constructed from a foam and/or honeycomb core (17) which, at least in some sections, is sheathed in a fibrous composite material (14).
2. Spreader roll according to Claim 1, characterized in that two displacement points (7) are provided, between which the bearing (6) is arranged.
3. Spreader roll according to Claim 2, characterized in that the outer shell (4) has a displacement point (7) at its two long ends (13) in each case.
4. Spreader roll according to one of the preceding claims, characterized in that the outer shell (4) is connected to the supporting core (2) via the bearing (6) such that it can rotate,
5. Spreader roll according to one of the preceding claims, characterized in that the supporting core (2) cannot be rotated about its longitudinal axis (3).
6. Spreader roll according to one of the preceding Claims 1 to 3, characterized in that the outer shell (4) is connected to the supporting core (2) via the bearing (6) such that it cannot rotate with respect thereto.
7. Spreader roll according to Claim 6, characterized in that the supporting core (2) can rotate about its longitudinal axis (3).
8. Spreader roll according to one of the preceding claims, characterized in that at least one supporting point (12) is provided, fixed to the outer shell (4)/supporting core (2) and arranged in the longitudinal direction (3) between bearing (6) and displacement point (7), with which, in the event of curvature of the outer shell (4), the supporting core (2)/outer shell (4) can be brought into contact, at least in some sections.
9. Spreader roll according to Claim 8, characterized in that the supporting points (12) are arranged on both sides of the bearing (6) in the longitudinal direction (3) of the supporting core (2) and between the two displacement points (7).
10. Spreader roll according to one of the preceding claims, characterized in that the relative displacement of the outer shell (4) in relation to the supporting core (2) is brought about by eccentric discs or by guides which can be displaced in two planes and which exert an influence on the displacement points (7).
11. Spreader roll according to one of the preceding Claims 1 to 9, characterized in that the relative displacement is brought about by piezoelectric elements incorporated in the outer shell (4).
12. Spreader roll according to one of the preceding claims, characterized in that the longitudinal axis (3) of the supporting core (2) runs in a straight line.
13. Spreader roll according to one of Claims 1 to 5 and 8 to 11, characterized in that the longitudinal axis (3) of the supporting core (2) runs in a curve.
14. Spreader roll according to one of the preceding claims, characterized in that the supporting core (2) has a cross-sectional shape that changes along its longitudinal axis (3), at least in some sections, in particular in that the supporting core (2) runs conically, at least in some sections.
15. Spreader roll according to one of the preceding claims, characterized in that the supporting core (2) consists of material with a modulus of elasticity in the range from 10 to 1000 GPa, preferably from 50 to 800 GPa, particularly preferably from 100 to 500 GPa, and with a density in the range from 0.5 to 3 g/cm³, preferably from 1.0 to 2.0 g/cm³, particularly preferably from 1.3 to 2.0 g/cm³.
16. Spreader roll according to one of the preceding claims, characterized in that the supporting core (2) is produced in combination or on its own from plastic and/or from a metallic material in the form of foams and/or honeycombs.
17. Spreader roll according to one of the preceding claims, characterized in that, in its longitudinal direction, the outer shell (4) has a modulus of elasticity in the range from 0.5 to 1000 GPa, preferably from 10 to 700 GPa, particularly preferably from 50 to 200 GPa.
18. Spreader roll according to one of the preceding claims, characterized in that, in the radial direction, the outer shell (4) has a modulus of elasticity which is greater than the modulus of elasticity in the longitudinal direction.
19. Spreader roll according to one of the preceding claims, characterized in that, in its longitudinal direction (3), the outer shell (4) has a material thickness and/or cross-sectional shape which changes, at least in some sections.
20. Spreader roll according to one of the preceding claims, characterized in that the outer shell (4) is produced in combination or on its own from plastic and/or from a metallic material and/or from a fibrous composite material.
21. Spreader roll according to one of the preceding claims, characterized in that the outer shell (4) is sheathed in a cover (5), at least in some sections.
22. Spreader roll according to Claim 21, characterized in that the cover (5) is produced in combination or on its own from elastomeric plastic and/or from thermoplastic and/or from thermosetting plastic and/or from ceramic material.
23. Spreader roll according to Claim 22, characterized in that the composition of the material from which the cover (5) is produced is continuous in the axial direction and/or in the longitudinal direction (3) and/or changes discontinuously.
24. Spreader roll according to either of Claims 21 and 22, characterized in that the surface of the cover (5) has a roughness in the range between Ra = 0.001 to 100 µm, preferably Ra = 0.01 to 50 µm, particularly preferably Ra = 0.03 to 20 µm.
25. Spreader roll according to one of Claims 21 to 23, characterized in that, at least in some sections, the surface has grooves arranged spirally and/or radially and/or continuous drilled holes and/or blind drilled holes.
26. Spreader roll according to one of Claims 21 to 23, characterized in that the outer shell is evacuated, at least in some sections.

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