WO2003067106A1

WO2003067106A1 - A deflection compensated roll of a paper/board machine or finishing machine having a composite shell and a method for its manufacture

Info

Publication number: WO2003067106A1
Application number: PCT/FI2003/000084
Authority: WO
Inventors: Pekka Korpelainen; Jorma Snellman
Original assignee: Metso Paper Oy
Current assignee: Valmet Technologies Oy
Priority date: 2002-02-04
Filing date: 2003-02-03
Publication date: 2003-08-14
Anticipated expiration: 2004-08-04
Also published as: FI111185B; FI20020209A0; DE10392182T5; AU2003201986A1; DE10392182T8

Abstract

The invention relates to a deflection compensated roll (10) with composite shell, the roll comprising a stationary roll shaft (12) on which are arranged load elements (11), which exert a load on the inner surface of the composite shell (1), in the direction of the nip formed with the backing roll. On the inner surface of the composite shell (1) is a thin coating layer (3), which extends in the axial direction of the shell (1) at least over the axial length (L) determined by the load element (11).

Description

A deflection compensated roll of a paper/board machine or finishing machine having a composite shell and a method for its manufacture

The present invention relates to a composite shell deflection compensated roll of a paper/board machine or finishing machine, the roll forming a nip with the backing roll. Applications may include, for example, the nip rolls of the press section and the calender. The roll comprises a stationary roll shaft, on which is arranged at least one load element, which exerts the load on the inner surface of the composite shell, in the direction of the nip formed with the backing roll. The invention also relates to a method for making a composite shell deflection compensated roll.

One problem with deflection compensated composite shell rolls is the difficulty of accomplishing a sufficiently long service life, which is due to the relatively poor durability of the composite shell against the oil pressure caused by the load element. The high oil pressure exerted on the inner surface of the shell may cause the oil to penetrate through the shell or the structure to become delaminated. The composite shell also will not withstand the mechanical contact of the load elements if the lubricating film fails - the surface hardness of the composite shell is not very good - and thus the inner surface of the shell is susceptible to scratching and wear.

Accordingly, one aim of the present invention is to provide an improved deflection compensated roll with composite shell, which will eliminate or minimise the above-mentioned problems of prior art composite shells. To achieve this aim, the deflection compensated roll according to the invention is characterised in that on the inner surface of the composite shell is a thin coating layer containing metal and/or ceramic, the said layer extending in the axial direction of the shell at least over the axial length determined by the said at least one load element. The method according to the invention is characterised in that in the method is used a mould, around which is mounted a thin inner shell part of metal, which adopts the shape of the mould, onto which inner shell part is made an outer shell part of thicker composite material, after which the shell is removed from the mould.

A method according to a second aspect of the invention for making a deflection compensated roll with composite shell is characterised in that, in the method, the composite shell is formed on a mould, the shell is removed from the mould and the inner surface of the shell is coated with a coating containing metal or ceramic. Coating may take place electrochemically using a metal coating, for example, chromium or copper, or by thermal spraying a metallic or ceramic coating, such as a coating containing one or more of the following substances: aluminium, wolfram carbide, cobalt, chromium and nickel.

A method according to a third aspect of the invention is characterised in that, in the method, a layer of mass containing ceramic and/or metal is spread onto a mould, a reinforcing layer is spread onto the mass layer, and onto the reinforcing layer is spread a new mass layer containing ceramic and/or metal, and after this, a fibre-reinforced layer of desired thickness is made onto the reinforced mass layer, and once the composite shell thus formed has cured, the shell is removed from the mould. The fibre-reinforced layer is preferably made by winding.

The invention is described in greater detail in the following, with reference to the Figures in the accompanying drawing, in which:

Figure 1 shows diagrammatically a deflection compensated nip roll with composite shell according to the prior art, Figure 2 shows a composite shell made according to the invention as a diagrammatic partial section,

Figure 3 shows a partial sectional view of the mould used in the method according to the invention,

Figure 4 shows diagrammatically a prior art manufacturing method applied to the method according to the invention for forming a fibre-reinforced shell.

The prior art deflection compensated nip roll 10 with composite shell 1 shown diagrammatically in Figure 1 comprises a stationary centre shaft 12 provided with load elements 11 loading the shell 1 in the direction of the nip. By composite is referred to a structure comprising reinforcing fibres, for example, carbon, boron or glass fibres or their mixtures which may extend in the longitudinal direction of the shell and/or the circumferential direction, and a matrix material which may be polymeric, ceramic or metallic. Ceramic material includes various oxides and carbides, for example, Al, B, Cr, Ti, Si, Sn, W, Zn, Zr oxides and carbides and their mixtures, and different nitrides,

Figure 2 shows an enlarged partial view of a composite shell 1 made in accordance with the invention, the inner surface of which shell is provided with a metal coating 3, which may consist of, for example, steel band or sheet, the said band or sheet being placed around a mould 6 (Figure 3) and welded to form the steel shell part around which is made a thicker outer layer of composite material by laminating or winding, and after this the shell is removed from the mould 6. In Figure 2, reference numeral 4 refers to a bond piece by means of which the shell 1 has been fixed to the end cover and fitted rotatably with bearings on the shaft 12. The thickness of the steel band or sheet is preferably about 1 to 1.5 mm, most preferably about 1.1 to 1.2 mm. The coating may also be, for example, an electrochemically made coating, in which case a shell of composite material is made first, for example, by using a mould, and the inner surface of the shell is then coated with the desired metal coating. In Figure 2, reference numeral 2 denotes a polymer coating layer formed on the outer surface of the composite shell. The polymer coating layer may be made at the same stage with the making of the composite shell, or at a later separate stage. An electrochemical coating requires that the matrix is made electrically conductive or the surface is treated with electrically conductive paint.

The coating layer on the inner surface of the composite shell may also consist of a mass containing ceramic and/or metal, which may comprise several mass layers, between which is a reinforcing layer that may be, for example, glass fibre mat. This type of coating layer consisting of ceramic and/or metal is preferably made by spreading the first mass layer containing ceramic and/or metal onto the mould, onto which mass layer is spread a reinforcing layer and onto that is spread a new mass layer containing ceramic and/or metal. These stages may be repeated several times to form a mass containing ceramic and/or metal of desired thickness on the mould. The layer of mass containing ceramic and/or metal may be made by mixing ceramic and metal particles and resin (e.g. epoxy) and/or release agent. As a release agent could be used, for example, aramid, graphite, or molybdenum sulphide.

After this, a layer of reinforcing fibre of desired thickness is wound onto the reinforced mass layer, and this is allowed to cure. Once the composite shell has cured, the shell is removed from the mould. During the heating required by curing, the mould expands more than the composite shell, whereby a gap forms between them during cooling. The gap thus formed may be utilised for removing the shell from the mould by using water, which is fed into the said gap to facilitate the removal of the shell.

Figure 4 shows diagrammatically a prior art arrangement applied to the method according to the present invention for making a composite shell. Fibre thread 41 is wound from a reel 40 through a bath forming the composite structure of the matrix in a vessel 44 to a guide device 42 arranged to reciprocate along a guide bar 43 for winding the fibre thread on the shell part 1. The bath in the vessel 44 may consist of, for example, epoxy resin, phenolic resin or polyamide. The shell part may be comprised of, for example, a metal shell part 3 (Figure 3) formed around a mould 6 or a mass layer containing ceramic formed on the mould, the said mould and its coating layer being arranged to rotate during the winding of the fibre thread. The fibre thread may be wound in different layers 41a, 41b, in different angular positions with respect to the axis of rotation 45, whereby the desired strength is obtained for the shell part. In the example case shown in Figure 4, the angle of winding in each layer 41a and 41b is about 45° with respect to the axis of rotation 45, but their opening directions are mutually opposite, which means that the angle between the layers 41a and 41b will be about 90°.

Depending on the type of bearing, the width of the coating layer 3 should be somewhat wider than the axial length L determined by the load element/elements 11, or preferably the length of the entire shell. A composite shell is preferably made excessively long and subsequently cut to final length, and the end pieces are fixed to it by using an adhesive.

Claims

1. A composite shell deflection compensated roll (10) of a paper/board machine or finishing machine, the roll comprising a stationary roll shaft (12) on which is arranged at least one load element (11), which exerts a load on the inner surface of the composite shell (1), in the direction of the nip formed with the backing roll, characterised in that on the inner surface of the composite shell (1) is a thin coating layer (3) of metal and/or ceramic, the said layer extending in the axial direction of the shell (1) at least over the axial length (L) determined by the said at least one load element (11).

2. A deflection compensated roll as claimed in claim 1, characterised in that the thickness of the coating layer is approximately 0.1 to 1.5 mm.

3. A deflection compensated roll with composite shell as claimed in claim 1 or 2, characterised in that the thickness of the coating layer is approximately 1.1 to 1.2 mm.

4. A deflection compensated roll with composite shell as claimed in any of the claims 1 to 3, characterised in that the coating layer is a metal shell part (3) on the inner surface of which is formed a protective layer, preferably of the same composite material as the outer shell part.

5. A deflection compensated roll with composite shell as claimed in any of the claims 1 to 4, characterised in that the composite shell is formed of thin steel band or sheet, which is formed on a mould (6) into a steel shell part (3), and on which steel shell part (3) is laminated a thicker outer shell part of composite material.

6. A deflection compensated roll with composite shell as claimed in any of the claims 1 to 4, characterised in that the composite shell is formed of thin steel band or sheet, which is formed on a mould (6) into a steel shell part (3), on which is formed by winding a thicker outer shell part of composite material.

7. A deflection compensated roll with composite shell as claimed in any of the claims 1 to 4, characterised in that the composite shell is formed of a mass mainly containing ceramic, which is first spread on the surface of the mould, and on which mass is formed by winding a layer of composite material of desired thickness.

8. A deflection compensated roll with composite shell as claimed in claim 7, characterised in that resin and/or release agent is mixed in the layer of mass containing ceramic.

9. A deflection compensated roll with composite shell as claimed in claim 7 or 8, characterised in that the layer of mass containing ceramic is comprised of at least two partial layers between which is a reinforcing layer.

10. A method for making a deflection compensated roll with composite shell, the roll comprising a stationary roll shaft (12) on which is arranged at least one load element (11), which exerts the load on the inner surface of the composite shell (1), in the direction of the nip formed with the backing roll, characterised in that in the method is used a mould (6), around which is mounted a thin inner shell part (3) of metal, onto which is laminated a thicker outer layer of composite material, after which the shell is removed from the mould.

11. A method for making a deflection compensated roll with composite shell, the roll comprising a stationary roll shaft (12) on which is arranged at least one load element (11), which exerts the load on the inner surface of the composite shell (1), in the direction of the nip formed with the backing roll, characterised in that in the method is used a mould (6), around which is mounted a thin shell part (3) of metal, onto which is formed by winding a thicker outer layer of composite material, after which the shell is removed from the mould.

12. A method as claimed in claim 10, characterised in that on the inner surface of the metal shell part (3) is made a protective layer, preferably of a composite material corresponding to that of the outer layer.

13. A method as claimed in any of the claims 10 to 12, characterised in that the metal band (3) used in the method has a thickness of approximately 1 to 1.5 mm, preferably about 1.1-1.2 mm.

14. A method as claimed in any of the claims 10 to 13, characterised in that the metal shell part (3) is made by winding thin metal band onto the mould (6) and by joining the band into an solid shell part by welding the seam between the edges of the band so as to close it.

15. A method as claimed in any of the claims 10 to 13, characterised in that the metal shell part is made of thin steel sheet, which is bent around a mould (6), and the seam (5) formed between the ends of the plate is welded to close it.

16. A method for making a deflection compensated roll with composite shell, the roll comprising a stationary roll shaft (12) on which are arranged load elements (11), which exert a load on the inner surface of the composite shell (1) in the direction of the nip formed with the backing roll, characterised in that in the method, the composite shell is formed on a mould, the shell is removed from the mould and the inner surface of the shell is coated with a coating layer containing metal and/or ceramic.

17. A method as claimed in claim 16, characterised in that the coating layer is made electrochemically as a metal coating.

18. A method as claimed in claim 16, characterised in that the coating layer is made by thermal spraying.

19. A method for making a deflection compensated roll with composite shell, the roll comprising a stationary roll shaft (12) on which are arranged load elements (11), which exert a load on the inner surface of the composite shell (1), in the direction of the nip formed with the backing roll, characterised in that in the method, a layer of mass containing ceramic and/or metal is spread onto a mould, a reinforcing layer is spread onto the mass layer, and onto the reinforcing layer is spread a new mass layer containing ceramic and/or metal, and after this, a fibre-reinforced layer of desired thickness is made on the reinforced mass layer, and once the composite shell thus formed has cured, the shell is removed from the mould.

20. A method as claimed in claim 19, characterised in that glass fibre mat is used as the reinforcing layer.

21. A method as claimed in claim 19, characterised in that the composite material layer is made by winding.