EP1387993B1 - Through-flow cylinder - Google Patents

Abstract

The cylinder (12) comprises fiber-reinforced plastic. Preferred features: The plastic matrix resists temperatures up to 300 deg C, and is e.g. a resin. At least one fiber layer is included. Its coefficient of thermal expansion alpha , is less than that of steel at about 300 deg C. It is preferably between zero and 9 x 10power<-6> K<-1>. The alpha value for the fiber-reinforced plastic, is 3 x 10power<-6> K<-1> at most; preferably one third of this or lower. Preferably more than 30%-70% of the fibers are circumferentially-orientated. Cylinder diameter is 2.5-4.5 m or more. At least its casing is carbon fiber-reinforced plastic. It has circumferential and axial webs. The circumferential webs have correspondingly-orientated reinforcing fibers, the axial webs are metal, with recesses for the circumferential webs. They are adhered together. A moveable bearing is included. Further variations of the web reinforcements are described. The casing has square or rectangular openings between webs. The open area is 95% to 98%. Openings are 60 mm x 120 mm. Axial webs are higher than circumferential webs and stand out radially. A sieve-based variant is described. A winding process is employed to make the fiber-reinforced version. A further segmented variant is described. Axial webs are preferably greater than 100-200 mm in height. There are channels between openings. Casing thickness preferably exceeds 100-200 mm.

Description

The invention relates to a flow-through cylinder for a through-flow drying plant, in particular for tissue. A flow-through cylinder of this type is specified, for example, in an article "High-tech through-flow drying for tissue" by Fleissner GmbH in ipw 3/2001, page 21.

The previously known flow-through cylinders, also referred to as TAD (through-air drying) cylinders, are made of metal. The tissue web is guided over the flow-through cylinder on a sieve. In this case, a gaseous medium is pressed through the tissue web by means of the flow-through. This gaseous medium or fluid may have a temperature of over 300 ° C. In the case of a web break, this temperature acts directly on the sieve, which is no longer cooled by the tissue web. In order to avoid damage to the screen due to the high temperature, the screen is cooled using a cold water spray tube shock. This thermal shock is also exposed to the flow-through cylinder, which leads to extreme thermal stresses. In order to prevent cracking of the metal or to reduce the risk of tearing, elaborate constructions are necessary (see the article "Hightech Durchströmtrocknung für Tissue" by Fleissner GmbH in ipw 3/2001, page 21).

A flow according to. The preamble of claim 1 is known from US-A-5766120 known.

The aim of the invention is to provide an improved flow cylinder of the type mentioned, in which the aforementioned problems are eliminated.

This object is achieved by the features listed in the characterizing part of claim 1.

In this case, the material of the fiber-reinforced plastic, in particular glass fibers, aramid fibers and / or preferably obtained carbon fibers. The flow-through cylinder can thus consist at least partially in particular of carbon-reinforced plastic (CFRP).

Advantageously, the matrix material of the fiber-reinforced plastic from a preferably at least up to 300 ° C heat-resistant material. This material may be, for example, resin or the like.

It is advantageous if at least one fiber layer is provided and the fiber layer is selected so that the thermal expansion coefficient α of the fiber-reinforced plastic is smaller than that of steel at about 300 ° C., and preferably in a range 0 ≦ α <9 × 10 ^-6 × 1 / Kelvin lies.

insbesondere kleiner als etwa $2\cdot {10}^{-6}\cdot \frac{1}{K}$

und vorzugsweise kleiner als etwa $1\cdot {10}^{-6}\cdot \frac{1}{K}\mathrm{.}$

Preferably, the thermal expansion coefficient α of the fiber-reinforced plastic is smaller than approximately at least in the circumferential direction $3\cdot {10}^{-6}\cdot \frac{1}{K}.$

especially smaller than about $2\cdot {10}^{-6}\cdot \frac{1}{K}$

and preferably less than about $1\cdot {10}^{-6}\cdot \frac{1}{K}\mathrm{,}$

This can be achieved, for example, in that in the production of the fiber-reinforced, for example carbon fiber reinforced, plastic suitably more than about 30%, in particular more than about 50% and preferably more than about 70% of the fibers are oriented at least substantially in the circumferential direction.

Unfavorable is, however, that the flexural rigidity of the cylinder in question is very small. Such a fiber layer is therefore not possible, for example, in guide rolls or smaller cylinders. In these, the fibers are axially aligned at least in the outermost layer (cf., for example EP-A-0 363 887 ). According to a preferred embodiment of the flow-through cylinder according to the invention, the cylinder diameter is therefore ≥ 2, 5 m, in particular> 4 m and preferably> 4.5 m, whereby a sufficient flexural rigidity is ensured even with wide tissue machines greater than 5 m.

The flow-through cylinder may generally comprise a jacket, end caps with bearing journals and at least on one side, preferably the drive side, a fluid outlet, for example air outlet. If appropriate, it is also possible to provide a feed connection or a fluid supply opening. In the interior of the flow-through cylinder, a suction box or a blow box can accordingly be provided, through which the drying fluid, for example drying air, can be removed or supplied. The suction or blow box can span at least substantially the region or sector of the flow-through cylinder which is looped around by the web, as a result of which false air or leakage air is avoided. Alternatively, the non-looped area can be covered, for example, with a cover plate to avoid false air.

The jacket can be made of individual elements, for example.

After the fibers of the fiber-reinforced plastic of the circumferentially extending webs are oriented mainly in the circumferential direction, resulting in the circumferential direction, a small thermal expansion coefficient α.

The extending in the circumferential direction webs are preferably glued to the axially extending webs.

Since the metal webs extending in the axial direction can expand with a corresponding temperature change, the flow-through cylinder is expediently provided with a floating bearing to absorb the corresponding axial displacements.

An advantageous alternative embodiment of the flow-through cylinder according to the invention is characterized in that it extends in the circumferential direction, in particular annular webs and extending in the axial direction webs that both the circumferentially extending webs and extending in the axial direction webs each consist at least partially of fiber-reinforced plastic and in that the webs extending in the circumferential direction and the webs extending in the axial direction are connected to one another in a form-fitting manner and are preferably adhesively bonded together.

The fibers in the circumferentially extending webs are preferably oriented in the circumferential direction and the fibers in the axially extending webs in the axial direction, which brings a high flexural rigidity for the flow-through cylinder with it.

The jacket is expediently provided with quadrangular, in particular square or preferably rectangular openings. These passage openings can be formed in particular between the webs. The open area is preferably in a range of about 95% to 98%. Preferred dimensions of the openings are 60 mm x 120 mm.

In certain cases, it is advantageous if the axially extending webs are higher than the circumferentially extending webs. Thus, according to an expedient alternative embodiment of the According to the invention flow through the cylinder extending in the axial direction webs with respect to the circumferentially extending webs radially outwardly projecting. In this case, the Durchströmsieb rests on the axially extending webs.

The flow-through cylinder can for example also consist of segments which are glued together and / or screwed. It is also conceivable that it consists of individual short cylindrical sections, e.g. glued or screwed together. A consequent advantage is that a smaller autoclave is sufficient in the curing process.

It is also possible, for example, that both the webs running in the circumferential direction and the webs extending in the axial direction end in the circumferential plane of the flow-through cylinder. In this case, the through-flow screen, also referred to as TAD (through air drying) screen, rests on the circumferentially extending ridges and the axial ridges.

The flow-through cylinder may be covered with a screen sock in order to uniform the flow of the passing gaseous medium, for example air, and thereby avoid markings. This is particularly advantageous when the open area is less than 96%. The Siebstrumpf can for example consist of a preferably at least 250 ° C heat resistant material, for example metal.

The webs extending in the axial direction and the webs running in the circumferential direction may have openings which allow cross flows and thus equalize the flow.

In a further expedient embodiment, the jacket of the flow-through cylinder consists of layers of fiber-reinforced plastic produced in particular by the winding method. It can be provided, for example, with round, square and / or rectangular openings. The openings may already be recessed in the manufacturing process (e.g., winding process) or subsequently machined, i. in particular by drilling and / or milling generated.

Fig. 1

eine schematische Teildarstellung einer Durchströmungstrocknungsanlage insbesondere für Tissue mit einem erfindungsgemäßen Durchströmzylinder,

Fig. 2

eine perspektivische Darstellung des in der Fig. 1 gezeigten Durchströmzylinders,

Fig. 3

einen schematischen Ausschnitt aus dem Mantel einer aus mehreren Einzelelementen hergestellten Ausführungsform des Durchströmzylinders,

Fig. 4

einen schematischen Ausschnitt aus dem Mantel einer Ausführungsform des Durchströmzylinders, bei der der Mantel aus insbesondere nach dem Wickelverfahren erzeugten Lagen aus faserverstärktem Kunststoff besteht und mit beispielsweise runden Durchtrittsöffnungen versehen ist, und

Fig. 5

einen schematischen Schnitt durch den in der Fig. 4 gezeigten Zylindermantel.

The invention is explained in more detail below with reference to embodiments with reference to the drawing; in this show:

Fig. 1

FIG. 2 a schematic partial representation of a through-flow drying plant, in particular for tissue with a flow-through cylinder according to the invention, FIG.

Fig. 2

a perspective view of the flow-through cylinder shown in FIG. 1,

Fig. 3

a schematic section of the jacket of an embodiment of the flow-through cylinder produced from a plurality of individual elements,

Fig. 4

a schematic section of the jacket of an embodiment of the flow-through, in which the jacket consists of layers produced in particular by the winding process consists of fiber-reinforced plastic and with For example, round passages is provided, and

Fig. 5

a schematic section through the cylinder jacket shown in FIG. 4.

1 shows a schematic partial representation of a through-flow drying plant 10, in particular for tissue.

This through-flow drying plant 10 comprises a flow-through cylinder 12, around which a Durchströmsieb 14 is guided. Together with the Durchströmsieb 14 a tissue web is guided around the flow cylinder 12.

The flow-through cylinder 12 is associated with a hood 16, which is supplied in the present case via a line 18 dry hot air, which is supplied by a burner 20.

In the interior of the flow-through cylinder 12, a suction box or a blow box can be provided, through which the drying air can be removed or supplied. In the present case, a suction box 22 is provided in the interior of the flow-through cylinder 12. The mixture of hot air and steam is removed via lines 24. A portion of this mixture can also be fed back to the burner 20 via a line 26.

As can also be seen in particular with reference to FIG. 2, the throughflow cylinder 12 comprises a jacket 28, end-side cover 30, and, at least on one side, preferably the drive side, a vent opening 32 for damp hot air. In the present case, this vent opening is provided in the respective journal 34.

The axis of the flow-through cylinder 12 is indicated in Fig. 2 with "X". The purely schematically indicated surface 28 of the flow-through cylinder 12 is provided with passage openings 36.

At least the jacket 28 of the flow-through cylinder 12 is at least partially made of fiber-reinforced plastic. The material of the fiber-reinforced plastic may contain, for example, glass fibers, aramid fibers and / or preferably carbon fibers. The jacket 28 may thus consist at least partially in particular of carbon fiber reinforced plastic (CFRP).

FIG. 3 shows a schematic section of the jacket 28 of an embodiment of the flow-through cylinder 12 made of several individual parts.

The jacket 28 comprises circumferentially extending, in particular annular, webs 38 and extending in the axial direction webs 40th

In this case, for example, such a structure is conceivable in which the circumferentially extending webs 38 at least partially made of fiber-reinforced plastic whose fibers are oriented mainly in the circumferential direction, and extending in the axial direction webs 40 at least partially made of metal and preferably with recesses 42 for the are provided in the circumferential direction webs 38. The circumferentially extending webs 38 may with the in.

Axially extending webs 40 be glued. The axially extending webs 40 may be associated with a floating bearing.

However, it is also possible, for example, such a structure in which both the circumferentially extending webs 38 and the axially extending webs 40 each consist at least partially of fiber reinforced plastic and the circumferentially extending webs 38 and extending in the axial direction webs 40 form fit with each other connected and preferably glued together.

In the latter case, the fibers are preferably oriented in the circumferential direction in the circumferential direction webs 38, preferably in the circumferential direction and the fibers in the axially extending webs 40 in the axial direction.

The jacket 28 may be provided with quadrangular, in particular square or preferably rectangular passage openings 36, which may be formed in the present case between the webs 38, 40.

The height of the circumferentially extending webs 38 is indicated in Fig. 3 with hu and the height of the axially extending webs 40 with h _a . As already mentioned, these heights hu and h _{a can be the} same size or different. For example, the axially extending lands 40 may be taller than the circumferentially extending lands 38. To increase the flexural rigidity, the heights h _{a of} the axial lands 40 may be greater than about 100 mm, preferably greater than about 200 mm. Are the axially extending webs 40 with respect to the circumferentially extending webs 38th radially outward, the flow-through sieve 14 (see Fig. 1) rests on the webs 40 running in an axial direction. However, it is also conceivable that both extending in the circumferential direction webs 38 and the axially extending webs 40 terminate in the circumferential plane, so that the Durchströmsieb 14 rests on the circumferentially extending webs 38 and the axial webs 40.

4 shows a schematic section of the jacket 28 of an embodiment of the flow-through cylinder 12, in which the jacket 28 consists of layers of fiber-reinforced plastic produced in particular by the winding process and with, for example, round, square and / or rectangular through openings 36 in the present case is provided. To equalize the flow connecting channels between adjacent holes or openings can be provided.

As can also be seen in particular with reference to FIG. 5, which shows a schematic section through the cylinder jacket 28 shown in FIG. 4, the passage openings 36 can be countersunk.

In FIG. 5, the outer radius of the jacket 28 is indicated by "r _a " and the inner radius by "r _i ". The radial thickness of the shell 28 is designated "r _M ". This can be in particular ≥ 100 mm and preferably ≥ 200 mm.

LIST OF REFERENCE NUMBERS

10

Through air drying system

12

throughflow

14

Durchströmsieb

16

Hood

18

management

20

burner

22

suction box

24

management

26

management

28

coat

30

frontal lid

32

vent

34

pivot

36

Through opening

38

in the circumferential direction web

40

axially extending web

42

recess

h _a

Height of an axially extending web

h _U

Height of a circumferential web

r _a

Coat outer diameter

_i

Coat inside diameter

r _M

shell thickness

Claims (28)

1. Through-flow cylinder (12) at least partly composed of fibre-reinforced plastic for a through-flow drying unit (10), in particular for tissue,
   characterized in that
   it comprises webs (38) running in the circumferential direction, in particular annular webs, and webs (40) running in the axial direction, the webs (38) running in the circumferential direction being at least partly composed of fibre-reinforced plastic whose fibres are primarily oriented in the circumferential direction, and the webs (40) running in the axial direction being at least partly composed of metal and preferably being provided with cut-outs (42) for the webs (38) running in the circumferential direction.
2. Through-flow cylinder according to Claim 1, characterized in that the material of the fibre-reinforced plastic contains glass fibres, aramide fibres and/or preferably carbon fibres (CRP).
3. Through-flow cylinder according to Claim 1 or 2, characterized in that the matrix material of the fibre-reinforced plastic is composed of a material that is preferably heat-resistant at least to 300°C, for example resin.
4. Through-flow cylinder according to one of the preceding claims, characterized in that at least one fibre layer is provided and in that the fibre layer is chosen in such a way that the thermal expansion coefficient α of the fibre-reinforced plastic is less than that of steel at about 300°C and preferably lies in a range 0 ≤ α ≤ 9 · 10^-6 1/Kelvin.
5. Through-flow cylinder according to one of the preceding claims, characterized in that more than about 30%, in particular more than about 50% and preferably more than about 70% of the fibres of the fibre-reinforced plastic are oriented at least substantially in the circumferential direction.
6. Through-flow cylinder according to one of the preceding claims, characterized in that it has a diameter ≥ 2.5 m, in particular > 4 m and preferably> 4.5 m.
7. Through-flow cylinder according to one of the preceding claims, characterized in that at least its shell (28) is at least partly composed of fibre-reinforced plastic, preferably carbon fibre-reinforced plastic (CRP).
8. Through-flow cylinder according to Claim 7, characterized in that the webs (38) running in the circumferential direction are adhesively bonded to the webs (40) running in the axial direction.
9. Through-flow cylinder according to Claim 7 or 8, characterized in that it is provided with a loose bearing.
10. Through-flow cylinder according to one of the preceding claims, characterized in that the webs (40) running in the axial direction are also in each case at least partly composed of fibre-reinforced plastic, and in that the webs (38) running in the circumferential direction and the webs (40) running in the axial direction are connected to one another by a form fit and preferably adhesively bonded to one another.
11. Through-flow cylinder according to Claim 10, characterized in that the fibres in the webs (38) running in the circumferential direction are oriented in the circumferential direction, and the fibres in the webs (40) running in the axial direction are oriented in the axial direction.
12. Through-flow cylinder according to Claim 10 or 11, characterized in that its shell (28) is provided with four-cornered, in particular square or preferably rectangular, passage openings (36).
13. Through-flow cylinder according to Claim 12, characterized in that the passage openings (36) are formed between the webs (38, 40).
14. Through-flow cylinder according to Claim 12 or 13, characterized in that the open area lies in a range from about 95% to 98%.
15. Through-flow cylinder according to one of the preceding claims, characterized in that the dimensions of a respective passage opening (36) are 60 mm x 120 mm.
16. Through-flow cylinder according to one of the preceding claims, characterized in that the webs (40) running in the axial direction are higher than the webs (38) running in the circumferential direction.
17. Through-flow cylinder according to one of the preceding claims, characterized in that both the webs (38) running in the circumferential direction and the webs (40) running in the axial direction end in the circumferential plane.
18. Through-flow cylinder according to one of Claims 1 to 16, characterized in that the webs (40) running in the axial direction project radially further outward as compared with the webs (38) running in the circumferential direction.
19. Through-flow cylinder according to one of the preceding claims, characterized in that it is covered with a mesh stocking, in particular with an open surface <96%.
20. Through-flow cylinder according to Claim 19, characterized in that the mesh stocking is composed of a material that is preferably heat-resistant at least to 250°C, for example metal.
21. Through-flow cylinder according to one of the preceding claims, characterized in that its shell is composed of layers of fibre-reinforced plastic produced in particular in accordance with the winding process and is provided with, for example, round, square and/or rectangular passage openings.
22. Through-flow cylinder according to one of the preceding claims, characterized in that the fibres have a smaller thermal expansion coefficient than the plastic, at least in one direction.
23. Through-flow cylinder according to one of the preceding claims, characterized in that it comprises segments which are in particular adhesively bonded and/or screwed together.
24. Through-flow cylinder according to one of the preceding claims, characterized in that it comprises individual, in particular short, cylindrical sections which are preferably adhesively bonded or screwed together.
25. Through-flow cylinder according to one of the preceding claims, characterized in that the webs running in the axial direction and the webs running in the circumferential direction have apertures.
26. Through-flow cylinder according to one of the preceding claims, characterized in that the heights (h_a) of the webs (14) running in the axial direction are greater than about 100 mm and preferably greater than about 200 mm.
27. Through-flow cylinder according to one of the preceding claims, characterized in that connecting channels are provided between adjacent passage openings or holes.
28. Through-flow cylinder according to one of the preceding claims, characterized in that the radial thickness (r_M) of the shell (28) is ≥ 100 mm and preferably ≥ 200 mm.

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