WO2011042291A1

WO2011042291A1 - Press roll

Info

Publication number: WO2011042291A1
Application number: PCT/EP2010/063775
Authority: WO
Inventors: Sören Köster; Andreas SCHÜTTE; Uwe Matuschczyk; Axel Kratsch; Robert Hilbing; Jörg Leiser
Original assignee: Voith Patent Gmbh
Priority date: 2009-10-07
Filing date: 2010-09-20
Publication date: 2011-04-14
Also published as: DE102009045414A1

Abstract

The invention relates to a press roll for forming a press gap with a counter press element (10) for treating a paper, cardboard, tissue or other fibrous material web (1) in a machine for producing and/or refining the same with a stationary carrier (2) and a revolving roll shell (3), which is supported on the carrier (2) by means of at least one at least partially hydrodynamically lubricated support element (4) that can be pressed against the inside circumferential surface of the roll shell (3). The support element has a support surface (6) that faces the inside circumferential surface of the roll shell (3) and extends in the running direction (5) of the roll shell (3). The support surface comprises at least one oil feeding area, which provides hydrodynamic lubrication during operation and by means of which fresh lubricating oil is fed to the region between the support surface (6) and the inside circumferential surface of the roll shell (3). To this end, the lubrication of the support surface (6) is to be improved in that at least the running surface (7) of the inside circumferential surface of the roll shell (3) passing over the support surface (6) has a plurality of recesses (8).

Description

press roll

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, who over whom The support surface is supported on the carrier by a support element which can be pressed on at least partially hydrodynamically and which has a support surface which faces the inner peripheral surface of the roller jacket and is elongated in the running direction of the roller jacket. which has at least one oil feed point serving for hydrodynamic lubrication during operation, via which fresh lubricating oil is supplied to the region between the support surface and the inner peripheral surface of the roll shell.

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.

In the case of the press roll known from DE 40 40 392 A1, the support surface of the support element for the hydrodynamic lubrication in question is provided in the inlet-side edge region with a groove extending over the entire width of the press zone. In this groove open an additional oil supply serving 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 described in EP 0 345 501. 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 respective, d. H. the hydrodynamic lubrication serving channels 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 in turn due to the aforementioned uneven thickness of the common attributed between supporting element and counterpressure element, in particular counter roller passing elements.

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 in a sufficient manner, the maximum depth of the recesses should be between 0.5 and 100, preferably between 1 and 20 μιτι. In the interest of a comprehensive effect of the wells they should be as evenly 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 compression also leads to a compression of the flexible and compressible roll shell and thus to a diminution 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: FIG. 1 shows a schematic cross section through a press nip;

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

Figures 3a-c: the formation of the lubricant at different

Press Press.

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

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

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

In this case, the at least partially hydrodynamically lubricated lubrication gap 12 is located between the running surface 6 of the support element 4 sweeping running surface 7 of the inner circumferential surface of the roll shell 3 and the support surface. 6

This lubricating gap 12 additional fresh cooled lubricating oil is supplied, for which purpose the support surface 6 may have a plurality of oil supply points.

The supply of additional fresh lubricating oil as a lubricant takes place at least partially independently of a pressure chamber 13 acting on the support element 4.

In the case of a plurality of support elements 4, these can 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 is formed by a press shoe running along the entire press nip with a concave support surface 6. This type of lubrication can be applied to all support elements irrespective of the type of linear power tool (eg long piston, row of cylinders, 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, the running surface 7 of the roll shell 3 has a multiplicity of uniformly distributed, in particular regularly arranged, depressions 8. These have a depth of between 1 and 20 μιτι.

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

As a result, the reinforced area of the roll mantle 3 is substantially less stiffer than the area of the roll mantle 3 forming the tread 7 with the recesses 8. This supports the function of the recesses 8, as will be explained in the embodiment of Figure 3.

The roll mantle 3 is advantageously produced by casting on a cylindrical mandrel, as described for example in EP 469338. The plastic is poured spirally onto the rotating mandrel, wherein the plastic surrounds the reinforcing threads.

To form the recesses 8, the mandrel has corresponding elevations as a negative mold.

The recesses 8 are preferably continuous in the tread 7 and are substantially 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. FIG. 3 shows the change of the lubricant film 12 as a function of the pressing pressure in the press nip. If the pressing pressure does not locally exceed maximum limits, then the lubricant film 12 is maintained over the whole area, ie there is no dry friction between the support 6 and the running surface 7, as shown in FIG. 3a.

If the pressing pressure increases, as shown in FIG. 3b, a boundary region between liquid and dry friction arises. If the pressing pressure exceeds the maximum limit, this results, above all, in compressing the region of the roll shell 3 forming the running surface 7 because of the lower compressive rigidity. Via the associated reduction of the depressions 8, lubricant is forced out of the depressions 8 into the lubricating gap 12, so that as shown in Fig. 3 c, remains sufficiently lubricated.

With decreasing pressure, the wells 8 fill again with lubricant. It is thus ensured even under critical operating conditions such as when passing through batches or paper thickening always an optimal oil supply for generating and maintaining the lubricating film 12. Even with any irregularities occurring uniform lubrication ratios can be achieved across the width of the support member 4 away.

Claims

claims

1 . 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 rotating roll shell (3) which is supported on at least one against the inner peripheral surface of the roll shell (3), at least partially hydrodynamically lubricated support member (4) on the carrier (2) facing one of the inner peripheral surface of the roll shell (3), in the running direction (5) of the roll shell (3) has extended support surface (6) having at least one, during operation hydrodynamic lubrication oil supply point over 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 running surface (7) running over the support surface (6) is at the inside numfangsfläche the roll shell (3) has a plurality of recesses (8).

2. Press roll according to claim 1, characterized in that the maximum depth of the recesses (8) is between 0.5 to 100, preferably between 1 and 20 μιτι.

3. Press roll according to claim 1 or 2, characterized in that the

Recesses (8) are distributed as evenly as possible over the tread.

4. Press roll according to one of the preceding claims, characterized in that the recesses (8) in the running surface (7) form an open area between 2 and 20%, preferably between 5 and 10%.

5. Press roll according to one of the preceding claims, characterized in that the roll shell (3) is flexible.

6. Press roll according to claim 5, characterized in that the support surface (6) is concave to form an extended press nip with a counterpressure element (10) in the form of a cylindrical counter roll.

7. Press roll according to one of the preceding claims, characterized in that the roll shell (3) has a reinforcement (9), in particular a fiber reinforcement.

8. Production of a roll mantle according to one of the preceding claims, characterized in that the roll mantle (3) is formed from plastic which is poured onto the outside of a cylindrical mandrel having the negative shape of the recesses (8).