CN113832764B

CN113832764B - Hot roll for a fiber web machine

Info

Publication number: CN113832764B
Application number: CN202110696214.7A
Authority: CN
Inventors: J·詹霍宁
Original assignee: Valmet Technologies Oy
Current assignee: Valmet Technologies Oy
Priority date: 2020-06-24
Filing date: 2021-06-23
Publication date: 2023-07-07
Anticipated expiration: 2041-06-23
Also published as: EP3929353B1; CN113832764A; EP3929353A1

Abstract

The present invention relates to a heat roller. The thermo roll (12) comprises a hollow roll body (13) with a plurality of grooves (14) on an outer surface (15) of the roll body. Each groove (14) extends from one end of the roller body (13) to the other end. An axial bore (16) is provided in the roller body (13) which opens into the recess (14). The thermo roll (12) further comprises a journal (17) having a conductor (18) extending to the axial bore (16) and being fixed to both ends of the roll body (13) by means of a plurality of bolts (19). The heat roller (12) further comprises an outer jacket (21) which is frictionally fitted over the roller body (13) and the journal (17) and closes the grooves (14) as a plurality of channels (22) for the heat transfer medium. Each axial bore (16) has an offset (23) leading to two adjacent grooves (14).

Description

Hot roll for a fiber web machine

Technical Field

The invention relates to a thermo roll for a fiber web machine, comprising:

-a hollow roll body having a plurality of grooves on an outer surface thereof, each groove extending from one end of the roll body to the other end and having an axial bore in the roll body leading to the groove;

-a journal having a conductor (conductor) extending to the axial bore and secured to both ends of the roller body by a plurality of bolts; and

an outer jacket which fits friction-fittingly over the roller body and the journal and which encloses the grooves as a plurality of channels for the heat transfer medium.

Background

Finnish patent No. 122707 discloses a thermo roll of a fiber web machine. The thermo roll has a roll body with two journals. The journal is bolted to the roll body. In addition, the roller body has a groove and an outer jacket. Thereby forming channels for the heat transfer medium. The journal and the roller body have bores (bore) for leading the heat transfer medium into and out of the channels. In practice, each groove has an axial bore.

Because of the space required for axial drilling and bolting, the known roll body diameters are large, as well as the wall thickness of the roll body itself. But also the journal weakens due to the drilling. The journal must also be large. These characteristics make the entire thermo roll large and heavy. This reduces the possibility of using the thermo roll in different positions.

Disclosure of Invention

The object of the present invention is to provide a thermo roll for a fiber web machine that is simpler than before, in particular of smaller diameter. The characteristics of the thermo roll according to the invention are given by the present disclosure. The thermo roll, particularly the roll body and the journal, has smaller bore holes than before. Thereby making it possible to small journals. At the same time, the wall thickness of the roller body can be smaller. Moreover, by arranging the bores in a new way, the wall thickness of the roll body can be minimized.

The invention relates to a thermo roll for a fiber web machine, comprising: a hollow roll body having a plurality of flutes on an outer surface thereof, each flute extending from one end of the roll body to the other end, and having an axial bore in the roll body leading to the flutes; journals having conductors extending to the axial bores and fixed to both ends of the roller body by a plurality of bolts; and an outer jacket friction fitted over the roller body and the journal, and the outer jacket closing the grooves as a plurality of channels for a heat transfer medium; wherein each axial bore has an offset leading to two adjacent grooves.

Preferably, each conductor comprises a radial bore between two adjacent grooves, the corresponding axial bore being arranged to open into the radial bore.

Preferably, there is one bolt between two radial bores.

Preferably, the axial bore and the bolt are substantially on the same radius relative to the centre of the journal.

Preferably there is a neck between the grooves, the axial bore being located at the neck.

Preferably, each bolt is located at the neck adjacent the axial bore.

Preferably, an insulating bushing is provided in the axial bore with an air gap (air gap) between the axial bore and the insulating bushing.

Preferably, the width of the neck is the same as the width of the groove.

Preferably, the depth of the grooves decreases in the flow direction of the heat transfer medium.

Preferably, the thickness of the outer sheath is 20-40mm.

Preferably, the hollow roller body has a wall thickness of 60-80mm.

Preferably, there is an additional insulating sleeve in the radial bore, with an air gap between the radial bore and the additional insulating sleeve.

Preferably, there is a central bore in the journal, inside which a flow divider is arranged at the start of the radial bore.

Preferably, both journals and their conductors are identical for transporting the heat transfer medium from one journal to the other via said channels.

Preferably, there is a central tube inside the central bore and the journal, which central tube is used for the input or return of the heat transfer medium.

Drawings

The invention will now be described in detail with reference to the accompanying drawings, which illustrate some embodiments of the invention, wherein:

FIG. 1 shows a schematic side view of a part of a fiber web machine equipped with a thermo roll according to the invention;

FIG. 2a shows a schematic cross-sectional view of a thermo roll according to the invention;

FIG. 2b shows a partial cross-sectional view of a thermo roll according to the invention;

FIG. 3 shows a schematic view of a thermo roll according to the invention, as seen from the thermo roll head;

fig. 4 shows a portion of a thermo roll without an outer sheath according to the invention.

Detailed Description

Fig. 1 shows a part of a fiber web machine in a side view. Here a calender 10 with a stack 11 of rolls. At least some of these rolls are thermo rolls 12. In a calender, the heated rolls are heated by a heat transfer medium, which is hot water or oil or other hot fluid. By heating, the properties of the fibrous web (e.g. paper) can be improved. Further, the guide roller may be a heat roller. Typically, the heated rolls are contacted with other rolls or heated rolls in a nip. The thermo roll according to the invention can also be used in other places where it is needed, for example in the dryer section of a fibre web machine.

Fig. 2a shows a cross section of a thermo roll 12 according to the invention. The thermo roll 12 is intended for a fibre web machine. The thermo roll 12 comprises a hollow roll body 13 having a plurality of grooves 14 on its outer surface 15. The recess 14 is shown in detail in fig. 4. The grooves may extend in the axial direction of the thermo roll, but may also extend, for example, at an angle or helically, to avoid, inter alia, blocking phenomena (barring phenomenon). Each groove 14 extends from one end of the roller body 13 to the other. In addition, there is an axial bore 16 in the roller body 13 leading to the recess 14. The thermo roll further comprises a journal 17 with a conductor 18 extending to the axial bore 16. Journals 17 are secured at both ends of the roll body 13 by a plurality of bolts 19. In fig. 2a two bolts 19 are shown and in fig. 3 holes 20 for the bolts are shown. The thermo roll 12 also includes an outer jacket 21 that frictionally fits over the roll body 13 and the journal 17. The friction fit is also known as an interference fit (interference fitting) or a press fit (press fit). The outer jacket 21 encloses the grooves 14 as a plurality of channels 22 for a heat transfer medium. In the embodiment shown in fig. 2a, the flow of heat transfer medium is shown with solid arrows. In the basic embodiment, the heat transfer medium is fed via the journal 17 to the axial bore 16 and from there into the recess 14 and finally out of the thermo roll via the further journal 17. The cross section of fig. 2a has two planes, which show the recess 14 (upper side) and the bolt 19 (lower side) with the axial bore 16, respectively.

In the present invention, each axial bore 16 has an offset (offset) 23 leading to two adjacent grooves 14. In other words one axial bore terminates in two adjacent grooves. This reduces the number of required drill holes by half. And simultaneously, the wall thickness of the roller body can be reduced. In practice the borehole is so large that it at least partly enters (reach) into both grooves 14 (fig. 4). Here, the axial bore 16 is mainly in the neck 24 between the two grooves 14. Therefore, axial drilling into two adjacent grooves can be simply machined by only one drilling (drilling). Alternatively, a small axial bore may be made first, followed by two oblique bores, each of which enters a recess.

Furthermore, the bolts are positioned in a new way. Advantageously, there is one bolt 19 between two radial bores 29. In other words, every second neck there is a bolt. More advantageously, the axial bore 16 and the bolt 19 are substantially on the same radius with respect to the centre of the journal 17 (fig. 3). In this way the thickness of the roller body can be minimized. Even so, there is still enough room for axial drilling and bolting. Only the holes 20 for the bolts are shown in fig. 3, not the bolts themselves. Here, there are necks 24 between the grooves 14, and the axial bores 16 and the bolts 19 are located in the necks 24. Moreover, each bolt 19 is located adjacent to the axial bore 16 at the neck 24. Thus, it is possible to use a bolt long enough to obtain a rigid fixation. More generally, the distance between the bolt and the axial bore is substantially the same as the radius (radius) drawn through the center of the bore for the bolt and intersecting the perimeter of the adjacent bore.

As previously mentioned, the journal 17 has a conductor 18 extending to the axial bore 16. First, there is a central bore 25 through the journal 17. At the inner end of the central bore 25 there is an enlargement 26 which forms a chamber 27 when the central bore 25 is closed by a wall 28. Furthermore, each conductor 18 comprises a radial borehole 29 between two adjacent grooves 14, the corresponding axial borehole 16 being arranged to open into the radial borehole 29. In other words, there is one radial borehole per axial borehole. When the number of axial bores is halved, the number of radial bores is halved. Thus, there is sufficient material between the radial bores so that the journal can withstand heavy loads.

After the outer sheath is installed, the radial bore is closed by the outer sheath. However, each radial bore 29 has a plug 30 to ensure tightness. The plug also serves as an insulation. For the same purpose, an insulating bush (insulation bushing) 31 is provided in the axial bore 16, with an air gap 32 between the axial bore 16 and the insulating bush 31. The insulating bush 31 ends just before the groove (fig. 2 b). This allows as much heat as possible to end up in the groove. The insulating bushings are replaceable and may have different bushing sets with different diameters. Thereby, the flow rate of the heat transfer medium can be adjusted as needed.

By arranging the drill holes in a new way, more grooves than before are possible. Advantageously, the width of the neck 24 is the same as the width of the groove 14. Thereby allowing heat to be transferred uniformly and sufficient space to attach the bolt. In addition, the temperature of the outer sheath is kept uniform, thereby improving the properties of the fiber web.

When the fluid flows in only one direction in the grooves, the depth of the grooves is reduced in the direction of flow of the heat transfer medium. This equalizes the residence time of the fluid. Therefore, even if the heat transfer medium is supplied from only one end of the heat roller, the temperature of the heat roller may be uniform. If the flow rate of the heat transfer medium is sufficiently large, the temperature of the heat roller is maintained uniform.

When positioning the axial bores and bolts according to the invention, the thermo roll can be optimized and minimized. In practice, the thickness of the outer sheath 21 is 20-40mm. In this way, heat is transferred more efficiently to the fiber web. At the same time, the mass of the thermo roll becomes smaller than before. Finally, it is still possible to grind the outer sheath by about 10mm.

The greatest weight reduction is achieved by reducing the wall thickness of the hollow roller body. According to this surprising idea, even a 6 meter long thermo roll, the hollow roll body may have a wall thickness of only 60-80mm. Therefore, the actual nip pressure is highly required, not the space required for drilling and bolting. Thereby, the size of the heat roller can be minimized and optimized.

In small heat rolls, for example 600mm in diameter, the width of the grooves may be about 20-30mm. When the dimensions of the necks are approximately the same, the temperature of the outer jacket is uniform over the entire diameter of the thermo roll.

As with the axial bore, there is also an additional insulating bushing 33 in the radial bore 29, with an air gap 34 between the radial bore 29 and the additional insulating bushing 33. This allows as much heat as possible to end up in the groove. The air gap may be filled with fluid, but when the fluid in the air gap remains stationary, it acts like air to insulate. Thus no sealant is required.

As previously mentioned, there is a central bore 25 in the journal 17. Advantageously, the starting point of the radial bore 29 is a flow divider 35 arranged inside the central bore 25. The flow splitter evenly splits the flow of heat transfer medium into radial bores. Thus, even if the heat roller rotates at a high speed, heat is uniformly distributed.

As shown in fig. 2a, both journals 17 and their conductors 18 are identical for conveying the heat transfer medium from one journal 17 to the other journal 17 via a channel 22. Thus, the heat transfer medium is fed in from one end of the heat roller and then led out from the other end of the heat roller. Alternatively, there may be a center tube 36 inside the center bore 25 and journal 17 for the input or return of the heat transfer medium, as shown herein. Whereby the heat transfer medium is fed in and out from one end of the thermo roll. This is shown by the dashed line in fig. 2 a. There is also a stop 37 which closes the central bore 25 and delivers the heat transfer medium to the central tube 36.

Claims

1. A thermo roll for a fiber web machine, the thermo roll (12) comprising:

-a hollow roller body (13) having a plurality of grooves (14) on its outer surface (15), each groove (14) extending from one end of the roller body (13) to the other end and having an axial bore (16) in the roller body (13) leading to the groove (14);

-a journal (17) having a conductor (18) extending to the axial bore (16), wherein a plurality of axial holes (20) for bolts (19) are provided at both ends of the roller body (13), and the journal is fixed to both ends of the roller body (13) by a plurality of bolts (19); and

an outer jacket (21) friction fitted over the roller body (13) and the journal (17), and the outer jacket (21) closing the grooves (14) as a plurality of channels (22) for a heat transfer medium,

characterized in that each axial bore (16) has an offset (23) leading to two adjacent grooves (14).

2. A thermo roll as claimed in claim 1, characterized in that each conductor (18) comprises a radial borehole (29) between two adjacent grooves (14), the corresponding axial borehole (16) being arranged to open into the radial borehole (29).

3. A thermo roll as claimed in claim 2, characterized in that there is a bolt (19) between two radial bores (29).

4. A thermo roll as claimed in any one of claims 1 to 3, characterized in that the axial bore (16) and the bolt (19) are substantially on the same radius with respect to the centre of the journal (17).

5. A thermo roll as claimed in claim 1, characterized in that between the grooves (14) there are necks (24) where the axial bores (16) are located.

6. A thermo roll as claimed in claim 5, characterized in that each bolt (19) is located at the neck (24) adjacent to the axial bore (16).

7. A thermo roll as claimed in claim 5 or 6, characterized in that an insulating bushing (31) is provided in the axial bore (16), with an air gap (32) between the axial bore (16) and the insulating bushing (31).

8. A thermo roll as claimed in claim 5 or 6, characterized in that the width of the neck (24) is the same as the width of the groove (14).

9. A thermo roll as claimed in claim 7, characterized in that the width of the neck (24) is the same as the width of the groove (14).

10. A thermo roll as claimed in any one of claims 1 to 3, characterized in that the depth of the grooves (14) decreases in the flow direction of the heat transfer medium.

11. A thermo roll as claimed in any one of claims 1 to 3, characterized in that the thickness of the outer jacket (21) is 20-40mm.

12. A thermo roll as claimed in any one of claims 1 to 3, characterized in that the hollow roll body (13) has a wall thickness of 60-80mm.

13. A thermo roll as claimed in claim 2 or 3, characterized in that an additional insulating bushing (33) is provided in the radial borehole (29), an air gap (34) being provided between the radial borehole (29) and the additional insulating bushing (33).

14. A thermo roll as claimed in claim 2 or 3, characterized in that there is a central bore (25) in the journal (17), at the start of the radial bore (29), inside the central bore (25) there is arranged a flow divider (35).

15. A thermo roll as claimed in claim 14, characterized in that both journals (17) and their conductors (18) are identical for conveying the heat transfer medium from one journal (17) to the other journal (17) via the channels (22).

16. A thermo roll as claimed in claim 14, characterized in that there is a central tube (36) inside the central bore (25) and the journals (17), which central tube is used for the input or return of the heat transfer medium.

17. A thermo roll as claimed in claim 15, characterized in that there is a central tube (36) inside the central bore (25) and the journals (17), which central tube is used for the input or return of the heat transfer medium.