EP1687479A1

EP1687479A1 - Method for reinforcing the structures of manufacturing or finishing devices of a paper web

Info

Publication number: EP1687479A1
Application number: EP04818842A
Authority: EP
Inventors: Tomi Norrby; Reijo Hassinen; Jukka T. Heikkinen; Marko Maja; Matti Pajala
Original assignee: Metso Paper Oy
Current assignee: Valmet Technologies Oy
Priority date: 2003-11-21
Filing date: 2004-11-18
Publication date: 2006-08-09
Anticipated expiration: 2024-11-18
Also published as: JP4594323B2; EP1687479B1; ATE524605T1; WO2005049919A1; JP2007511678A

Abstract

Method for reinforcing the structures of manufacturing or finishing devices of a paper web or the like. The structures are box beam structures (2, 15) or foundations (17, 18) of the manufacturing or finishing devices of a paper web or the like. The structures (2, 15, 17, 18) are reinforced by attaching at least one stiffening member (1) made of composite material on their outer surface.

Description

Method for reinforcing the structures of manufacturing or finishing devices of a paper web

Field of the invention

The invention relates to a method according to the preamble of the appended claim 1 for reinforcing the structures of manufacturing or finishing devices of a paper web or the like.

Background of the invention

The manufacture of a paper web or the like, such as a paperboard or tissue web takes place in a web manufacturing device, i.e. in a paper machine. Web manufacturing devices are divided into different stages according to their basic process, and/or treatment conducted for the web. These stages include for example a web formation stage containing for instance the headbox and the parts belonging thereto, a pressing stage containing the press and its rolls and wires/felts, a drying stage, a reeling stage, coating and calendering. The finished web is processed by means of finishing devices of the web, which include for example a coating apparatus and/or a calender, which may be located either as so-called on-line treatment devices in connection with the web manufacturing device before the machine reel-up, or they can be positioned after the machine reel-up as separate so-called off-line appa- ratuses. The finishing devices of the web also include a slitter-winder, which is typically located after the reel-up. All these apparatuses also include frame parts supporting the apparatuses.

The web produced in the papermaking machine and treated in the finishing apparatus is several meters, even 10 to 12 meters wide, and it is supported and treated in its cross direction with several rolls and other members while the web is moving forward in the apparatus. Thus, the paper machine contains several machine parts and supporting structures that are at least as wide as the web, often wider than the web. The large width of the web poses strict strength requirements for the elongated parts of the web manufacturing devices installed in the cross direction of the web. These include different elongated beams that serve different purposes. Non-restrictive examples of such cross direc- tion beams include for example doctor beams, measuring device beams, coating beams, tail cutter beams, washer beams, and parts of the frame of the machine, not excluding, however, the other beam positions in any way. Furthermore, the high running speed of a modern paper machine that can be as high as 1200 to 2000 meters per minute, as well as especially in the reel-up the production of heavier machine rolls set demands for the elongated parts and other parts in the frame of the machine. Calenders and reel-ups also contain parts that are long in the height direction of the machine, the strength of said parts having to endure a great deal because of the above-mentioned requirements. The above-mentioned beams and parts of the frame are usually box beam structures made of steel. They can also be made for example of constructional steel, stainless/acid-proof steel, or possibly also from a composite material. Thus, it is at present an aim to make the parts of the machine stronger than before so that it would be possible to meet the strength requirements. This results in utilization of stronger and thicker steel structures and other corresponding structures which are expensive and heavy increase the investment costs of the paper machine and cause problems for the durability of the foundations.

Doctor blades are used for cleaning impurities, such as fibers attached on the surface of the roll for example by scraping the surface of the rotating roll by means of said doctor blade. In connection with the machine there is mounted on brackets a doctor beam having a blade holder attached to it. The blade to be loaded against the roll is fastened to the blade holder. The doctor beam obtains vibration excitation from the roll to be scraped or from other rolls in the vicinity. In a corresponding manner, in the case of actuators such as measuring devices and washers arranged in connection with other beams, a mass traversing in the cross-machine direction from side to side is supported by the beam, wherein corresponding vibration excitation can also be exerted on said mass. The vibrations may contain several frequencies summed to each other, of which at least one can be recognized as the primary excitation frequency.

In prior art, the aim has been to dimension such beams, especially the doctor beams according to the rotating frequency of the counter roll of the doctor beam or in general according to the running speed of the machine and the vibrations caused thereby in such a manner that the specific frequency of the beam is at least 20% above the rotating frequency of the roll. Typically exceeding of 20% is sufficient to cover the decrease in the specific frequency due to the mounting of the beam on brackets and the actuators and actuating devices attached on the beam. Thus, it is possible to avoid uncontrolled resonance vibration of the beam.

When the speed of the paper or paperboard machine is increased, the result is in many cases such a situation where the speed of rotation of the roll or the vibrations caused by the machine in general are increased close to the specific frequency of the doctor beam. This results in vibration problems.

In prior art it has been possible to solve this problem by changing the beam to a beam having higher specific frequency. In practice this means a beam with larger dimensions and a stronger structure. In several cases the placement of such a larger beam in existing machine structures is problematic due to the limited space.

Web manufacturing and finishing devices are typically mounted on a concrete foundation in a web manufacturing plant. When building the paper mill, separate foundations, i.e. concrete slabs are typically cast for different process stages, for example for the reel-up of the reeling stage or the calender of the calendering stage, and the different process parts are mounted on the support of said slabs so that as strong a foundation as possible is attained and the transfer of vibrations possibly produced in said process stage as a result of the opera- tion of the machine via the foundation to another process stage can be prevented. When paper machines are rebuild, the aim is to intensify the performance of the machine. Typically, certain components of the process stages are changed in the rebuilding, some components are added to the process stage or even the entire process stage is rebuild. If the aim is to increase the web speed, this means that the diameters of the rolls grow. This increases the mass of said process stage. This is also the case if components are added to the machine. The increase in the mass of the machine/process stage causes stress on the foundations and it is often necessary to reinforce them in connection with the rebuilding by installing a supporting pillar underneath the concrete slab in question in the rebuilding process. This is extremely difficult and causes various kinds of problems: the dust produced in connection with the work damages the machine parts, because the machine itself is not dismounted entirely in connection with the rebuilding process, the area of the reinforcement work is typically narrow, the work takes time and the labour costs are high.

In construction of bridges and houses it is known to use a band made of a composite material to reinforce the concrete structures. The composite band is utilized for reinforcement of concrete structures, such as bridge decks and intermediate floors that will be or have already been installed on the horizontal plane in finished constructions.

In web manufacturing devices problems are also caused by the vibrations caused by parts rotating and moving in different machine sections. If the vibrations increase too much, they cause marking on the web to be manufactured as well as uneven wearing of the parts of the machine.

To reduce the vibrations harmful for the manufacture of the web, a solution has been disclosed for example in the US patent 4,537,659 in which a dewatering element extending across the width of the wire section in a paper machine is reinforced by welding separate stiffening members inside the element. The drawback of this solution is that the used reinforcements make the dewatering element heavier than be- fore, which increases the stress exerted on the supporting structures of the element. Furthermore, the reinforcements must be fastened to the element at its manufacturing stage, as it is almost impossible to add them at a later stage.

US patent 6,197,112 discloses a solution for preventing the deflections caused by variations of temperature in a supporting beam of an elongated part of a paper machine, such as a doctor or a coating blade. According to the publication the supporting beam is manufactured of several elongated tubular profile elements attached together in the longitudinal direction, said profile elements being made for example of steel and/or a composite material. It is a problem of the solution according to the publication that it is difficult to attach several tubular elements together in such a manner that said structure is in balance, so that additional vibrations are not produced in said part of the process.

US patent 5,356,519 discloses a method for manufacturing the longitudinal, box-like supporting beam for a doctor or a coating blade en- tirely of a composite material. Such a structure is, of course, lightweight, but it is difficult to manufacture.

US publication 2002/0066173 discloses a solution for reinforcing the structure of a roll or a beam in a paper machine by means of a com- posite material. In the solution according to the publication the composite material is fastened inside a roll or a beam, in holes extending across the length of the same. The problem in this solution is that it is difficult to produce the holes to be made inside the long components and that it is difficult to fasten the composite material in said long holes.

Brief description of the invention

The aim of the present invention is thus to provide a method for reinforcing the structures of manufacturing or finishing devices of a paper web or the like, such as a paperboard or a tissue web, by means of which method the above-mentioned problems are solved. By means of the method it is possible to reinforce and stiffen the structures of manufacturing or finishing devices of a web easily and in a simple manner both when installing new machines and/or machine parts and when rebuilding or modernizing old machines.

To attain this purpose, the method according to the invention is primarily characterized in what will be presented in the characterizing part of the independent main claim 1.

The other, dependent claims present some preferred embodiments of the invention.

The invention is based on the idea, that at least one stiffening member made of a composite material is attached to the structures of the manufacturing or finishing devices of a web, on the outer surface of the same, said stiffening member reinforcing the structure by increasing the bending stiffness of the structure or the specific frequency of its vibrations. By means of the invention it is possible to attain significant economical savings as the expensive metal materials such as steel materials and/or concrete used in the devices and structures can be replaced with a composite stiffening member. Furthermore, the invention is also ecological, because it minimizes the consumption of materials necessary in the structures. Especially in rebuilding processes, the invention brings about savings in the material consumption, because by means of the invention it is possible to avoid the replacement of old structures with new structures having larger dimensions and greater weight.

One embodiment of the invention is to fasten at least one stiffening member made of a composite material to the box-beam structures of the manufacturing or finishing devices of paper at their construction stage. Thus, the amount of steel necessary for the frame and machine structures is reduced and the structures become lighter, wherein it is also possible to reduce the amount of concrete necessary for the foun- dations, thus attaining savings in material costs. At the construction stage, when the foundations are cast from concrete, it is also possible to add at least one stiffening member inside or on the surface of the concrete, wherein it is possible to reinforce the foundations and make them lighter in weight. When stiffening members are utilized in new structures, it is possible to manufacture the structures and components so that they are initially smaller in size, and the space required by them can be reduced because the stiffening member provides the structure with the required strength, and it is not necessary to manufacture the structure of heavy and space-occupying steel. Thus, the use of stiffening members makes it possible to design and build substantially smaller and lighter structures.

One embodiment of the invention is to fasten at least one stiffening member made of a composite material to the structures of the manufacturing or finishing devices of paper when the devices are rebuild or modernized. It is possible to fasten the stiffening members to the beam-like structures even without having to remove the beam from its place. In the modernizations or rebuildings parts of the process are replaced with new, often heavier parts, or new devices or parts are added to the structures. By means of stiffening members it is possible to easily reinforce the already existing concrete foundations of the aforementioned devices by fastening stiffening members easily on the outer surface of the foundations, either on the lower of upper surface. Thus, time-consuming reinforcement work of the foundations as well as the production of dust resulting from the building work can be avoided. Furthermore, in rebuildings it is possible to reinforce the frame structures of steel extending in the travel direction of the web and the structures and parts extending across the width of the web by fastening at least one stiffening member on the existing structures and parts. By means of stiffening members it is in connection with rebuildings also possible to reinforce the cranes, primarily overhead cranes in the machine room of the manufacturing or finishing device of the web by fastening at least one stiffening member in the crane structures. Thus, it is possible to rapidly increase the capacity of the crane, and it is not necessary to replace the crane with a new one, which would be expen- sive. Especially the increasing size of the machine reels causes demand for this kind of reinforcement of the crane structures. By means of stiffening members it is also possible to affect the vibrations of the structures of the manufacturing or finishing devices of the web and to efficiently attenuate them. When the device is in use, pri- mary excitation frequency is exerted on these structures. In rebuildings it is possible to utilize the stiffening members to increase the specific frequency of the vibrations of the frame parts and the beams extending across the web in the device during the use in such a manner that it exceeds the primary excitation frequency. It is also possible to increase the specific frequency of the foundations by means of stiffening members. The specific frequency of the vibrations of complex steel structures composed of several parts can be adjusted on a suitable level or dynamically inaccurately dimensioned structures can be repaired by means of stiffening members. The adjustment takes place by measur- ing the vibrations of the frame or a part of the machine by means of a vibration sensor, the results of which will be processed by means of a mode analysis and on the basis of said analyses, a suitable amount of supporting profile is fastened to a suitable location in the structure. Thus, the use of stiffening members is a very fast and cost-efficient way to improve the specific frequency of the vibrations of the structures and components, as well as their resistance to stress.

To increase the specific frequency of the beams extending in the cross direction of the papermaking and finishing devices, such as doctor beams, at least one longitudinal stiffening member extending in the longitudinal direction of the beam is fastened on the outer surface of at least on one side of the beam. The stiffening member is fastened at least on that side of the beam that has substantially the weakest bending stiffness in the beam. The stiffness of the stiffening member may be for example 150 to 700 Gpa, advantageously 150 to 500 Gpa.

The fastening of the stiffening members to the structures of the machine also makes it possible to increase the speed of the machine. When the speed of the machine is increased, the rotating frequency of the rolls is increased and becomes close to the specific frequency of the vibrations of the structures of the machine. In other words, the vi- bration sensitivity of the structures increases. By stiffening the structures by means of stiffening members it is possible to increase the specific frequency of the vibrations on a sufficiently high level rapidly and in an affordable manner without having to replace the components of the machine.

The structure-reinforcing impact of the stiffening member is based on the fact that composite profiles have high tension-compression strength but relatively low bending stiffness. Thus, by fastening stiffening mem- bers in the structure, it is possible to transfer the bending of the structure into tension of the composite reinforcements, which tension is illustrated by means of arrows B in Fig. 4. Thus, the stiffening members both stiffen and reinforce the structure and increase its bending stiffness. The stiffness of the composite profile, i.e. modulus of elasticity can be even twice as high when compared to steel. The specific frequency f of the vibrations of beam complies with the following formula:

in which λ = is a constant value dependent on the support of the beam L = the length of the beam (m) E = modulus of elasticity of the stiffening member (Pa) I = square moment of the beam (m⁴) m = total mass of the beam (kg)

The addition of at least one stiffening member makes it possible to increase the specific frequencies of the vibrations of the beam without substantially increasing the mass of the beam. Similarly, when the ma- chine is rebuild for web wider than before, it is possible to reinforce the beam that is longer than before with a stiffening member, wherein less steel is required for the beam, and the structure is not only durable but also light-weight, and the specific frequencies of its vibrations are high. The composite material in use is advantageously a fiber-reinforced composite that typically comprises a fiber-reinforcement and a matrix. It is light in weight, lighter than the actual basic material of said part to be reinforced, such as steel or concrete. The composite material is for example carbon fiber composite in which the carbon fiber reinforcement is in a resin-epoxy matrix. When carbon fiber composites are used for reinforcing structures, it is possible to attain such values for the modulus of elasticity that are even higher than those of steel. The reinforcement can also be made of some other material whose modulus of elasticity properties are sufficiently high. Examples of other possible suitable materials that can be mentioned include PBZO (poly benzobisoxazole-1 ,4-phenylene), UHMWPE (Ultra High Molecular Weight Polyethylene) and different materials based on graphite fibers. In addition, certain aromatic polyamide fibers (for example KevlarTM) may be possible.

The stiffening members used in the invention can be manufactured for example by means of pultrusion, in which it is possible to affect the tension-compression strength of the stiffening member produced, thus producing stiffening members having different tension-compression strength, of which stiffening members it is possible to select a stiffening member suitable for the target in question. The tension-compression stiffness of the stiffening member to be produced is also affected by the quality of the fiber material used as well as its orientation in the matrix. The matrix, i.e. the epoxy-resin binds the fibers to a certain angle of orientation, and acts as a transmitter of forces. The stiffening member is fastened to the outer surface of the structure to be reinforced by means of a fastening agent, i.e. an adhesive, which can be made of the same material as the matrix of the stiffening member. Thus, when the matrix is made of epoxy-resin, the adhesive can be either resin or epoxy, or a mixture of these two.

The stiffening members to be used may have any possible shape, what is important, is that it can be easily fastened to the desired target. The stiffening members can be preformed profiles that follow the outer surface of the structure in question. It is advantageous to use thin, plate- like stiffening members that are rectangular or square-shaped or bandlike, and that are easy to handle. The stiffening member can also be made of several layers attached to each other. Furthermore, the stiffening member can also be arranged so that it has a smooth shape, to prevent accumulation of impurities.

Brief description of the drawings

In the following, the invention will be described in more detail with ref- erence to the appended drawings, in which

Fig. 1a shows a perspective view of a stiffening member used for reinforcing structures,

Fig. 1b shows a cross-section of a layered and smooth stiffening member used for reinforcing structures,

Fig. 1c shows a cross-section of a second smooth stiffening member used for reinforcing structures,

Fig. 2 shows a cross-section of a doctor beam that is reinforced according to the invention,

Fig. 3 shows a cross-section of a second doctor beam that is re- inforced according to the invention,

Fig. 4 shows the beam of Fig. 2 in a perspective view,

Fig. 5 shows a schematical perspective view of a calender re- inforced according to the invention, and

Fig. 6 shows a schematical perspective view of a foundation of manufacturing or finishing devices of a paper web reinforced according to the invention. In Figs. 1a to 6, the same numerals refer to corresponding parts and they will not be explained separately later on, unless required by the illustration of the subject matter.

Detailed description of the invention

In this context the structures of the manufacturing or finishing devices of a web refer to the frame structures of said device, especially structures that are long in the lateral, longitudinal and height direction, sup- porting structures, elongated beams extending across the width of the web in the above-mentioned devices or foundations of said device.

Fig.1a shows a perspective view of a section of a supporting profile i.e. a stiffening member 1 made of a composite material and used for re- inforcing structures. The stiffening member 1 is an elongated, band-like profile whose height, i.e. thickness t is for example 2 to 20 mm, advantageously 3 to 12 mm, and the width w for example 30 to 150 mm, advantageously 30 to 100 mm. The advantageous thickness of the stiffening member may be determined on the basis of the increase in the desired specific frequency that can be for example 5 to 30%.

Reasonable width of the stiffening member 1 can in its maximum be for example half of the width of that side of the box beam to which it is fastened. If the stiffening member 1 is too wide, it may cause handling problems for example when installing the stiffening member 1 , because for example a stiffening member made by means of a pultrusion process only contains longitudinal reinforcement fibers. Because of this the stiffening member 1 may tear easily in the cross direction. The length of the manufactured band-like stiffening member may vary, and at the installation stage it is easy to cut lengths therefrom that are suitable for each component to be reinforced.

The stiffening member 1 can also be formed of at least two carbon fiber composite strips attached to each other for example by means of glueing. Such an embodiment of the structure of the stiffening member is shown in Fig. 1b in which there are three strips on top of each other, to which reference is made with reference numerals 7, 8 and 9. The total thickness of the layers of the stiffening member thus produced lies within the limits determined for the thickness of the stiffening member as presented above. The stiffening member formed by the strips is at- tached to the beam by means of glueing 10.

Figs 1b and 1c show examples of a smooth stiffening member used for reinforcing structures. The smooth shape of the stiffening members prevents the accumulation of impurities on the stiffening member 1. In Fig. 4a the smoothness is attained by arranging several stiffening member profiles 7 to 9 on top of each other on a beam 2, where the widest profile 9 is on the bottom, the widths of the profiles 8, 7 decreasing outward therefrom. The profiles 7 to 9 are arranged centrally with respect to each other in the lateral direction, wherein their edges form a smooth stepped shape.

In Fig. 1c the smooth shape of the stiffening member 1 is attained by providing the stiffening member with a pyramidal cross section. Different rounded and bevelled edges, and such edges in general that do not collect impurities are possible, as well as rounding of steep edges for example by means of a suitable filling compound.

The stiffness of the stiffening member 1 may be for example 150 to 700 GPa, or even more. The stiffness of the stiffening member 1 to be at- tached to the beam 2 to be reinforced is selected in a manner most suitable for the situation in question. The criteria of the selection process may be determined for example on the basis of the stiffening need of the beam in question and on the other hand also on the basis of the price of the stiffening member. One criterion for an advanta- geous stiffness of the stiffening member is the modulus of elasticity of the beam 2 itself, which in the case of a box beam made of steel is in the order of 200 GPa. Thus, one example of an advantageous value for the modulus of elasticity of the stiffening member 1 can be 200 to 400 (500) GPa in its longitudinal direction, depending for example on the parameter of the beam 2 and its position. Fig. 2 shows a cross-section of the beam 2, in the reinforcement and stiffening of which it is possible to apply the method according to the invention. The beam 2 is a beam extending in the cross direction of a manufacturing or finishing device of a paper web or the like, across the width of the web. As can be seen in Fig. 2, the beam 2 is a box beam that is reinforced by attaching, typically welding the element bent in shape that forms the sides 4, 5 and 6 of the beam to the plate-like side 3 forming one side of the beam. Corresponding box beams are also used in the frame parts of manufacturing or finishing devices of a web. It is also possible that the box beams are formed by welding four platelike sides together. The method according to the invention can also be applied in this kind of a box beam.

In the example of Fig. 2 the box beam 2 is an elongated doctor beam having a doctor 11 attached to one of its corners. The doctor 11 can be formed of a blade holder known as such and a blade arranged in connection with the same, by means of which the surface of the roll 12 rotating against the blade is scraped. Vibration excitation is transferred from the roll 12 to the beam 2 via the blade and the holder 11 , as a re- suit of which the specific frequency of the beam 2 should advantageously be above the excitation frequency produced by the machine.

At least one stiffening member 1 is fastened to the beam 2, on the outer surface of at least one side 3, 4, 5 and 6 of the same. If the stiffening member has an elongated shape, it is advantageously fastened to the beam 2 in parallel to the longitudinal direction of the beam 2. According to a preferred embodiment the stiffening member 1 is fastened to the beam 2 substantially according to the direction determined by its weakest bending stiffness that corresponds to the stiffening member 1 arranged on the side 3 of the beam in Fig. 2. In addition to this direction, in the beam shown in Fig. 2 there is one stiffening member 1 on each side 4 to 6 of the beam. The elongated stiffening members 1 fastened to a selected location on the sides 3, 4, 5 and 6 of the beam increase the specific frequency of the beam when compared to the basic beam that does not have stiffening members. The fastening location of the stiffening member 1 to the sides 3 to 6 of the beam 2 can be determined for example on the basis of calculatory studies or knowledge based on experience.

Figs 3 and 4 show another doctor beam reinforced according to the invention. Here, two band-like stiffening members 1 are fastened on both sides 3 to 6 of the beam 2 in the longitudinal direction of the beam. The stiffening members are now close to the corners of the beam 2. The figures also show the bracketing shaft 13 of the beam in which the beam 2 is supported at its ends. Reference to Figs 3 and 4 will also be made at a later stage in the form of a calculation example.

It is also possible to provide the stiffening member 1 with a securing arrangement 14 shown in Fig. 2 to ensure the fastening of the stiffening member to the beam 2. The securing arrangement can be formed for example of bonds extending across the stiffening member and being arranged crosswisely across the stiffening member, said bonds ensuring the adhering of the stiffening member 1 on the outer surface of the beam 2. There may be one or several bonds arranged in the same stiffening member in the longitudinal direction of the beam 2. The bonds 14 secure the stiffening member 1 in its place, wherein the need for subsequent fastening of the stiffening members 1 is substantially reduced, which is typically difficult to perform in the narrow positions of the beams 2, and in general when the machine is running.

Fig. 5 shows a calender used in the finishing process of paper or paperboard, in this case a supercalender, in which stiffening members 1 have been fastened to reinforce its frame structures. The stiffening members can also be used for reinforcing the frame structures of other calender models. The frame 15 of the calender is made of housing structures made by welding constructional steel, in which housing structures rolls of the calender as well as most of the other parts and actuators of the calender are attached. The calender is a tall structure that is reinforced by fastening stiffening members 1 thereto at fixed intervals in the longitudinal direction of the frame with respect to the width of the frame. The stiffening members are fastened behind the frame, i.e. on the opposite side with respect to the calender rolls, and they extend on the entire height of the frame, all the way from the bottom to the top. This way the frame has been reinforced in its height direction. By means of supporting profiles it is possible to reinforce the frame of the calender also in its lateral direction by fastening stiffening members thereto substantially horizontally at fixed intervals within the entire height of the frame.

Fig. 5 also shows a roll change crane 16 used in the change of the calender rolls, the rail of said crane extending in the travel direction of the web being reinforced with at least one stiffening member 1.

Fig. 6 shows the reinforcement of the foundations of a manufacturing and finishing device of a web by means of stiffening members 1. In the figure the calender 15 is mounted on a separate concrete slab 17 that has been reinforced by fastening stiffening members 1 at fixed intervals on the upper surface of the slab 17. The stiffening members 1 can be fastened to the foundations also on the lower surface of the foundations, or inside the concrete at the casting stage. The fastening direction of the stiffening members with respect to the travel direction of the web is selected according to the foundation to be supported and the devices installed thereon as well as on the basis of the vibrations to be attenuated. The figure also shows a separate concrete foundation 18 of the preceding process stage.

The invention is not intended to be limited to the embodiments presented as examples above, but the invention is intended to be applied widely within the scope of the inventive idea as defined in the appended claims.

Claims

1. A method for reinforcing the structures of manufacturing or finishing devices of a paper web or the like, characterized in that the structures are box beam structures (2, 15) or foundations (17, 18) of manufacturing or finishing devices of a paper web or the like and that the structures (2, 15, 17, 18) are reinforced by fastening on their outer surface at least one stiffening member (1) made of a composite material.

2. The method according to claim 1 , characterized in that the composite material is a carbon fiber composite, containing carbon fibers as a reinforcement and epoxy-resin as a matrix.

3. The method according to claim 1 , characterized in that the box beam structures (2, 15) are frame structures (15) extending in the longitudinal or vertical direction of the manufacturing or finishing devices of a paper web or the like, and/or beams (2) extending in the cross direction of the manufacturing or finishing device of a paper web or the like.

4. The method according to claim 1 , characterized in that the box beam structures (2, 15) are reinforced by fastening at least one stiffening member (1) made of a composite material on their outer sur- face, said stiffening member (1 ) stiffening the box beam structures (2, 15) to increase the specific frequency of their vibrations.

5. The method according to claim 1 , characterized in that the box beam structures (2, 15) are reinforced by fastening at least one stiffening member (1) made of a composite material on their outer surface, said stiffening member (1) reinforcing the box beam structures (12, 15) by increasing their bending stiffness.

6. The method according to claim 1 , characterized in that the box beam structures (2, 15) are reinforced at least to the direction the weakest bending stiffness of the box beam (2, 15).

7. The method according to claim 1 , characterized in that the box beam structures (2, 15) are reinforced by fastening at least one stiffening member (1) on the outer surface of at least one side (3, 4, 5) of the box beam structure (2, 15).

8. The method according to claim 1 , characterized in that the stiffening member (1) has an elongated band-like, plate-like or preformed shape.

9. The method according to claim 1 or 8, characterized in that the stiffness of the stiffening member (1) is 150 - 700 Gpa, advantageously over 200 Gpa.

10. The method according to claim 1 or 8, characterized in that the thickness of the stiffening member (1) is 2 to 20 mm, advantageously

30 to 100 mm.

11. The method according to claim 1 or 8, characterized in that the width of the stiffening member (1) is 30 to 150 mm, advantageously 30 to 100 mm.

12. The method according to claim 1 or 8, characterized in that the stiffening member (1) is formed of several layers (7, 8, 9) attached to each other.

13. The method according to claim 1 or 8, characterized in that the stiffening member (1) is provided with a smooth shape to prevent accumulation of impurities.

14. The method according to claim 1 or 8, characterized in that the stiffening member (1) is provided with a securing arrangement (14) to ensure the fastening of the stiffening member (1).

15. The method according to claim 1 , characterized in that the stiffening member (1) is fastened to the structures (2, 15, 16, 17, 18) by means of an adhesive.

16. The method according to claim 15, characterized in that the adhesive is one of the following: the matrix itself, one of the components of the matrix or epoxy glue.

17. The method according to claim 1 , characterized in that the foundations (17, 18) are reinforced by fastening stiffening members (1) inside the concreting.

18. The method according to claim 1 , characterized in that at least one stiffening member (1) is fastened to the structures when installing new manufacturing or finishing devices of a web or when rebuilding old manufacturing and finishing devices of a web.

19. The method according to claim 1 , characterized in that the box beam (2) is reinforced to increase its specific frequency, which box beam (2) supports an actuator or a device (11) located in connection with the manufacturing or finishing device for a paper web or the like, which manufacturing or finishing device for a paper web or the like during its run produces vibration at least on one primary excitation frequency, said vibration being transmitted to the box beam (2) whose specific frequency is above its primary excitation frequency, and that the box beam (2) is reinforced to increase its specific frequency by means of at least one stiffening member (1) fastened to a selected point.

20. The use of at least one stiffening member (1) made of carbon reinforced composite to reinforce an elongated box beam (2, 15, 16) in a manufacturing or finishing device of a paper web or the like.