EP0777012B1 - Pressure roll - Google Patents

Abstract

A press roller has a stationary carrier (12) and a revolving cover (14) which is supported over its internal circumferential surface (16) by at least one compressible lubricated support element (18) on the carrier. The element has a surface (20) facing the cover's inner surface and extended in the cover's travel direction and several points (22) from which fresh lubrication oil is fed between the surfaces. The oil feed is achieved at least partly independently of the pressure chamber (19) acting on the support element. The support surface has at least one row (Ri) of such oil feed points extending in the direction of the roller axis, each point including a drill-hole (26) near which is a constriction.

Description

The invention relates to a press roll with a stationary Carrier and a circumferential roller shell, which at least one against the inner peripheral surface of the roll shell compressible, at least partially hydrodynamically lubricated Support element is supported on the carrier, the one of the inner peripheral surface facing the roll shell, in the running direction of the roll shell has an extended support surface, which several Has oil supply points over the area between Support surface and inner peripheral surface of the roll shell fresh lubricating oil is supplied, the supply being fresh Lubricating oil at least partially independent of that Supporting pressure chamber takes place.

Such press rolls (see WO-A-93/13263) are used in particular in press devices used with a so-called extended press zone. Such pressing devices can, for example, in press sections, but also used in calibration and smoothing plants Find.

With such a press roller, i.e. with rotating roller jacket despite the at least partially hydrodynamic lubrication significant friction occur which cause coat wear and which is caused by a higher drive power must be compensated. It was although already proposed to reduce drive power Additional oil in the entry area of the press zone sprayed onto the inner circumferential surface of the roll shell, before it enters the press zone. To reduce the Frictional losses have also already been proposed, the support surface of the support element in the inlet-side edge area one extending over the entire width of the press zone Slot. This eliminates the friction losses already reduce to a certain extent. Know however, the roll shell, one led through the press zone Felt tape, the web of material to be pressed or the like or the counter surface formed, for example, by a counter roller Irregularities, especially in the form of thick spots or unevenness, it must be expected that that at certain points the pressure becomes so high that there little or no more oil is added to the press zone will or will be preserved. At the relevant points it can also happen that oil is wiped off at the slot becomes.

In a press roll known from DE 40 40 392 A1 are mentioned in a in the support surface of the Support element formed, essentially over the entire Pocket extending width of the press zone several grooves provided, into which each lubricant channels open. At In one embodiment, there are three grooves in the pocket provided, two of which lie one behind the other in the direction of the roller axis. With such an arrangement it is true possible when commissioning the press arrangement for to provide hydrostatic support for the roll shell, while this is hydrodynamic at normal rotational speed is supported. However, here too it cannot be ruled out be that due to irregularities both in the roll jacket, in a felt belt led through the press zone, as well as in particular by a counter roller or with the counter surface formed with the strip-like rolled product or with the band-like rolled product places higher pressure occur where the oil supply decreases or is even interrupted.

In addition, that with a press roll with hydrodynamic Lubrication of the support element the hydrodynamic support of the roll jacket causing lubricant from the inlet side be heated to the outlet side. The degree of Heating of the lubricating film is one of them Pressure curve and in particular its gradient and the maximum as well as the machine speed. With increasing warming the viscosity of the Lubricating oil less, what its hydraulic carrying capacity reduces or even in certain cases to its decomposition leads. It also gets with increasing machine speed more difficult to read the hot oil film adhering to the coat sufficient cooling in one pass through the lubrication gap or to renew. The main problem is that the lubricating oil supplied at the inlet is insufficient Dimensions taken along and drawn into the lubrication gap. This is, among other things, due to the aforementioned unequal thickness of the joint between the support element and Elements that pass through the counter roller.

Large differences in thickness often lead to wedging between support element and counter roller, in the recessed pocket, causing destruction. To be noted is also that in a hydrodynamically generated lubrication gap the thickness of the lubricating film at the point with the amount greatest negative ratio of the local pressure gradient to the local viscosity is lowest. This The location is in the usual press zones in the area of Press zone outlet, where there is a negative with falling pressure Value results.

The invention has for its object a press roll to create the type mentioned in the case of different Operating conditions always an optimal supply guaranteed with fresh cool lubricating oil and a Temperature distribution as uniform as possible over the support surface of the support element is ensured.

The object is achieved according to the invention in that the Support surface at least one in the direction of the roller axis extending row of a plurality of separate, at least partially independent of the support element pressurized pressure chamber fed oil supply points has, each comprising a bore in the area, preferably throttling occurs inside, preferably the oil supply points each through a local depression of the support surface and one in this depression opening throttling bore are formed and wherein webs are provided between the depressions, their surfaces at least essentially at the same level like the rest of the support surface.

Because of this training it is achieved that a uniform Even then, supply with fresh, cool lubricating oil is guaranteed if in places an increased pressure due to irregularities in the roll shell, one passed through the press zone felt tape or the like the material web to be treated, in particular paper or Cardboard, or that formed, for example, by a counter roller Counter surface occurs. Such an uninterrupted The supply of fresh, cool lubricating oil is therefore particularly important also guaranteed where, for example, scraps of paper and folding or thickening of the fibrous web to be treated pass through the press zone. While cross currents through the webs of lubricating oil are practically excluded through the holes designed with throttle characteristics ensures that the lubricating oil when a local, underload occurring especially in peripheral areas, a gap opening, not excessively escaping and thus the supply of the press points under overload not lost. Because of this mutual Separation of the large number of oil supply points of each Row and the at least partially from the pressure room for the Independent support element and thus a sufficiently high Pressure-generating feed can cause local irregularities can be easily compensated. This is practical excluded that local irregularities the supply of fresh, cooled pressure oil temporarily or reduce or interrupt permanently. The oil supply is higher, especially at the critical points concerned Press loads fully guaranteed, which also the desired temperature distribution as uniform as possible becomes. The press roll according to the invention is therefore advantageous can also be used in particular with such pressing devices, those with a regular passage of scraps of paper or folds or fiber thickening through the press zone must be expected. The same problem always occurs also at the edge of the product web where the web thickness abruptly ends.

The respective row of oil supply points is preferred at least one distributor channel formed in the support element assigned via which several oil supply points together with fresh lubricating oil. There can also be several Distribution channels one behind the other in the direction of the roller axis be provided. The holes can be at least partially individually connected to the distribution channel and / or at least partially grouped together and in groups be connected to this distribution channel.

Means are preferably provided for the values for pressure and / or amount of fresh lubricating oil supplied individual and / or groups of holes to be set separately. It is the easiest way to do that Press roll as required for different operating conditions adapt.

The supply of a respective row of oil supply points can completely independent of the one acting on the support element Pressure space or partially done via this pressure space. With a combined lubrication with oil over the Contact pressure for the pressure element supplying the support element and additional oil supplied would be in the event of a failure of the additional Oil supply always good emergency lubrication through given the oil over the pressure chamber. This type of lubrication can with all support elements regardless of the type of Line force generation (e.g. long piston, piston series, pressure profile adjustment, Pressure profile setting with flexible pressure bar and the like) can be applied.

The supply of fresh lubricating oil along a number of oil supply points is advantageously carried out alternately independently from the pressure chamber acting on the support element and via the pressure chamber acting on the support element.

It is also conceivable that in addition to the at least one Row of a variety of separate, at least oil supply points fed partly independently of the pressure chamber at least one parallel row from a plurality from independent, fed via the pressure chamber Oil supply points is provided. In this case, Direction of rotation of the roll shell alternately one row one kind and a parallel series of the other kind be provided. Different rows of one each Variety of separate, at least partially oil supply points fed independently of the pressure chamber preferably separately from each other with fresh lubricating oil provided.

The possibility of optimal adaptation to different Operating conditions are particularly given if the pressure values for the at least partially independent of Oil supply points fed by a row and / or the pressure values for the at least partially independent of Oil supply points of different rows fed from the pressure chamber can be set separately. For a variable setting different pressure profiles are also radial against each other sliding support elements conceivable. In this case it is expedient to have adjacent support elements without gaps to seal against each other.

Particularly with a view to optimally distributing the temperature it is beneficial to have several, each other parallel rows of a large number of each other separate, at least partially independent of the pressure chamber to be supplied with supplied oil supply points, the oil supply points two adjacent rows transverse to the direction of the Roll jacket preferably offset from one another, i.e. on Gap are arranged.

In particular with regard to the desired, if possible Even temperature distribution is also an advantage, though at least one row from a plurality of separate, at least partially fed independently of the pressure chamber Oil supply points in the running direction of the roller shell considered in the range between 1/4 to 3/4, preferably 1/2 is arranged to 3/4 of the support surface.

Figur 1

eine schematische, teilweise geschnittene Darstellung eines Teils einer Preßwalze,

Figur 2

eine Draufsicht auf einen Teil des Stützelements der in Figur 1 gezeigten Preßwalze, wobei der Walzenmantel weggelassen ist,

Figur 3

einen Schnitt durch einen Teil des in Figur 2 gezeigten Stützelements entlang der Reihe von Ölzufuhrstellen,

Figur 4

eine schematische Querschnittsdarstellung einer der der Figur 1 vergleichbaren Preßwalze, wobei jedoch eine über den Druckraum gespeiste Ölzufuhrstelle dargestellt ist,

Figur 5

eine schematische, perspektivische Teildarstellung eines mit zwei Reihen von Ölzufuhrstellen versehenen Stützelements,

Figur 6

eine schematische Darstellung eines Ausführungsbeispiels einer Ölzufuhrstelle,

Figur 7

eine schematische Darstellung eines weiteren Ausführungsbeispiels einer Ölzufuhrstelle und

Figur 8

eine Figur 3 vergleichbare Darstellung, wobei die den Ölzufuhrstellen zugeordneten Vertiefungen genauer dargestellt sind.

Further advantageous embodiment variants of the press roll according to the invention are specified in the subclaims. The invention is explained below using exemplary embodiments with reference to the drawing; in this show:

Figure 1

1 shows a schematic, partially sectioned illustration of a part of a press roll,

Figure 2

2 shows a plan view of a part of the support element of the press roll shown in FIG. 1, the roll jacket being omitted,

Figure 3

3 shows a section through part of the support element shown in FIG. 2 along the row of oil supply points,

Figure 4

2 shows a schematic cross-sectional representation of a press roll comparable to FIG. 1, but showing an oil feed point fed via the pressure chamber,

Figure 5

2 shows a schematic, perspective partial illustration of a support element provided with two rows of oil supply points,

Figure 6

1 shows a schematic illustration of an exemplary embodiment of an oil supply point,

Figure 7

is a schematic representation of another embodiment of an oil supply point and

Figure 8

a Figure 3 comparable representation, the recesses assigned to the oil supply points are shown in more detail.

In Figures 1 and 4 is a press roll purely schematically 10 with a stationary support 12 and a rotating roller shell 14 shown. The around the stationary carrier 12th revolving roll shell 14 is against at least one its inner peripheral surface 16 can be pressed on support element 18 Supported support 12.

The support element 18 includes one of the inner peripheral surface 16 of the roll shell 14 facing support surface 20, the present Case at least partially lubricated hydrodynamically becomes. The support surface 20 is in the running direction LW of the roll shell 14 extended to along with one example a so-called counter surface formed by a counter roller to form an extended press zone.

The one formed between the roll shell 14 and the support surface 20 Lubrication gap which is at least partially hydrodynamic lubricated press roll 10 becomes additional fresh chilled Lubricating oil supplied, for which the support surface 20 several oil supply points 22 (see also FIGS. 2, 3 and 5 till 9). Additional fresh lubricating oil is supplied the support element 18 is at least partially independent of one pressure chamber 19.

With a plurality of support elements, these can advantageously slidable in the radial direction relative to each other be, in particular to different pressure profiles receive. In principle, the support element is also conceivable 18 at least in groups while maintaining the desired relative mobility without gap against each other to seal.

The oil supply points 22 are arranged in rows here, with at least one row R _i extending in the direction of the roller axis _and consisting of a plurality of separate oil supply points 22 which are fed at least partially independently of the pressure chamber being provided in the support surface 20 (compare in particular FIGS. 2, 3, 5 and 6). The oil supply points 22 are preferably each formed by a local depression 24 in the support surface 20 and a capillary-like bore 26 opening into this depression 24. Webs 28 are provided between the depressions 24, the surfaces of which are preferably at least substantially at the same level as the rest of the support surface, ie are not themselves lowered.

In the exemplary embodiments shown in FIGS. 2 to 4 is only one such row of oil supply points 22 intended. In contrast, contain those shown in Figures 1 and 5 Variants two such series. It can however, a different number, especially a larger number be provided by rows. It is also conceivable that rows of oil supply points only over part the width of the support member 18 and adjacent Rows are arranged so that one over the other and the other extends across the other part of the width.

A respective row R _i of oil supply points 22 can be assigned at least one distributor channel 30, preferably formed in the support element 18 (cf. FIG. 1).

Via such a distribution channel 30, which preferably extends generally in the direction of the roller axis, a plurality of oil supply points 22 are supplied together with fresh, cool lubricating oil. In the simplest case, a single distribution channel 30 can be assigned to a respective row R _i of oil supply points. However, it is also conceivable to provide several distributor channels 30 one behind the other in the direction of the roller axis for each row R _i . Basically, oil can be supplied from one side or from two sides. The oil distributor can, for example, be cylindrical or conical or also have a stepped cross section. Finally, the cross section of the inlet opening or the sum of the cross sections of the inlet openings of the distribution channel 30 is advantageously larger than the sum of all cross sections of the bores 26 connected to this channel.

In a practically preferred embodiment, the Bores 26 each have a diameter in the range of approximately 0.3 mm to 3 mm preferably 1 mm. The length of this Bores 26 is preferably about 5 to 100 mm, preferably 5 to 50 mm. Instead of a capillary-like formation the holes are basically also other types the throttling conceivable.

It is also necessary that the oil pressure in the area of the inlet openings of the holes 26 larger than the pressure in Lubricating film 34 over the support surface 20 of the support element 18 is.

The holes 26 can at least partially individually with the Distribution channel 30 may be connected. According to Figure 3, the However, holes 26 are at least partially combined into groups and connected in groups to the distribution channel 30 his. In the embodiment shown in Figure 3 the holes 26 are combined in pairs and via a feed line 33 common to the respective pair connected to the distribution channel 30.

In addition, means 36, in particular valves, throttles or the like may be provided to the values for pressure and / or amount of fresh lubricating oil supplied individual and / or groups of holes 26 separately adjust. In the embodiment variant according to FIG Such a valve 36 is inserted into the feed lines 33. In principle, however, it is also conceivable, at least individual bores 26 individual control and regulating means assign.

With regard to a respective row R _i of oil supply points 22, the supply of freshly cooled lubricating oil can take place completely independently of the pressure chamber 19 acting on the support element 18 or also partially via this pressure chamber 19. FIG. 4 shows an oil supply point 22, the bore 26 of which opens directly into the pressure chamber 19 acting on the support element 18. In contrast, in the exemplary embodiment shown in FIG. 3, the feed lines 36 are connected to the distribution channel 30, which is supplied with freshly cooled lubricating oil from the outside, ie independently of the pressure chamber 19 acting on the support element 18.

Instead of externally feeding all oil supply points 22 of a respective row R _i , it is also possible, for example, to supply fresh lubricating oil along the row R _i alternately independently of the pressure chamber 19 and via the pressure chamber 19. Adjacent oil supply points 22 of a respective row are accordingly fed differently.

Furthermore, in addition to at least one row R _i from a plurality of separate oil supply points which are at least partially independent of the pressure chamber, at least one parallel row from a plurality of oil supply points which are in turn separate from one another but are supplied via the pressure chamber can be provided. In this case, the rows R _{i are} preferably arranged in such a way that in the running direction LW of the roll shell 14 preferably one row R _i alternately each from a plurality of separate oil supply points 22 fed at least partially independently of the pressure space and a row R _i parallel to this from a plurality of Oil supply points 22 that are independent of one another and are supplied via the pressure chamber are provided.

Such a combined lubrication with an oil supply accommodates both via the pressure chamber and from the outside the other advantage that in the event of a possible Failure of the additional oil supply is still a sufficient one Emergency lubrication ensured via the pressure chamber is. This type of lubrication can be used with all support elements regardless of the type of line force generation (e.g. long piston, Piston row, pressure profile adjustment, pressure profile adjustment with flexible pressure bar) can be used.

In the case of a plurality of rows R _i , each consisting of a plurality of separate oil supply points 22, which are at least partially independent of the pressure chamber, a separate supply of the rows with fresh lubricating oil can be provided. It is also preferably provided that the pressure values for the oil supply points 22 of a row R _i, which are at least partially independent of the pressure chamber, and / or the pressure values for the oil supply points of different rows, which are at least partially independent of the pressure chamber, can be set separately. It is also conceivable to set the pressure values of several oil supply points 22 together, as was described with reference to FIG. 3.

This setting can be done manually or electronically be controlled. It is also preferably ensured that that the oil pressure in the area of the inlet openings of the bores 26 at least temporarily set to such a high value can be that the roll shell 14 hydrostatic is supported. In practice, it is sufficient if such high pressure values are generated during start-up. While the operation should preferably be at least essentially one hydrodynamic lubrication.

The depressions 24 are continuous at least on one side into the support surface partially also formed by the webs 28 20 about. This transition is preferably made by a convex curvature. Such transitions can both in the direction of travel LW of the roll shell 14 (see. Figures 1, 4 and 7 to 9) and in the transverse direction of the support element 18 be (see FIG. 3). So it is especially so possible that the depressions continuously on all sides for example via a convex curvature in the partial pass through the support surface 20 formed by the webs 28. The depressions 24 advantageously each have one maximum depth T of less than 0.5 mm, in particular less than 0.3 mm and preferably less than 0.1 mm.

According to Figure 2, these recesses 24 are substantially round in plan view. In plan view, however, they can also have a rectangular, triangular or diamond shape or a contour with both rectilinear and curved or rounded boundaries. Here, the recesses 24 of a respective row R _i in plan view in particular also have such an identical or different contour that adjacent recesses 24 overlap while maintaining an intermediate web 28, viewed in the running direction LW.

In the embodiment shown in Figures 2 and 6 are the holes 26 of the oil supply points 22 in plan view viewed in the direction of travel LW of the roll shell 14 before Center of gravity arranged. Because of this arrangement there is an optimal oil distribution during operation in the recesses 24. However, it is also possible to use the Bores 26 in plan view in the respective area focus arrange the wells (Fig. 8).

In the exemplary embodiment shown in FIG. 5, several, here two, mutually parallel rows R _i each consisting of a plurality of separate oil supply points 22, which are at least partially independent of the pressure chamber, are provided. Here, the oil supply points 22 of the two adjacent rows R ₁ and R ₂ are transversely offset from each other to the running direction LW of the roll shell 14 by an amount A / 2. This amount A / 2 corresponds to half the distance 'A of the bores of a respective row of oil supply points, which distances are preferably essentially the same size in the two rows. The two rows R ₁ and R ₂ are therefore provided so that the respective oil supply points 22 are arranged on a gap.

In a preferred embodiment variant, the bores 26 of the oil supply points 22 of a row R _{i are arranged} at a distance A of approximately 5 to 50 mm, in particular 10 to 30 mm and preferably approximately 20 mm from one another. In addition, a distance of approximately 5 to 50 mm, in particular 10 to 30 mm and preferably approximately 20 mm, is provided between the bores 26 of the oil supply points 22 of two adjacent rows R _i in the running direction LW of the roller shell 14.

In particular with a view to optimally distributing the temperature over the support surface 20, it is particularly advantageous if at least one row R _i from a plurality of separate oil supply points 22, which are fed at least partially independently of the pressure chamber 19, viewed in the running direction LW of the roller jacket 14 in the region between 1/4 to 3/4, preferably 1/2 to 3/4 of the support surface 20 is arranged.

As can be seen in particular from FIG. 2, the Width B of the webs 28 is advantageously less than that Diameter D of the holes 26. In practice, the Width B of the webs 28, for example narrower than 10 mm, in particular narrower than 5 mm, preferably narrower than 1 mm and preferably be narrower than 0.2 mm.

The depressions 24 and the intermediate webs 28 are preferably through Etching and in particular produced by electroerosion.

The design variants of FIGS. 6 and 7 have in common that that the recess 24 of the respective oil supply point 22 in Running direction LW of the roll shell 14 over a longer one Route continuously into the support surface 20 of the Support element 18 passes into at the point in question 7 can be formed by a web 28 through which this oil supply point 22 is separated from the subsequent one.

FIG. 8 shows a number of oil supply points with a view in FIG Running direction LW. The depressions 24 of each bore 26 are separated by a web 28 at the level of the support surface 20. How results from this figure 8, the web width B is smaller than the diameter of the holes 26.

The oil supply can through at least one end face Support element, from the carrier or via a special oil feed pipe 44 (see Figure 1). Preferably every oil supply is pressure controlled. The oil flow through the Drilling is due to the pressure drop occurring at this regulated. In the manner described, the pressure oil can also be partially supplied via the pressure piston 38 (see Figure 4).

The pressure loss of the capillary-like bores results from the bore diameter, the bore length and the condition and the quantity of oil. Because of through achieved the webs and the capillary-like formation of the holes mutual separation of the oil supply points of the respective Row is different even when inconsistent Pressing ensures that all areas are adequate be supplied and the maximum outflow of oil through the drilling is limited. It is therefore also critical Operating conditions such as when running through optimal supply of oil from chunks or thickened paper to create and maintain the lubricating film 34 (see Figure 1) guaranteed. In addition, there is always a effective exchange of the oil adhering to the roller jacket ensured. There is an optimal temperature distribution with less heating of the lubricating film, which also means that the roller jacket is less thermal is charged. Also due to the lower warming of the lubricating film also the risk of thermal deformation of the support element is reduced. Even if there are any Irregularities can spread across the width of the Supporting element achieved uniform lubrication ratios become. Compared to a purely hydrodynamic or a purely hydrostatic lubrication also results greater freedom of design with regard to the pressure profile. The removal of angular depressions is also favorable in the area of the press zone.

Reference list

4th

Rolled product

6

Felt ribbon

8th

Counter roll

10th

Press roll

12th

carrier

14

Roller shell

16

Inner circumferential surface

18th

Support element

19th

Pressure room

20th

Support surface

22

Oil supply points

24th

deepening

26

drilling

28

Walkways

30th

Distribution channel

33

Supply

34

Lubricating film

36

Adjusting means

38

Pressure piston

B

Web width

D

Diameter of the depression

LW

Running direction

R

line

A

distance

T

Depth of depression

Claims (35)

1. Press roll with a stationary support (12) and a revolving roll cover (14), which is supported on the support (12) by at least one supporting element (18) that can be pressed against the inner circumferential face (16) of the roll cover (14), is at least partially hydrodynamically lubricated and has a supporting face (20) which faces the inner circumferential face (16) of the roll cover (14) and is lengthened in the running direction (LW) of the roll cover (14) and has at least one row (R_i), extending in the direction of the roll axis, of a large number of oil supply points (22) which are used for hydrodynamic lubrication during operation and via which the region between the supporting face (20) and inner circumferential face (16) of the roll cover (14) is supplied with fresh lubricating oil, and which are fed at least partly independently of a pressure chamber (19) that acts on the supporting belt (18),
   characterized in that the oil supply points (22) used for hydrodynamic lubrication are each formed by a local depression (24) in the supporting face (20), into which depressions a restricting bore (26) opens in each case, in that these oil supply points (22) are separated from one another by webs (28) which are provided between the depressions (24) and whose surfaces lie at least essentially at the same level as the remaining supporting face,
   in that the depressions merge continuously on all sides, preferably in each case via a convex curve, into the supporting face (20) formed partly by the webs (28),
   and in that the depressions (24) each have a maximum depth (T) of less than 0.3 mm and preferably less than 0.1 mm.
2. Press roll according to Claim 1, characterized in that the oil supply points (22) are each formed by a local depression (24) in the supporting face (20) and a restricting hole (26) opening into this depression (24), there being provided between the depressions (24) webs (28) whose surfaces lie at least essentially at the same level as the remaining supporting face.
3. Press roll according to Claim 1 or 2, characterized in that the row (R_i) of oil supply points (22) is assigned at least one distributor channel (30) which is provided in the supporting element (18) and via which a number of oil supply points (22) are supplied jointly with fresh lubricating oil.
4. Press roll according to Claim 3, characterized in that the distributor channel (30) extends generally in the direction of the roll axis.
5. Press roll according to one of the preceding claims, characterized in that a number of distributor channels (30) located one behind another in the direction of the roll axis are provided.
6. Press roll according to one of the preceding claims, characterized in that the distributor channel (30) has one or more entry openings, and in that the cross section of the entry openings or the sum of the cross sections of the entry openings is greater than the sum of the cross sections of the bores (26).
7. Press roll according to one of the preceding claims, characterized in that the bores (26) are designed like capillaries and each have a diameter in the range from about 0.3 mm to 3 mm, preferably 1 mm.
8. Press roll according to one of the preceding claims, characterized in that the bores (26) each have a length in the range from about 3 to 100 mm, preferably 5 to 50 mm.
9. Press roll according to one of Claims 1 to 6, characterized in that the bores (26) are assigned control apertures or the like.
10. Press roll according to one of the preceding claims, characterized in that the oil pressure in the region of the entry openings of the bores (26) is higher than the pressure in the lubricating film (34) over the supporting face (20) of the supporting element (18).
11. Press roll according to one of the preceding claims, characterized in that the bores (26) are, at least to some extent, connected individually to the distributor channel (30).
12. Press roll according to one of Claims 1 to 10, characterized in that the bores (26) are combined, at least to some extent, into groups and are connected to the distributor channel (30) in groups.
13. Press roll according to one of the preceding claims, characterized in that means (36) are provided in order to set the values for the pressure and/or quantity of the fresh lubricating oil supplied separately with respect to individual and/or groups of bores (26).
14. Press roll according to one of the preceding claims, characterized in that the supply of fresh lubricating oil to the oil supply points (22) of a row is carried out completely independently of the pressure chamber (19) that acts on the supporting element (18).
15. Press roll according to one of Claims 1 to 13, characterized in that the supply of fresh lubricating oil to the oil supply points (22) of a row is carried out partly via the pressure chamber (19) that acts on the supporting element (18).
16. Press roll according to one of the preceding claims, characterized in that the supply of fresh lubricating oil along the row (R_i) of oil supply points (22) is carried out alternately, independently of the pressure chamber (19) that acts on the supporting element (18) and via the pressure chamber that acts on the supporting element (18).
17. Press roll according to one of the preceding claims, characterized in that, in addition to the at least one row (R_i) of a large number of oil supply points (22) that are separated from one another and fed at least partly independently of the pressure chamber, there is provided at least one row, parallel thereto, of a large number of oil supply points which are separated from one another and fed via the pressure chamber.
18. Press roll according to Claim 17, characterized in that, in the running direction (LW) of the roll cover (14), there are provided alternately in each case a row (R_i) of a large number of oil supply points (22) which are separated from one another and fed at least partly independently of the pressure chamber, and a row, parallel thereto, of a large number of oil supply points (22) which are independent of one another and fed via the pressure chamber (19).
19. Press roll according to one of the preceding claims, characterized in that different rows in each case comprising a large number of oil supply points (22) which are separated from one another and fed at least partly independently of the pressure chamber are supplied with fresh lubricating oil separately from one another.
20. Press roll according to one of the preceding claims, characterized in that the pressure values for the oil supply points (22) of a row (R_i) which are fed at least partly independently of the pressure chamber, and/or the pressure values for the oil supply points (22) of different rows (R_i) which are fed at least partly independently of the pressure chamber can be set separately.
21. Press roll according to one of the preceding claims, characterized in that the oil pressure in the region of the entry openings of the bores (26) can be set, at least from time to time and preferably during start-up, to such a high value that the roll cover (14) is supported hydrostatically.
22. Press roll according to one of the preceding claims, characterized in that the depressions (24) merge continuously on at least one side, preferably in the running direction (LW), preferably via a convex curve, into the supporting face (20) formed partly by the webs (28).
23. Press roll according to one of the preceding claims, characterized in that the depressions merge continuously on all sides, preferably in each case via a convex curve, into the supporting face (20) formed partly by the webs (28).
24. Press roll according to one of the preceding claims, characterized in that the depressions (24) each have a maximum depth (T) of less than 0.5 mm, in particular less than 0.3 mm and preferably less than 0.1 mm.
25. Press roll according to one of the preceding claims, characterized in that, in plan view, the depressions (24) each have an essentially circular, triangular, square or lozenge shape.
26. Press roll according to one of the preceding claims, characterized in that, in plan view, the depressions (24) of the row (R_i) have an identical or different contour such that adjacent depressions (24) overlap, while maintaining a web (28) located between them.
27. Press roll according to one of the preceding claims, characterized in that, in plan view, the bore (26) of a respective oil supply point (22) is arranged at the area centre of gravity of the associated depression (24) or, as viewed in the running direction (LW) of the roll cover (14), upstream of this area centre of gravity.
28. Press roll according to one of the preceding claims, characterized in that a number of mutually parallel rows (R_i) each comprising a large number of oil supply points (22) which are separated from one another and at least partly fed independently of the pressure chamber are provided, and in that the oil supply points (22) of two adjacent rows (R_i) are preferably offset transversely with respect to the running direction (LW) of the roll cover (14), that is to say are arranged opposite gaps.
29. Press roll according to one of the preceding claims, characterized in that the bores (26) of the oil supply points (22) of a row (R_i) are arranged at a distance (A) from one another of about 5 to 50 mm, in particular 10 to 30 mm and preferably about 20 mm.
30. Press roll according to one of the preceding claims, characterized in that at least one row (R_i) comprising a large number of oil supply points (22) which are separated from one another and fed at least partly independently of the pressure chamber, as viewed in the running direction (LW) of the roll cover (14), is arranged in the area between ¼ to ¾ preferably ½ to ¾ of the supporting face (20).
31. Press roll according to one of the preceding claims, characterized in that the width (B) of the webs (28) is less than the minimum diameter (D) of the bores (26).
32. Press roll according to one of the preceding claims, characterized in that the width (B) of the webs (28) is narrower than 10 mm, in particular narrower than 5 mm, preferably narrower than 1 mm and preferentially narrower than 0.2 mm.
33. Press roll according to one of the preceding claims, characterized in that the depressions (24) provided in the supporting face (20) and the webs (28) located between them are formed by etching and in particular by electric spark erosion.
34. Press roll according to one of the preceding claims, characterized in that at least one row (R_i) has bores (26) only in the edge region, that is to say it has no bores in the central region.
35. Press roll according to one of Claims 1 to 33, characterized in that at least one row (R_i) has bores (26) only in the inner region.

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