DE102009045414A1 - press roll - Google Patents

Abstract

The invention relates to a press roll for forming a press nip with a counterpressure element (10) for treating a paper, cardboard, tissue or other fibrous web (1) in a machine for producing and / or finishing the same with a stationary carrier (2) and a circumferential roll shell (3) which is supported on the carrier (2) via at least one at least partially hydrodynamically lubricated support element (4) which can be pressed against the inner circumferential surface of the roll shell (3) and which is one of the inner circumferential surface of the roll shell (3) facing, in Running direction (5) of the roller jacket (3) has an extended support surface (6) which has at least one oil supply point which is used for hydrodynamic lubrication during operation and via which fresh lubricating oil is supplied to the area between the support surface (6) and the inner peripheral surface of the roller jacket (3) becomes. The lubrication of the support surface (6) is to be improved in that at least the running surface (7) of the inner circumferential surface of the roll shell (3) which sweeps over the support surface (6) has a large number of depressions (8).

Description

The invention relates to a press roll for forming a press nip with a counterpressure element for treating a paper, cardboard, tissue or other fibrous web in a machine for producing and / or finishing the same with a stationary support and a rotating roll shell, the at least one be pressed against the inner peripheral surface of the roll shell, at least partially hydrodynamically lubricated support member is supported on the carrier, the one of the inner peripheral surface of the roll shell facing, extended in the running direction of the roll shell support surface which has at least one, during operation taking place hydrodynamic lubrication oil supply point, on the the area between the support surface and inner peripheral surface of the roll shell fresh lubricating oil is supplied.

Such press rolls are used in particular in pressing devices with a so-called extended press zone. Such pressing devices can be used, for example, in press sections for dewatering, but also in smoothing plants for smoothing a fibrous web.

In such a press roll during operation, d. H. in spite of the at least partially hydrodynamic lubrication considerable friction occurs with circumferential roller jacket, which cause sheath wear and which must be compensated by a higher drive power. It has already been proposed, in order to reduce the drive power in the entry region of the press zone, to spray additional oil onto the inner peripheral surface of the roll shell before it enters the press zone.

At the time of the DE 40 40 392 A1 Known press roll, the support surface of the support element for the hydrodynamic lubrication in question in the inlet-side edge region is provided with a groove extending over the entire width of the press zone. In this groove open an additional oil supply channels. The oil supply points formed by the respective channel mouths are connected to each other via the common groove. Thus, the friction losses can already be reduced to some extent. However, if the roll mantle, a felt belt guided through the press zone, the material web to be pressed or the like or the mating surface formed, for example, by a mating roll have irregularities, in particular in the form of thick spots or unevenness, then it must be assumed that the pressure prevails at certain points becomes high that there is little or no oil supplied to the press zone or is retained.

At the points in question, it can also happen that oil is scraped off at the groove. Thus, after lubricating oil is no longer sufficiently taken and drawn into the lubrication gap, the desired hydrodynamic lubricating effect is impaired.

A comparable press roll is also in the EP 0 345 501 described. In this case too, a groove extending transversely across the entire width of the support surface is provided for the hydrodynamic lubrication, into which the relevant channels, ie those serving for the hydrodynamic lubrication, open. This results in the same problems as in the known roller described above.

In addition, in a press roll with hydrodynamic lubrication of the support element, the hydrodynamic support of the roll shell causing lubricant are strongly heated from the inlet side to the outlet side. The degree of heating of the lubricating film is dependent inter alia on its pressure curve and in particular on its gradient and the maximum and on the machine speed. With increasing heating, the viscosity of the lubricating oil is reduced, which reduces its hydraulic capacity or even in certain cases leads to its decomposition.

A particular problem is that at the inlet supplied lubricating oil is not taken sufficiently and fed into the lubrication gap. This is due, inter alia, to the previously mentioned uneven thickness of the elements running together between the support element and the counterpressure element, in particular the counter-roller.

The object of the invention is therefore to ensure a secure lubrication between the support surface and roll shell.

According to the invention, this object is achieved in that at least the running surface sweeping the supporting surface of the inner peripheral surface of the roll shell has a plurality of depressions. These recesses serve as lubricant reservoirs and can aid lubrication when needed.

To ensure this sufficiently, the maximum depth of the recesses should be between 0.5 to 100, preferably between 1 and 20 microns.

In the interest of a comprehensive effect of the wells should this as evenly as possible distributed over the tread and / or arranged as regularly as possible.

It has proven to be advantageous if the recesses in the tread form an open area between 2 and 20%, preferably between 5 and 10%.

Particularly advantageous is the application of the invention in flexible Walzenmänteln. When the regular pressing pressure is exceeded, the lubricant is increasingly displaced from the gap between the support surface and the running surface. However, this pressure increase also leads to a compression of the flexible and compressible roll shell and thus to a reduction of the depressions. In this case, the incompressible lubricant is pressed out of the depressions into the gap between the support and running surface.

This counteracts the dry friction and ensures lubrication safety, especially under impact loads.

This process is reversible due to the elastic properties of the roll shell. When the pressure decreases to the regular pressing pressure, the press shell structure with the recesses forms correspondingly back. The wells are filled with the after-flowing lubricant due to the negative pressure in the same.

The invention also improves the emergency running properties of a failed lubrication system and thus has a positive effect on the life of the roll shell.

Particularly advantageous is the use of the invention in extended press nips, wherein the support surface is formed concave to form the extended press nip with a counterpressure element in the form of a cylindrical counter roll.

To increase the stability and service life, the roll shells generally have a reinforcement, in particular a fiber reinforcement.

The production of the roll shell is advantageously made of plastic, which is poured onto the outside of a cylindrical mandrel, which has the negative shape of the recesses.

The invention will be explained in more detail with reference to an exemplary embodiment. In the attached drawing shows:

1 a schematic cross section through a press nip;

2 : a greatly enlarged partial cross section through the press nip and

3a -C: the formation of the lubricant at different pressing pressures.

In 1 is purely schematically a press roll with a stationary support 2 and a circumferential, flexible roll shell 3 shown. The around the stationary carrier 2 circumferential roller shell 3 is at least one against its inner peripheral surface contactable support element 4 on the carrier 2 supported.

The support element 4 includes one of the inner peripheral surface of the roll shell 3 facing support surface 6 , which is at least partially lubricated hydrodynamically in the present case. The support surface 6 is in the direction of travel 5 of the roll mantle 3 extended to, together with a formed for example by a cylindrical counter-roller counterpressure element 10 to form a so-called extended press zone.

While the fibrous web 1 for smoothing is usually performed solely by such a press nip, it runs for drainage, as shown here, together with a water-absorbing, endless circulating drainage tape 11 usually in the form of a press felt through this.

This is the at least partially hydrodynamically lubricated lubrication gap 12 between the, the support surface 6 of the support element 4 sweeping tread 7 the inner peripheral surface of the roll shell 3 and the support surface 6 ,

This lubrication gap 12 Additional fresh cooled lubricating oil is supplied, including the support surface 6 may have multiple oil supply points.

The supply of additional fresh lubricating oil as a lubricant is at least partially independent of a support element 4 pressurizing pressure chamber 13 ,

In a plurality of support elements 4 they may advantageously be displaceable relative to one another in the radial direction, in order in particular to obtain different pressure profiles.

Here, however, the support element 4 from a press shoe running along the entire press nip with a concave support surface 6 educated.

This type of lubrication can be applied to all support elements regardless of the type of line power generation (eg long piston, piston series, pressure profile adjustment, pressure profile adjustment with flexible pressure bar).

In this case, an at least substantially hydrodynamic lubrication should preferably take place during operation.

To support the lubrication owns the tread 7 of the roll mantle 3 a plurality of evenly distributed, in particular regularly arranged recesses 8th , These have a depth between 1 and 20 microns.

As in 2 shown, have the flexible roll shells 3 made of plastic usually a reinforcement 9 made of fibers, fabrics or as here longitudinally and transversely to the direction 5 extending reinforcing threads.

This causes the reinforced area of the roll mantle 3 much stiffer than the tread 7 with the wells 8th forming region of the roll shell 3 is. This supports the function of the wells 8th as in the design too 3 will be explained.

The production of the roll mantle 3 takes place with advantage by casting on a cylindrical mandrel, as for example in the EP 469338 is described. The plastic is poured spirally onto the rotating mandrel, wherein the plastic surrounds the reinforcing threads.

For the formation of the depressions 8th the mandrel has corresponding elevations as a negative mold.

The wells 8th preferably go continuously into the tread 7 above and are essentially round in plan view.

However, in plan view, they may also have a rectangular, triangular or rhombic shape or even a contour with both rectilinear and curved or rounded boundaries.

3 shows the change of the lubricant film 12 depending on the pressing pressure in the press nip. If the pressing pressure does not exceed the maximum limits locally, the lubricant film remains 12 preserved over the entire surface, ie there is no dry friction between the support 6 and the tread 7 , as in 3a shown.

If the pressure increases, then it changes accordingly 3b a boundary between liquid and dry friction.

If the pressing pressure exceeds the maximum limit, this results, above all, in compressing the running surface because of the lower pressure rigidity 7 forming region of the roll shell 3 , About the associated reduction of the wells 8th Grease from the wells 8th in the lubrication gap 12 pressed, so this, as in 3c shown, remains sufficiently lubricated.

As the pressure decreases, the wells fill 8th again with lubricant. It is therefore always an optimal oil supply for generating and maintaining the lubricating film even under critical operating conditions such as when passing through bales or paper thickening 12 guaranteed. Even with any irregularities that may occur across the width of the support element 4 uniform lubrication conditions are achieved.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• DE 4040392 A1 [0004]
• EP 0345501 [0006]
• EP 469338 [0038]

Claims (8)

Press roll for forming a press nip with a counterpressure element ( 10 ) for treating a paper, board, tissue or other fibrous web ( 1 ) in a machine for producing and / or finishing it with a stationary support ( 2 ) and a circumferential roll shell ( 3 ), which via at least one against the inner peripheral surface of the roll shell ( 3 ) Pressable, at least partially hydrodynamically lubricated support element ( 4 ) on the carrier ( 2 ) is supported, which is one of the inner peripheral surface of the roll shell ( 3 ), in the running direction ( 5 ) of the roll mantle ( 3 ) extended support surface ( 6 ) having at least one oil feed point serving for hydrodynamic lubrication during operation via which the area between the support surface ( 6 ) and inner peripheral surface of the roll shell ( 3 ) fresh lubricating oil is supplied, characterized in that at least the, the support surface ( 6 ) sweeping tread ( 7 ) of the inner peripheral surface of the roll shell ( 3 ) a multitude of depressions ( 8th ) owns. Press roll according to claim 1, characterized in that the maximum depth of the depressions ( 8th ) is between 0.5 to 100, preferably between 1 and 20 microns. Press roll according to claim 1 or 2, characterized in that the depressions ( 8th ) are distributed as evenly as possible over the tread. Press roll according to one of the preceding claims, characterized in that the depressions ( 8th ) in the tread ( 7 ) form an open area between 2 and 20%, preferably between 5 and 10%. Press roll according to one of the preceding claims, characterized in that the roll shell ( 3 ) is flexible. Press roll according to claim 5, characterized in that the support surface ( 6 ) for forming an extended press nip with a counterpressure element ( 10 ) is concave in the form of a cylindrical counter roll. Press roll according to one of the preceding claims, characterized in that the roll shell ( 3 ) a reinforcement ( 9 ), in particular has a fiber reinforcement. Production of a roll mantle according to one of the preceding claims, characterized in that the roll mantle ( 3 ) is formed of plastic, which is poured onto the outside of a cylindrical mandrel, the negative mold of the recesses ( 8th ) having.

Images