CN113699821B

CN113699821B - Bush roller

Info

Publication number: CN113699821B
Application number: CN202110542751.6A
Authority: CN
Inventors: 维莱·埃罗宁; 塞波·库皮艾宁; A·米蒂宁; T·西洛玛; 约尔马·斯内尔曼; 尤哈·温帕里
Original assignee: Valmet Technologies Oy
Current assignee: Valmet Technologies Oy
Priority date: 2020-05-20
Filing date: 2021-05-19
Publication date: 2024-05-10
Anticipated expiration: 2041-05-19
Also published as: EP3913134A1; CN113699821A

Abstract

A bushing roller (1) comprising: -an axle beam (11) having a journal (13), said journal (13) being supported in a bearing structure (21); a roller head (31) configured to support a belt (41) which is tensioned around an axle beam (11) in the form of a belt loop and is rotatable around the axle beam; a belt (41) rotatable about the axle beam (11) and rotatable relative to the axle beam; and a movable forming element (119) configured to protrude from the axle beam (11) so as to abut against the belt (41) to change the cross-sectional shape of the belt loop.

Description

Bush roller

Technical Field

The present invention relates to a sleeve roller (sleeve roller). Such bushing rolls are typically arranged in the forming section of a fiber web forming machine, such as a paper, board, tissue or pulp machine.

Background

A prior art bushing roller is known, for example, from DE3142045 A1. In this case, a bushing arrangement (SLEEVE ARRANGEMENT) with a fixed sector support shoe/beam is arranged in the forming section of a paper or board machine. The forming section comprises two webs, each forming a closed loop. The two webs are guided such that they run in an adjacent manner along a portion of the bushing arrangement with the sector support shoe/Liang Yuanzhou fixed, forming a fabric wrap (fabric wrap) with the web sandwiched between the webs. Thus, the bushing arrangement with the fixed sector support shoe/beam results in a minimum distance between the two wires, resulting in dewatering of the web between the two wires.

Another forming section is known from document EP2350385B1, which is similar to the forming section in DE3142045 A1, but which comprises a bushing roller with a cross-section of varying radius of curvature. This shape can improve the dewatering pressure caused by the change of the radius of curvature of the liner roll.

Typically, the bushing roller includes a stationary portion, such as an axle beam, for supporting the belt for rotation about the axle beam. The belt is driven by a web that travels around a portion of the bushing roller sliding surface. Therefore, friction problems may occur, in particular, static friction may be generated during start-up, static friction may be generated in a slow travel mode, and sliding friction may be mainly generated in a normal travel mode.

There is a need for a bushing roller that can handle frictional forces in different modes of travel.

Disclosure of Invention

According to the invention, a bushing roller (1) comprises an axle beam (11) with a journal (axle stub, axle end). The journal (13) is supported in a bearing structure (21). Furthermore, the bushing roller comprises a roller head (31) which is configured to support a belt (41) which is tensioned around the axle beam (11) and rotatable around the axle beam in the form of a belt loop. The belt (41) is rotatable about and relative to the axle beam (11). The movable forming element (119) is configured to protrude from the axle beam (11) so as to abut against the belt (41) to change the cross-sectional shape of the belt loop.

Thus, by means of the movable forming element, the shape of the belt loop travelling around the axle beam and corresponding to the circumference of the roller head can be changed to have a protrusion, wherein the movable forming element protrudes. This protrusion can be achieved even during operation of the paper or board machine. Thus, the activation time may be reduced when the movable shaping element is retracted at the time of activation and only after the activation is performed is the protrusion achieved. During start-up of the fiber web forming machine, the forming element is retracted into the interior of the belt circle and the support behind the element rests against the inner surface of the belt. During start-up, all lubrication inlets for the sliding surfaces are in use and the net tension can be reduced. In addition, the peak dewatering pressure and fabric tension can be controlled. The latter allows control of the water removal profile.

Furthermore, such movable forming elements can be easily replaced when they are worn or when the radius of the surface abutting against the belt is to be changed.

Advantageously, the sliding surface (115) may be arranged adjacent to the movable forming element (119) and in front of the movable forming element (119) in the direction of rotation of the belt (41).

Advantageously, the movable forming element (119) can be moved forward and backward in the protruding direction (z).

Thus, the movable shaping element may be in at least two positions, i.e. retracted or protruding. Further, in addition to the above-described advantages, the following advantages are provided.

Advantageously, the forward and backward movement of the movable forming element (119) in the protruding direction (z) can be achieved by means of a piston (1192) housed in a cylinder (1193). The piston (1192) is capable of acting in both directions.

Such an arrangement enables the movable forming element to be set at any protruding position within the stroke of the piston. Thus, any deflection can be compensated for within a minimum range when adjacent movable forming elements are arranged in the axial direction. In other words, the cross-machine direction bending line (of the paper or board machine) may be arranged to differ from the intended bending line by less than 0.25mm/m.

Advantageously, the movable forming element (119) may be supported at the axle beam (11), the support preferably being a hinge (1191) and the forming element of the moving cylinder structure being hinged.

Thus, the rotational forces of the belt acting on the movable forming element and the tension forces from the wire partly surrounding the bushing roller are transferred to the axle beam with a rigid structure without affecting the accuracy in the web forming process. In the case of a movable forming element supported by a hinge, instead of the linear protruding and retracting movement described above, a protruding and retracting movement along a curve is performed. Thus, in combination with the correspondingly varying radii of the top surface of the movable forming element abutting the belt, a smooth adjustment of the protrusion height is achieved while maintaining a low friction between the top surface of the movable forming element and the belt.

When the bushing roller radius exceeds the operating position, the protrusion of the forming element can affect the belt. Therefore, good lubrication must be placed before the forming element to ensure smooth belt slip over the element, tensioning the belt outwards. During start-up, the forming element may retract inside the roller head circle in order to reduce friction.

The projection/outward travel of the forming element beyond the roller head/belt circle may be from 10mm to 120mm, advantageously from 20mm to 70mm. In addition, when the sliding surface may be arranged several millimeters (tens of millimeters) below the head/belt but the radius is the same, the belt may be concave/convex inwardly before shaping the element. This helps reduce the required protrusion/outward travel of the forming elements, which is beneficial for the life of the belt as belt tension and thereby belt wear is reduced.

Thus, significant variations in the parameters of the fabric tensioning wrap (fabric tension wrap) are possible. On the other hand, it is possible to prevent excessive force from the movable forming element to the belt due to friction between the belt and the top surface of the movable forming element, and bending force acting on the support portion of the movable forming element.

Advantageously, in cross section, the surface (1195) of the shaped element (119) abutting against the belt (41) can have a curved convex shape.

Thus, a change in curvature of the shaping element abutting against the top surface of the belt may be applied. Thus, roller deflection (roll deflection) can also be compensated in this way.

Advantageously, the radius of curvature of the curved convex-shaped surface (1195) of the shaping element (119) abutting against the belt (41) can be made smaller in the direction of rotation of the belt.

Thus, the web tension distribution can be controlled in a smooth manner. In addition, the bending of the liner roller can be compensated.

Advantageously, the radius of curvature of the curved shape of the surface (1195) of the shaped element (119) abutting against the belt (41) can be varied continuously or stepwise (stepwise), wherein the number of steps can be 3 to 12.

Since the movable forming element can be easily replaced, different movable forming elements with dedicated top surface shapes can be applied according to the manufacturing process of the paper or paperboard. The material of the forming element may be a metal or a polymer (reinforced composite) or a combination thereof. The manufacturing method may be extrusion, machining, additive manufacturing or casting. Low friction coatings or hard-facing may also be used for sliding surfaces and/or shaped elements that are prone to wear.

Advantageously, the sliding surface (115) may cover a sector of 30 ° to 120 ° of the bushing roller (1).

Since this range corresponds almost to the web wrap, friction caused by the web acting on the belt can be significantly reduced. Furthermore, another sliding surface may be added after the movable forming element in the travelling direction of the belt to support the belt and to reduce friction in case the movable forming element is retracted, for example during start-up of the fiber web forming machine.

Advantageously, the radius of curvature of the sliding surface (115) in cross section may be the same as/constant as the radius of curvature of the roller head (31).

Advantageously, the sliding surface (115) of the sliding element may be surface treated and/or provided with recesses. Furthermore, in the direction of rotation of the belt (41), the lubrication device (1151) may be arranged before the sliding surface (115) and/or through the sliding surface (115). These depressions/recesses/indentations extend in discrete one or more rows along the length of the axle beam. A narrow land area exists between the recesses filled with lubricating oil. The length of the recesses and the number of oil inlet openings per recess may be different.

Thus, the friction coefficient is further reduced.

The invention also relates to a paper or board machine comprising two wires (1015, 1009) in a dewatering or forming section and a bushing roll (1) as described above. The web (1515) on one side of the bush roller (1) abuts the bush roller (1) at the sliding surface (115), thereby transmitting the rotational force to the belt (41) of the bush roller.

Drawings

Hereinafter, a presently preferred embodiment of the present invention will be described based on the drawings, in which:

fig. 1 is a schematic view of a forming section of a paper or board machine employing a bushing roller according to the invention;

FIG. 2 is a perspective view of a bearing structure supporting journals of bushing rolls according to the present invention;

FIG. 3 is a perspective view of an axle beam of a bushing roller according to the present invention;

FIG. 4 is a cross-sectional view along the longitudinal axis (length axes) of a bushing roller according to the invention; and

Fig. 5 is a cross-sectional view perpendicular to the longitudinal axis of a bushing roller according to the invention.

Detailed Description

Fig. 1 shows an example of a schematic structure of a forming section 1000 of a paper or board machine to which a bushing roller 1 according to the invention is applied. Headbox 1001 is used to supply pulp suspension between wires 1009, 1015, which are guided in a closed loop. The wire loop 1015 is guided by the guide rollers 1013, the forming roller 1005 and the liner roller 1. The second web 1009 is guided in another closed loop by guide roller 1007, forming roller 1005 and liner roller 1. Between the forming roll 1005 and the guide roll 1007a, which is dedicated to the guide roll 1007 of the second web 1009, both webs 1015 and 1009 run in parallel to sandwich the web formed thereby.

A forming gap (forming gap) is formed between the two webs 1015 and 1009 at the respective circumferential portions of the forming roller 1005 and the liner roller 1, where the two webs 1015 and 1009 travel along the circumferential portions of the two rollers, with a constant radius fabric tensioning wrap on the forming roller and a varying radius fabric tensioning wrap on the liner roller. Since the webs 1009 and 1015 are slightly elongated in the portions not affected by the rolls, the pressure exerted on the web by the web tension is higher in these fabric tensioning wraps than in the unsupported portions of the web.

The forming gap and fabric tension wrap formed at forming roll 1005 is used to receive pulp suspension from headbox 1001. To provide this tight wrapping at the forming roll 1005, the second wire is guided towards the forming roll by means of a breast roll 1007b arranged close to the forming roll 1005 in such a way that the diffuser section of the headbox 1 is arranged between the forming roll 1005 and the breast roll 1007 b. Thus, a first dewatering of the web is performed at the forming roll 1005.

Another fabric forming wrap is formed at the liner roll 1. Since this description is mainly directed to the liner roller 1, the fabric forming wrap formed at the liner roller 1 will be described as "fabric forming wrap" hereinafter; meanwhile, if desired, the fabric nip (fabric nip) formed at forming roll 1005 will be described as "constant radius fabric stretch wrap" or simply "fabric stretch wrap" (at forming roll 1005).

Furthermore, in the forming section, other means for dewatering the web are arranged, such as dewatering elements 1003 or suction boxes 1011. It will be understood that the above description of the forming section based on fig. 1 is only an example and is not at all limiting the forming section to the mesh arrangement and elements shown in fig. 1 and described above. That is, beside the described elements, further dewatering elements and suction boxes may be provided. Alternatively, one or more of the dewatering elements and/or suction boxes shown may be omitted. Furthermore, different types of web forming concepts may be selected that are suitable for all types of forming machines, headboxes, layouts and webs. Likewise, the function of the liner roll and its location within the forming machine may vary depending on the particular needs of the particular web to be formed.

To form the web, the pulp suspension is fed from headbox 1001 into a forming gap and a constant radius fabric tensioning wrap at forming roll 1005 where the first dewatering takes place. From there, the web is led between the two wires 1015 and 1009 towards the bushing roll 1 and the fabric tensioning wrap. Thus, the web passes through dewatering device 1003, which increases the dryness of the web. In the fabric tensioning wrap, a second dewatering is performed. As described below, with the aid of the bushing roller 1 according to the invention, parameters of the fabric tensioning wrap can be set, such as its length, the pressure it applies, the travel time of the web through the fabric tensioning wrap, etc. Thus, an effective dewatering is performed before the web is further led via suction box 1011 to be taken over and transferred to the next section, such as the press section of a fiber web forming machine.

The bushing roller 1 according to the invention comprises an axle beam 11 and a journal 13. As can be seen from fig. 2, the journal 13 is supported in a base (pedestal) (e.g., a bearing structure) 21. Further, as can be seen from fig. 4, the liner roller 1 includes a roller head 31 that supports a belt 41. The belt 41 is tensioned around the axle beam 11 and rotatable around and relative to the axle beam 11. In particular, the rotation of the belt 41 is caused by the web 1015 being in direct contact with the belt 41 during the common path due to the web tension when passing through the liner roller 1.

Returning to fig. 2, the base 21 comprises an annular flange 25 mounted on the journal 13 in such a way as to be able to transmit torque from the flange 25 to the journal 13.

To provide torque, the flange 25 is connected with a turnbuckle (RIGGING SCREW) 23 by means of a joint 22. That is, one end of turnbuckle 23 is attached to flange 25 by means of joint 22. The other end of turnbuckle 23, opposite to the end attached to the joint, is fixed to base 21. Thus, by turning the turnbuckle 23, the length of the turnbuckle may be lengthened or shortened, thereby causing rotation of the flange 25. The rotation of the flange 25 is transferred to the journal 13, thereby rotating the journal and the axle beam 11 of the bushing roller 1. The flange 25 and the joint 22 form a movement device according to the invention, and the turnbuckle 23 is an example of an actuation device according to the invention.

That is, instead of a turnbuckle, the actuation means may comprise screws, gears, worm gears, hydraulic cylinders or other means adapted to provide a longitudinal movement which is then converted into a rotational movement of the flange 25.

As can be seen from fig. 3, the axle beam 11 is made of a hollow polygonal structure with (in this embodiment eight) rounded corners. Furthermore, the cross section of the axle beam body 111 is symmetrical in different planes, the width of the axle beam 11 (in the y-direction in the figure) being larger than its height (in the z-direction in the figure). The thickness of the plate forming the axle beam body 111 is between 30mm and 60 mm. This geometry of the axle beam has excellent stiffness in its axial direction (the direction of the rotation axis a) while still being able to form the desired cross-sectional shape.

Rounded corners in the sense of the present invention are understood to be those corners comprising arcuate, convex, curved portions having a certain radius of curvature.

The head 113 of the axle beam 11 has a flange-like shape and is provided with a plurality of mounting holes 1131. The head 113 is surrounded by an axle beam body 111, which consists of two curved metal plates 111a, 111 b. The two metal plates 111a, 111b are welded together at their edges to form a hollow body. The edges are arranged parallel to the axis of rotation a of the bush roller 1.

Further, in the axle beam 11, a service opening 117 and other openings are provided to enable access to the interior space of the axle beam 11. Some or all of these openings may be closed with a shutter (hatches).

As can be seen in fig. 4, the journal 13 is mounted to the head 113. The roller head 31 is arranged in a sliding manner on the journal 13. Thus, the roller head 31 can move in the axial direction of the liner roller 1. To achieve this movement of the roller heads 31, hydraulic cylinders (only one of which is shown in fig. 4) 35 are fixed inside the axle beam. The piston rod of each hydraulic cylinder 35 extends through the head 113 of the axle beam 11 and is fixed to the roller head. Accordingly, the roller head 31 can be slidably moved in the direction of the rotation axis a (i.e., leftward and rightward in fig. 4). Thus, on the one hand, the axial position of the roller head 31 can be determined, and on the other hand, the tension of the belt 41 fixed to the roller head 31 and surrounding the axle beam 11 can be adjusted. The plurality of hydraulic cylinders 35 are arranged such that the belt 41 is tensioned by symmetrical tensioning forces.

To accurately determine the position of the roller head 31 and/or prevent excessive stretching of the belt 41, indexing means (indexing means, not shown) are provided to inform the user of the amount of movement of the roller head. In the embodiment, the indexing means shows the distance from the inside (right side in fig. 4) of the base 21 to the roller head 31.

Furthermore, an opening is provided in the roller head 31 through the journal 13. The openings may be closed in a gas-tight manner and used for arranging inlet and outlet pipes for a fluid, such as lubricating oil, for example. Since the opening can be closed in an airtight manner, the pressure inside the belt 41 can be maintained.

As shown in fig. 5, the axle beam has a sliding surface 115. The sliding surface extends in the length direction of the axle beam 11 and is curved in the transverse direction of the axle beam 11. In the embodiment the sliding surface is a separate component mounted to the axle beam 11, but alternatively the sliding surface may be formed integrally with the axle beam 11.

Further, a movable forming element 119 is arranged adjacent to the sliding surface 115 in the axle beam body 111. That is, the forming element is arranged such that the belt 41 passing over the sliding surface 115 thereafter passes over the forming element 119. In cross section, the surface 1195 of the forming element 119 that abuts against the belt 41 has a curved convex shape. The radius of curvature of the curved convex-shaped surface 1195 becomes smaller in the direction of rotation of the belt 41. The radius of curvature of the forming element becomes smaller than the radius of the bushing roller. In this regard, the forming element is movable so that its height protruding from the axle body 111 can be varied. In the axle beam body 111, a pipe system is provided to supply lubrication fluid to the sliding surface 115.

Since the movable forming element 119 is configured to protrude from the axle beam 11, it abuts against the belt 41 rotating around the axle beam 11. By varying the protruding height of the forming element 119, the cross-sectional shape of the loop formed by the strip 41 is varied.

For the purpose of the projection or retraction, the movable shaping element 119 is moved forward and backward in its projection direction z. This is achieved by means of a piston 1192 accommodated in a cylinder 1193. The piston 1192 can function in two directions. Thus, the movable shaping element can be made to protrude to a desired height. When exceeding the radius of the bushing roller in the operating position, the protrusion of the forming element can affect the belt. Therefore, good lubrication must be placed before the forming element to ensure smooth belt slip over the element, thereby tensioning the belt outwards. On activation, the forming element may be retracted inside the roller head circle in order to reduce friction.

The projection/outward travel of the forming element beyond the roller head/belt circle (the imaginary shape of the belt cross section, which is circular unless it is guided in a different way) may be 10mm-120mm, advantageously 20mm-70mm. In fig. 5, the belt circle is denoted by 41a and drawn by a broken line. In addition, when the sliding surface is arranged several millimeters (tens of millimeters) below the head/belt but the radius is the same, the belt may be concave/convex inwardly before shaping the element. This helps reduce the outward travel required, thereby facilitating belt life.

The movable forming element 119 is supported at the axle beam 11 by means of a hinge 1191. Thus, the position of the movable shaping element 119 can not only be changed in a linear manner, but also be tilted. Advantageously, the moving means of the articulated forming element can also be tilted/articulated.

In the direction of travel of the belt 41, the sliding surface 115 is arranged in front of the movable forming element 119. The radius of curvature of the sliding surface 115 in cross section is the same as the radius of curvature of the liner roller/roller head 31. Furthermore, the sliding surface is surface-treated, and preferably may be provided with depressions, such as pits. In addition, in the rotation direction of the belt 41, a lubrication device 1151 is arranged before the sliding surface 115. Thus, the coefficient of friction of the sliding surface 115 may be significantly reduced, causing the belt 41 to run smoothly on the sliding surface 115 before it reaches the movable forming element 119.

It will be appreciated that the cross-sectional shape of the liner roll 1 may vary depending on the requirements of the web being formed, due to the movable forming element 119. Furthermore, these changes may be performed while the paper or board machine is running. In addition, it is possible to vary not only the cross section of the bushing roller 1, but also the rotational position of the movable forming element by rotating the journal 13 via the turnbuckle 23 and the flange 25. Thus, the change of the fabric tension wrapping parameters can be achieved in a variety of ways, which results in improved dewatering and forming of the web. Reference numeral 116 denotes additional slide elements, one of which is arranged behind the movable shaping element 119.

In addition, fig. 4 and 5 show tubes 110, 112, 114 for supplying and discharging (see arrows in the tube in fig. 4) lubricant. The supply and discharge are performed via holes in the journal 13. Furthermore, these tubes are supported in the interior of the axle beam 11. The main drain 120 is for the returning lubricant, which needs to be cooled and filtered before being re-fed to the bushing rollers. In addition to the lubricant supply lines, smaller hydraulic lines are shown, such as those indicated by 118, 118a, 118 b. These hydraulic tubes 118, 118a, 118b, described later, are used to actuate the piston 1192. The connection to the hydraulic actuator, the lubricant collector device and the lubricant supply/injection tube is performed by means of a steel reinforced hose to allow thermal movements and bending.

Although the present invention has been described based on the presently preferred embodiments thereof, the scope of the present invention is not limited to the foregoing description and drawings, but is defined by the claims.

Thus, the embodiment may be changed. For example, the described cross-sectional shape need not be provided for the entire axle beam body, but only a portion of the axle beam body may have a polygonal cross-section. One or more other portions may have different cross-sections.

The polygonal cross-section may have six to twelve corners or corresponding angles. Although it is preferred to round the corners, such a chamfer is not explicitly necessary, for example, in the case where the metal plate is not bent but a plurality of metal strips are welded together to form an axle beam body.

Additionally, at least a portion of the axle beam body may have a circular cross-section.

Instead of a continuous change, the radius of curvature of the curved shape of the surface of the forming element abutting against the belt may be changed stepwise. The number of stepwise steps may be 3 to 12.

Although a certain range of wrapping is not mentioned above, the sliding surface may cover a sector of 30 ° to 120 ° of the bushing roller, so that a web with a common wrap on the bushing roller may drive the belt with the help of the supporting sliding surface.

Although in an embodiment the lubrication means is arranged before the sliding surface in the direction of rotation of the belt, alternatively or additionally the lubrication means may be provided by the sliding surface. The arrangement of the lubrication means depends on the assembly before the sliding surface is formed.

Although polygonal structures are described in the cross-section of the axle beam, in some cases other more complex dimensional shapes may be used, such as cross-sections of T-beams, Y-beams, or X-beams.

Claims

1. A bushing roller (1) comprising:

-an axle beam (11) having a journal (13), said journal (13) being supported in a bearing structure (21);

-a roller head (31) configured to support a belt (41) which is tensioned around the axle beam (11) in the form of a belt loop and which is rotatable around the axle beam (11);

-said belt (41) being rotatable about and relative to said axle beam (11); and

A movable forming element (119) configured to protrude from the axle beam (11) so as to abut against the belt (41) to change the cross-sectional shape of the belt loop,

Wherein the movable forming element (119) is supported at the axle beam (11), the support being a hinge (1191),

The surface of the movable shaping element abutting against the belt has a curved convex shape, and the radius of curvature of the curved convex shape surface becomes smaller in the direction of rotation of the belt, the shaping element performing a protruding and retracting movement along a curve, so that the height of its protrusion from the axle beam can be changed.

2. Bushing roller (1) according to claim 1, wherein

A sliding surface (115) is arranged adjacent to the movable forming element (119) and in front of the movable forming element in the direction of rotation of the belt (41).

3. Bushing roller (1) according to claim 1 or 2, wherein

The movable forming element (119) is movable forward and backward in the protruding direction (z).

4. A bushing roller (1) according to claim 3, wherein

The forward and backward movement of the movable forming element (119) in the protruding direction (z) is achieved by means of a piston (1192) housed in a cylinder (1193), said piston (1192) being capable of functioning in both directions.

5. Bushing roller (1) according to claim 1 or 2, wherein

When viewing the section of the belt (41), the stroke of the movable forming element (119) protruding from the circumference of the roller head is in the range of 10mm-120 mm.

6. Bushing roller (1) according to claim 1 or 2, wherein

When viewing the section of the belt (41), the stroke of the movable forming element (119) protruding from the circumference of the roller head is in the range of 20mm-70 mm.

7. Bushing roller (1) according to claim 1, wherein the radius of curvature of the curved shape of the abutment of the movable forming element (119) against the surface (1195) of the belt (41) changes continuously or stepwise, wherein the stepwise progression is 3 to 12.

8. Bushing roller (1) according to claim 2, wherein

The sliding surface (115) covers a sector of 30 ° to 120 ° of the bushing roller (1).

9. Bushing roller (1) according to claim 2 or 8, wherein

The sliding surface (115) has a radius of curvature in cross section that is the same as the radius of curvature of the roller head (31).

10. Bushing roller (1) according to claim 2 or 8, wherein

The sliding surface (115) of the sliding element is surface treated and/or has recesses.

11. Bushing roller (1) according to claim 2 or 8, wherein

In the direction of rotation of the belt (41), lubrication means (1151) are arranged before the sliding surface (115) and/or through the sliding surface (115).

12. A paper or board machine comprising in a dewatering section:

two webs (1015, 1009), and

The bushing roller (1) according to any of claims 2 to 11,

Wherein the web on one side of the bushing roller (1) abuts the bushing roller (1) at the sliding surface (115) transmitting a rotational force to the belt (41) of the bushing roller.