US20210254283A1

US20210254283A1 - Roller for a machine for producing and/or processing a paper, cardboard, or tissue web, and method for operating the roller

Info

Publication number: US20210254283A1
Application number: US17/251,373
Authority: US
Inventors: Marc Erkelenz
Original assignee: Voith Patent GmbH
Current assignee: Voith Patent GmbH
Priority date: 2018-06-11
Filing date: 2019-06-05
Publication date: 2021-08-19
Also published as: DE102018113831A1; CN112313377A; EP3802951A1; WO2019238484A1; EP3802951B1; CN112313377B; EP3802951C0

Abstract

A roll for a machine for producing or processing a fibrous web includes a movable roll shell, a positive or negative pressure zone which is disposed within the roll shell and is rotationally fixed relative to the roll shell, and a sealing device for sealing the positive or negative pressure zone from the surroundings. The sealing device has a sealing strip and a lubricating device with which a lubricant can be introduced between the inner surface of the roll shell and the sealing surface of the sealing strip. The lubricating device includes a plurality of lubricant outlet openings and is connected to a supply line for supplying lubricant through a plurality of inlet segments. The supply line includes an inner section which runs within the roll shell, the inner section having a storage volume of at least 490 cm3/m. A method for operating a roll is also provided.

Description

The invention relates to a roll for a machine for producing and/or processing a fibrous web according to the preamble of claim 1, and a method for operating the roll according to the preamble of claim 13.
Sealing devices in evacuated or blown rolls of paper, board or tissue machines must reliably seal off the positive or negative pressure zone against the surroundings in which normal pressure prevails. Here, to seal the positive pressure or negative pressure zone, the sealing surface of each sealing strip of the sealing device is set against the inside of the rotating roll shell. In order to reduce the wear of the sealing strip caused by friction between the lateral surface and the sealing surface, attempts are made to introduce lubricant between the sealing surface and the inside. This is usually done with spray pipes which, in the direction of rotation of the roll, are arranged upstream of the first sealing strip of the positive or negative pressure zone. Here, the lubricant applied to the inside of the roll shell is conveyed by the rotation of the latter to the individual sealing strips, as a result of which, as seen in the direction of rotation, the lubricant supply decreases from sealing strip to sealing strip. In order nevertheless to supply the sealing strips following in the direction of rotation with sufficient lubricant, a large quantity of lubricant has to be used, which, however, benefits only a small part of the actual lubrication of the sealing strips and otherwise contributes only to the undesired re-wetting of the fibrous web.
To solve this problem, EP 2 885 457 and EP 3 022 356 propose to conduct the lubricant directly to the upper side of the respective sealing strip providing the sealing surface, in order thereby to supply each individual sealing strip specifically with the necessary quantity of lubricant. A preferred refinement of this invention here also proposes a lubricant channel, provided on the upper side of the roll in the form of a groove-like depression arranged on the sealing surface and extending in the longitudinal direction of the sealing strip, i.e. in the cross-machine direction of the roll, if necessary with the aid of a suitable lip.
Irrespective of which type of lubricating device is used, it is essential for low-wear operation of such a roll that the sealing surface of the sealing strip is adequately supplied with lubricant over its entire length, which is frequently 10 m or more. However, as small a quantity of lubricant as possible should be used for this lubrication, for economic reasons.
For this purpose, it would be desirable to be able to ensure the most uniform distribution of the lubricant as possible over the entire length of the sealing strip.
It is therefore an object of the invention to propose a roll having a sealing device in which a uniform supply of the sealing strip with lubricant is ensured. Furthermore, it is an object of the invention to indicate a reliable method for operating such a roll while using a small quantity of lubricant.
With regard to the roll, the object is completely achieved by a roll for a machine for producing or processing a fibrous web according to the characterizing part of claim 1 and, with regard to the method, by a method for operating a roll for a machine for producing or processing a fibrous web according to the characterizing part of claim 13.
Further advantageous embodiments are described in the sub-claims.
A roll is proposed for a machine for producing or processing a fibrous web, which comprises a movable roll shell and a positive or negative pressure zone which is arranged within the roll shell and is fixed against rotation relative to the roll shell, and a sealing device for sealing off the positive or negative pressure zone with respect to the surroundings. The sealing device here has a sealing strip and a lubricating device, by means of which a lubricant can be introduced between the inside of the roll shell and the sealing surface of the sealing strip, wherein the lubricating device comprises a plurality of lubricant outlet openings and is connected via multiple inlet segments to a supply line for the supply with lubricant. According to the invention, the roll is characterized in that the supply line comprises an inner section which extends within the roll shell, and this inner section has a storage volume of at least 490 cm³/m, in particular at least 500 cm³/m, in particular of at least 750 cm³/m or 1000 cm³/m, based on the length of the sealing strip.
An inlet segment is intended to be understood to be a line part which is connected to the supply line which supplies the entire lubricating device and conducts lubricant to some of the lubricant outlet openings.
Trials by the applicant have surprisingly shown that, with such a supply line of the sealing device, a uniform lubricant distribution can be implemented. As a result of the buffering action of the comparatively large storage volume of the supply line, it is possible to ensure that all the inlet segments are supplied with the same pressure, or that the pressure difference is at least so small that it has no noticeable influence on the distribution of the lubricant. This represents a significant difference from the rolls known from the prior art. There, a normally thin supply line is led into the roll from one side, and the inlet segments to the lubricating device branch off from this supply line. This leads to a noticeably lower pressure being present in the inlet segments located further downstream in the flow direction of the lubricant and a smaller quantity of lubricant being supplied to the lubricating device. This effect is largely avoided by the storage volume in the present roll.
The size of the storage volume should be at least 490 cm³/m, in particular at least 500 cm³/m. The value of 490 cm³/m or 500 cm³/m is sufficient for the quantities of lubricant of 0.5 l/m/min to about 3 l/m/min that are normally used. Larger storage volumes of 1000 cm³/m, 2000 cm³/m or more are advantageous for reasons of evening out the pressure, as described above. Because of the quite restricted installation space in some rolls, or for economic reasons, it may be expedient to limit the size of the storage volume of fluid. Thus, it may be advantageous to provide the storage volume to be no greater than 20,000 cm³/m or than 10,000 cm³/m.
The statement of the storage volume in “cm³/m” relates respectively to the length of the lubricated sealing strip. Advantageously, the roll can be designed as a suction roll. In such suction rolls, the roll shell has openings which are usually arranged in the form of a regular pattern. Thus, by means of the negative pressure prevailing in the negative pressure zone, water can be extracted from a fibrous web or clothing through the openings in the roll shell.
In an advantageous embodiment of the invention, provision can be made for the inner section to comprise a pipe-shaped part or to consist thereof, which extends substantially over the entire length of the sealing strip, wherein this pipe has an internal diameter of 25 mm or more at at least one point, in particular more than 40 mm, preferably 50 mm or more. Such an embodiment is advantageous since, in this way, two properties of the supply line are simultaneously fulfilled, namely the distribution of the lubricant over the length of the roll and the sealing strip and the provision of the storage volume. In particular, provision can advantageously be made that the pipe has a constant cross section over more than 50% of its length, in particular over its entire length. A pipe which has an internal diameter of 25 mm over the entire length provides, for example, about 490 cm³/m, that is to say around 500 cm³/m of storage volume. In another advantageous embodiment, provision can be made for the pipe to taper continuously over its length. Such an embodiment can be advantageous in particular in the case of long sealing strips of more than 5 m or more than 10 m, in order to keep the pressure still further constant on inlet segments placed downstream in the flow direction of the lubricant.
In preferred embodiments, provision can further be made for the plurality of the lubricant outlet openings to be distributed uniformly over the length of the sealing strip and, in particular, for the spacings of adjacent lubricant outlet openings to differ by less than 25% or less than 10%. In addition to the uniform supply of the inlet segments, a distribution of the lubricant outlet openings of this type also assists the uniform distribution of the lubricant over the entire length of the sealing strip.
Advantageously, the spacing of two adjacent lubricant outlet openings can be between 20 mm and 200 mm, in particular between 30 mm and 100 mm. In particularly preferred embodiments, the spacing of adjacent lubricant outlet openings is between 40 mm and 60 mm.
The lubricating device can be implemented, for example, by lubricant being guided from the inlet segments to nozzle devices, for example fan nozzles, which represent the lubricant outlet openings. Via the nozzles, the lubricant is lubricated in the direction of the sealing surface to be lubricated. These nozzle devices are known as lubricating spray pipes and are usually arranged upstream of the sealing strip in the direction of rotation of the roll.
However, it may also be advantageous for the lubricating device to be provided wholly or partly in or on the sealing strip, wherein in particular the lubricant outlet openings are located in the sealing strip. Sealing strips of this type with an integrated lubricating device are therefore frequently preferred since the lubrication of the sealing surface can be implemented with a smaller quantity of lubricant.
Provision can also be made for the inner section to be designed to be at least partly rigid. Here, the term “rigid” is to be understood in comparison with the inlet segments. Frequently, inlet segments are designed wholly or at least partly as a plastic hose. This is expedient in particular in sealing strips with an integrated lubricating device, since the inlet segment must move together with the movement of the strip caused by the wear. For reasons of stability and simpler handling, it may be advantageous if the inner section of the supply line is at least partly made from a rigid material, e.g. in the form of a metallic pipe or a plastic pipe.
Frequently, sealing devices have a so-called holder for holding the sealing strip. In a preferred embodiment, provision can be made for the inner section to extend at least partly on or in this holder.
In preferred embodiments, provision can be made for all the inlet segments to have the same length or to differ by less than 25% in their length. In the event of excessively large differences in the lengths of the inlet segments, there may be the danger that the action of evening out the pressure, achieved by the invention, cannot be passed on completely as far as the lubricant outlet openings. Advantageously, the length of the inlet segments can be between 150 mm and 700 mm, in particular between 200 mm to 400 mm.
It is a very advantageous embodiment here if the inner section of the supply line is mounted on the outside of the suction box of a negative pressure zone. Firstly, this mounting position is more easily accessible than in the interior of the suction box. Secondly, the distance from the inner section of the supply line to the inlets of the sealing strip is usually smaller, so that it is possible to manage with shorter inlet segments having a length of, for example, 150 mm-250 mm.
The spacing of an inlet segment from an end of the sealing strip on the longitudinal side can preferably be at most 800 mm, in particular at most 600 mm, preferably 400 mm or less.
Alternatively or additionally, provision can be made for the inlet segments to be arranged such that their spacing from one another in the longitudinal direction of the roll is less than 2 m, in particular less than 1.75 m, preferably 1.5 m or less. In particular, the inlet segments can also be arranged such that the spacing of adjacent inlet segments from one another in the longitudinal direction of the roll is equal or differs only by less than 15%, in particular less than 5%.
Furthermore, it may be advantageous if the supply line additionally has an outer section, which extends substantially outside the roll, wherein the outer section, having an internal diameter of 25 mm or less, in particular 20 mm or less, or 15 mm or less, is guided via an end face into the interior of the roll, where it is connected to the inner section. In particular, the outer section can have a lower internal diameter than the inner section, in particular also at the connecting point of the two sections.
With regard to the method, the object is achieved by a method for operating a roll for a machine for producing or processing a fibrous web, wherein the roll is designed according to one of the previous claims, characterized in that the lubricating device is supplied with less than 2.4 l/min/m, in particular between 0.4 l/min/m and 1.5 l/min/m, of lubricant. Given such a quantity of lubricant, the roll according to one of the aforementioned aspects proves to be particularly advantageous.
Furthermore, it may be advantageous that, over a starting time period, the lubricating device is supplied with a first quantity of lubricant and, after this starting time period, the lubricating device is supplied with a second quantity of lubricant, wherein the first quantity of lubricant is greater, in particular more than 25% greater, than the second quantity of lubricant—in each case based on l/min/m.
Thus, for example, over a starting time period, the lubricating device is supplied with 2.4 l/min/m or more of lubricant and, after the starting time period, the quantity of lubricant is reduced to less than 2.4 l/min/m, in particular between 0.4 l/min/m and 1.5 l/min/m.
Such a starting time period can be, for example, at least 30 s, in particular between 30 s and 5 min. Such a starting time period, which precedes the standard operation, can ensure, amongst other things that the storage volume is completely filled with lubricant and thus the roll and the lubricating device can develop their full action.
The lubricant used can normally be a water, to which additives can be added if appropriate. The pressure in the supply line can be, for example, between 2 and 8 bar, in particular 4 to 6 bar.
A further idea which, even taken on its own, represents an inventive achievement but can also be used in combination with a roll according to one aspect of the invention relates to a sealing device for sealing off a positive or negative pressure zone of a roll for a machine for producing or processing a fibrous web, wherein the sealing device has a sealing strip and a lubricating device, by means of which, when used as intended, a lubricant can be introduced between the inside of the roll shell and the sealing surface of the sealing strip, and wherein the lubricating device comprises a plurality of lubricant outlet openings and can be connected to a supply line for supplying with lubricant. The sealing device is characterized in that the lubricating device can be connected to the supply line via a plurality of inlets which are distributed over the length of the sealing strip, the sealing strip has a first and a second longitudinal end, and the spacing from at least one, preferably both, longitudinal ends to an inlet is at most 800 mm, in particular at most 600 mm, preferably 400 mm or less.
As already mentioned, such a sealing device can be used in a roll according to an aspect of the invention, that is to say in particular in combination with a supply line which has a storage volume of at least 490 cm³/m, in particular at least 500 cm³/m. The inlet segments mentioned at the beginning can be connected to the inlets of the sealing device described here. However, such a sealing device is also advantageous when considered on its own.
Such a sealing device may in particular be advantageous also to supply the edges of the sealing strip adequately and uniformly with lubricant. Over the greatest part of the length of the sealing strip, each point can be supplied with lubricant both from the left and from the right, since there is at least one inlet on both sides, via which the lubricating device is supplied with lubricant. In the edge regions of the sealing strip on the other side of the first and last inlet, however, the problem arises that these regions are supplied with lubricant only from one side, since there is an inlet only on one side. This can lead to the region of the longitudinal ends of the sealing strip not being supplied with sufficient lubricant, specifically also with less lubricant than the central region of the sealing strip.
Advantageous embodiments of such a sealing strip are described below.
Thus, provision can advantageously be made for the inlets to be arranged such that their spacing from one another in the longitudinal direction of the roll is less than 2 m, in particular less than 1.75 m, preferably 1.5 m or less. In particular, the inlets can also be arranged such that the spacing of adjacent inlets from one another in the longitudinal direction of the roll is equal or differs only by less than 15%, in particular less than 5%.
Preferably, the lubricating device can be provided wholly or partly in or on the sealing strip, wherein in particular the lubricant outlet openings can be in the sealing strip.

The invention will be explained in more detail below by using schematic drawings, the invention not being restricted to these embodiments.

FIG. 1 shows a detail of a roll according to one aspect of the invention

FIG. 2 shows a detail of the roll according to a further aspect of the invention

FIG. 3 shows a detail of a roll according to a further aspect of the invention

FIG. 4 shows a detail of a roll according to a further aspect of the invention.

FIG. 1 shows a roll 1 having a roll shell 11 and an end face 12. Such a roll can be, for example, a suction roll 1. A sealing device 2 is provided in the interior of the roll 1. The former comprises a sealing strip 3, which is arranged in a sealing strip holder 3 a, and a lubricating device 4. The lubricating device 4 shown in FIG. 1 is largely located in the sealing strip 3. A multiplicity of lubricant outlet openings 5 are arranged beside one another. These openings 5 are placed such that the emerging lubricant gets between the sealing surface of the sealing strip 3 and the roll shell 11. For the supply of the lubricating device 4 with lubricant, e.g. with lubricating water, a supply line 6 is provided, which comprises an inner section 7 which extends in the interior of the roll shell 11, and has a storage volume of at least 490 cm³/m, in particular at least 500 cm³/m, preferably of at least 2000 cm³/m, based on the length of the sealing strip, and an outer section 8. Via a plurality of inlet segments 9, 9 a, the lubricating device 4 is connected to the inner section 7 of the supply line 6 at a plurality of inlets 10, 10 a. In advantageous embodiments, the spacings of two adjacent inlet segments 9, 9 a and/or two adjacent inlets 10, 10 a can each be equal. Alternatively or additionally, provision can also be made for the inlet segments 9, 9 a to be arranged such that their spacing from one another in the longitudinal direction of the roll 1 is less than 2 m, in particular less than 1.75 m, preferably 1.5 m or less. The spacing of an inlet segment 9 a or an inlet 10 a from a longitudinal end of the sealing strip 3 can preferably be at most 800 mm, in particular at most 600 mm, preferably 400 mm or less. Advantageously, the length of the inlet segments can be between 150 mm and 700 mm, in particular between 200 mm and 400 mm. It is a very advantageous embodiment here when the inner section 7 is mounted on the outside of the suction box of a negative pressure zone. Firstly, this mounting position is more easily accessible than in the interior of the suction box. Secondly, the spacing of the inner section 7 of the supply line to the inlets 10, 10 a of the sealing strip is usually lower, so that it is possible to manage with shorter inlet segments 9, 9 a with a length of, for example, 150 mm-250 mm.
The inner section 7 of the supply line in FIG. 1 comprises a pipe-shaped part. This pipe advantageously be made of a material (e.g. metal or plastic) which is more rigid than the inlet segments 9, 9 a. It is possible, for example, to use pipes having internal diameters of 25 mm (corresponding to a storage volume of about 500 cm³/m), 40 mm or 50 mm (corresponding to a storage volume of about 2000 cm³/m). The inlet segments 9, 9 a can be embodied, for example, as hose segments.
FIG. 2 differs from FIG. 1 in that the inner section 7 consists of a pipe 7 which tapers continuously over its length.
FIG. 3 shows a sealing strip 3 in a holder 3 a, which is pressed against the inside of the roll shell 11 of the roll 1 by means of a pressure hose 13. Such a use of a pressure hose for pressing onto a moving surface such as a roll shell is a measure which is usual and known to those skilled in the art. As distinct from the embodiments shown in FIGS. 1 and 2, in FIG. 3 the lubricating device 4 is not integrated into the sealing strip. The lubrication is implemented by means of a number of spray nozzles, which provide the outlet openings 5. The spray nozzles are connected to the inner section 7 of the supply line via inlet segments 9.
A further advantageous feature which, in FIG. 3, is implemented together with the spray nozzles but which is also possible in combination with a lubricating device 4 integrated into the sealing strip 3, consists in the inner section 7 of the supply line extending at least partly at least partly on or in the sealing strip holder 3 a. This inner section 7 provides the storage volume of at least 490 cm³/m, in particular at least 500 cm³/m, and can, for example, have the form of a cylinder or a tapering cylinder.
In FIG. 4, essential components of the invention are illustrated, once more schematically. In a sealing strip 3 with an integrated sealing device, the lubricant outlet openings 5 are supplied with lubricant via inlets 10, 10 a. The inlets 10, 10 a are connected to the inner section 7 of the supply line via inlet segments 9, 9 a. The inner section 7 is again embodied as a pipe, which also provides the storage volume. The spacings of the longitudinal end of the sealing strip 3 from the first inlet 10 a and from the first inlet segment 9 a are designated by d1 and d5, while the spacings of adjacent inlets 10, 10 a and adjacent inlet segments 9, 9 a from one another are designated by d2, d3, d4. The number of four inlets here is exemplary. It is entirely possible for more or fewer inlets/inlet segments to be provided.
The following table indicates some advantageous spacings of the inlet segments and the inlets.


Example No.	d₁	d₂	d₃	d₄	d₅

#1	400 mm	1360 mm	1360 mm	1360 mm	400 mm
#
2	640 mm	1200 mm	1200 mm	1200 mm	640 mm
#
3	540 mm	1250 mm	1300 mm	1250 mm	540 mm

As can be seen in, the “inner” spacings d2−d4 can be equal or differ by a few millimeters. This can be necessitated, for example, by the installation situation.

LIST OF DESIGNATIONS

1 Roll
2 Sealing device
3 Sealing strip
3 a Holder
4 Lubricating device
5 Lubricant outlet openings
6 Supply line
7 Inner section
8 Outer section
9, 9 a Inlet segment
10, 10 a Inlet
11 Roll shell
12 End face
13 Pressure hose

Claims

1-16. (canceled)

17. A roll for a machine for producing or processing a fibrous web, the roll comprising:

a movable roll shell having an inner surface and a positive or negative pressure zone disposed within said roll shell and fixed against rotation relative to said roll shell;

a sealing device for sealing off said positive or negative pressure zone from the surroundings, said sealing device having a sealing strip with a length and a sealing surface and said sealing device having a lubricating device for introducing a lubricant between said inner surface of said roll shell and said sealing surface of said sealing strip, said lubricating device including a plurality of lubricant outlet openings;

a supply line for supplying lubricant, said supply line including an inner section extending within said roll shell, said inner section having a storage volume of at least 490 cm³/m based on said length of said sealing strip; and

a plurality of inlet segments connecting said lubricating device to said supply line.

18. The roll according to claim 17, wherein said storage volume is at least 2000 cm³/m.

19. The roll according to claim 17, wherein said inner section includes or is formed of a pipe-shaped part extending substantially entirely over said length of said sealing strip, said pipe-shaped part having an inside diameter of 25 mm or more at least at one location.

20. The roll according to claim 19, wherein said inside diameter of said pipe-shaped part is more than 40 mm.

21. The roll according to claim 19, wherein said inside diameter of said pipe-shaped part is 50 mm or more.

22. The roll according to claim 19, wherein said pipe-shaped part has a length and a constant cross section over more than 50% of its length or over its entire length.

23. The roll according to claim 19, wherein said pipe-shaped part has a length and tapers continuously over its length.

24. The roll according to claim 17, wherein said plurality of lubricant outlet openings are distributed uniformly over said length of said sealing strip or said plurality of lubricant outlet openings include adjacent lubricant outlet openings separated by spacings differing by less than 25% from each other.

25. The roll according to claim 17, wherein said lubricating device is provided wholly or partly in or on said sealing strip, or said lubricant outlet openings are formed in said sealing strip.

26. The roll according to claim 17, wherein said inner section is at least partly rigid.

27. The roll according to claim 17, wherein said sealing device includes a holder for holding said sealing strip, and said inner section extends at least partly on or in said holder.

28. The roll according to claim 17, wherein all of said inlet segments have a length being identical to each other or differing by less than 25% from each other.

29. The roll according to claim 17, wherein said inlet segments have a length of between 150 mm and 700 mm.

30. The roll according to claim 17, wherein said inlet segments have a length of between 200 mm and 400 mm.

31. The roll according to claim 17, wherein said supply line has an outer section extending substantially outside the roll, said outer section having an inside diameter of 25.4 mm or less, and said outer section having an end face guided into an interior of the roll and connected to said inner section.

32. The roll according to claim 31, wherein said inside diameter of said outer section is 12.7 mm or less.

33. The roll according to claim 17, wherein said inlet segments include adjacent inlet segments separated from each other in a longitudinal direction of the roll by spacings being equal to one another or differing from one another by less than 15%.

34. The roll according to claim 33, wherein said spacings differ from one another by less than 5%.

35. The roll according to claim 17, wherein said inlet segments are separated from each other in a longitudinal direction of the roll by spacings of less than 2 m.

36. The roll according to claim 35, wherein said spacings between said inlet segments are less than 1.75 m.

37. The roll according to claim 35, wherein said spacings between said inlet segments are 1.5 m or less.

38. A method for operating a roll for a machine for producing or processing a fibrous web, the method comprising:

providing a roll according to claim 17; and

supplying said lubricating device with less than 2.4 l/min/m of lubricant.

39. The method according to claim 38, which further comprises supplying said lubricating device with between 0.4 l/min/m and 1.5 l/min/m of lubricant.

40. The method according to claim 38, which further comprises:

supplying the lubricating device with a first quantity of lubricant over a starting time period; and

supplying the lubricating device with a second quantity of lubricant after the starting time period;

the first quantity of lubricant being greater than the second quantity of lubricant.

41. The method according to claim 40, wherein the first quantity of lubricant is more than 25% greater than the second quantity of lubricant.

42. The method according to claim 38, wherein the starting time period is at least 30 seconds.

43. The method according to claim 38, wherein the starting time period is between 30 seconds and 5 min.