ROLL, PARTICULARLY OF A PAPER, BOARD, TISSUE

OR FINISHING MACHINE, AND METHOD FOR

MANUFACTURING THE SAME

Description

Technical Field

The present invention relates to a roll, particularly of a paper, board, tissue or finishing machine, a roll for use in a paper, board, tissue or finishing machine, preferably in a paper finishing machine, and to a method for manufacturing the same.

Description of the Prior Art

A roll for a paper, cardboard or finishing machine is disclosed in, for example, WO 2006/037859 Al. More particularly, the roll is supported at its middle. Most preferably, the roll of WO 2006/037859 Al is used as a spreader roll or a calender fly roll in the paper or cardboard machine.

Rolls as mentioned above, which are supported at their middle are primarily used as lead rolls, spreader rolls and fly rolls in the paper industry. They feature deflection properties which are different from those of conventional rolls supported at the ends thereof. Hence, for example length differences between the edge and the middle section of the fabric can be compensated in this way, and it can be ensured that the fabric or the web will not be wrinkled by bending the roll into a bow form, away from the direction of approach (spreader roll) .

One method of providing the middle support is disclosed in, for example, DE 198 07 857 Cl. The object of the roll disclosed therein is seen in optimizing the shell surface of the roll such that it is free from square-edged changes of direction during the intended use of the roll when applying a load per unit area.

In DE 198 07 857 Cl, the roll comprises an outer roll body (an outer tube) and a support shaft (an inner tube) , wherein the outer roll body encloses the support shaft in a predetermined radial distance. The outer roll body is supported by a supporting body which is arranged symmetrically to a theoretical radial plane intersecting the outer roll body axially and centrally. A sealing ring is arranged axially on both sides of the supporting body. The sealing rings contact an inner shell surface of the outer roll body and an outer shell surface of the support shaft under radial tension in a sealing manner. Between the sealing rings, the outer roll body has a hole for injecting resin material into an annular hollow space defined by the outer roll body, the two sealing rings and the support shaft. Thus, an adhesive connection between the outer roll body and the support body is achieved.

In general, the axial extension of the above described roll may be up to 6 meters or even longer. Thus, when assembling the roll, the outer tube has to be pushed over the inner tube over a distance of 6 meters, i.e. thus pushed over the sealing rings. Also, if a fixed and stable connection between the tubes is desired, the respective positioning portions should be press-fitted. That is, between the outer and inner tubes a clearance is formed by the sealing rings, and positioning of the tubes is ensured by the pressed sealing rings. Then, a portion (the annular hollow space) of the clearance is filled by injection resin material in

order to form a fixed and stable connection between the tubes .

Summary of the invention

The object of the present invention is to provide an improved roll and a method for manufacturing the same such that the roll can be easily and accurately assembled and a simple and stable connection between separate roll components is achieved.

This object is achieved by each of the feature combinations defined in the independent claims.

Presently preferred embodiments of the present invention are set forth in the dependent claims.

According to an aspect of the present invention, a roll, particularly of a paper, board (cardboard) , tissue or finishing machine, comprises an outer tube which encloses an inner tube, wherein the tubes comprise fitting portions being in radial and axial alignment with each other.

A roll according to the above aspect of the present invention can be easily and precisely assembled such that there is no unbalancing during the operation of the roll and thus a desired running smoothness of the roll for treating a web in a paper machine, preferably in a paper finishing machine, is achieved.

In accordance with a preferred embodiment of the present invention, the fitting portions are cooperating portions.

The roll according to the above preferred embodiment of the present invention ensures that the fitting portions are

cooperating such that the radial and axial positioning of the roll may be achieved.

In accordance with another preferred embodiment of the present invention, the fitting portions of the roll are fitting elements fixedly connected to the respective tubes.

In accordance with another preferred embodiment of the present invention, the fitting elements may further comprise a radial fitting section and an axial fitting section which are different from each other.

The roll according to the above preferred embodiments of the present invention ensures that the radial and axial alignment of the outer tube and the inner tube is achieved at different portions of the fitting elements. That is, the fitting elements have different fitting sections for radial alignment and axial alignment. Thus, the radial and axial positioning of the roll may be achieved more reliably and precisely.

In accordance with another preferred embodiment of the present invention, the fitting portions of the respective tubes are fixedly connected to each other.

The roll according to the above embodiment of the present invention has fitting elements which may be formed integrally with or may be stably fixed to the respective tubes. That is, the fitting elements can be made of the same or different materials as the tubes. Thus, a risk of damaging sealing rings used in the above-mentioned prior art by pushing the outer roll over the entire axial length of the inner roll in case of assembling the roll is avoided in the present invention. Thus, according to the invention, it can be ensured that the outer roll which encloses the

inner roll is easily mounted and that the outer roll is always in radial and axial alignment with respect to the inner roll .

In accordance with another preferred embodiment of the present invention, the fixed connection is constituted by a press fit connection, a form fit connection, or an adhesive j oint .

By the roll according to the above embodiment of the present invention, an easy and reliable connection between the inner and outer tubes is achieved. Further, the composition of the fixed connection ensures that a bulging of the roll, which works against the deflexion thereof, may be evenly arc-shaped in such a manner that at least the central portion of the roll is widely uniform. Thus, it is ensured that the specific area load is equal along the shell surface of the roll, which is contacting the web. Thus, different abrasive wear due to different specific surface pressures at the shell surface of the roll is reliably eliminated by the fixed connection.

In accordance with another preferred embodiment of the present invention, the adhesive joint is composed of resin material, preferably polymer material.

The roll according to the above embodiment of the present invention ensures that the composition of the adhesive joint is further improved with respect to its material properties. That is, a layer of the adhesive joint can be made very thin such that it is still adapted to absorb flexible deformations of the roll and to achieve a reliable connection between the respective tubes.

In accordance with another preferred embodiment of the present invention, the roll comprises a cavity which is formed between the radial fitting sections and the axial fitting sections.

The roll according to the above embodiment of the present invention ensures that, in this cavity, resin material can be injected and stably accommodated, so as to establish the adhesive joint between the inner and outer tubes. The resin material is not applied to the radial fitting sections and the axial fitting sections of the roll. Thus, a strict separation between alignment surfaces and fixing surfaces is achieved. Since the resin material cannot flow out of the cavity, the complete injection volume of the resin material may contribute to the fixing task. In contrast thereto, in the prior art, if the sealing rings, which are preferably made of silicone, are damaged during the assembly, the adhesive connection may be weak when portions of the injected resin material flow out of the annular hollow space, leaving bubbles or blow holes in the material .

In accordance with another preferred embodiment of the present invention, the outer tube and the fitting element comprise at least a hole for injecting resin material into the cavity.

In accordance with another preferred embodiment of the present invention, the cavity is circumferential with respect to the rotary axis of the roll.

In the roll according to the above embodiments of the present invention, the outer tube and the respective fitting element comprise at least an aperture (the hole) for injecting adhesive resin material into the cavity which

is defined by the radial fitting sections and the axial fitting sections of the respective fitting elements of the tubes. Preferably, the aperture extends in the radial direction. After the outer tube and the inner tube are arranged such that they are in axial and radial alignment relative to each other, they form a pre-mountable unit. Then, the resin material is injected through the aperture into the cavity until it is completely filled.

Further, another aperture for sucking off surplus adhesive material may be provided, through which the adhesive resin material flows out, and which is arranged on the outer shell surface of the outer tube opposite to the aperture for injecting. The adhesive material may be sucked off by a sucking means, and the sucking means is preferably a suction pump with negative pressure.

Following the hardening of the adhesive resin material (that is, after the adhesive joint is completely formed), the outer tube is covered by a roll covering or the like which also covers the respective apertures so that they are flushly closed with respect to the outer shell surface of the outer tube. Thus, the roll is ready for use, wherein in that case the outer roll and the inner roll are permanently connected to each other by the hardened resin material.

According to another preferred embodiment of the present invention, the fitting portion of the outer tube is arranged at an inner surface of the outer tube, and the fitting portion of the inner tube is arranged at an outer surface of the inner tube.

According to another preferred embodiment of the present invention, the outer tube and the inner tube are made of fibre-reinforced plastic material.

According to another preferred embodiment of the present invention, the roll is a spreader or a calender fly roll.

Further, the roll according to the invention may be used in a paper, board, tissue or finishing machine, preferably in a paper finishing machine.

According to a further aspect of the present invention, a method for manufacturing a roll comprises the steps of pushing an outer tube over an inner tube so that the outer tube encloses the inner tube, and radially and axially aligning the tubes by means of fitting portions with each other .

In accordance with the above aspect of the present invention, the manufacturing method of the roll ensures that the outer tube and the inner tube are in radial and axial alignment with each other by mutually contacting the fitting portions. Thus, the roll can be easily and precisely assembled such that there is no unbalancing during the operation of the roll and thus a desired running smoothness of the roll is achieved.

In accordance with a further preferred embodiment of the present invention, the radial and axial alignment step of the manufacturing method is achieved by the fitting portions which are fitting elements fixedly connected to the respective tubes and having a radial fitting section for radial alignment and an axial fitting section for axial alignment, the fitting sections being different from each other .

The manufacturing method according to the above preferred embodiment of the present invention ensures that the radial

and axial alignments of the outer tube and the inner tube are achieved independently from each other by the fitting elements which have different fitting sections for radial and axial fitting. That is, it is ensured that the radial and axial positioning of the tubes is achieved by the radial fitting sections and the axial fitting sections such that the radial and axial positioning of the tubes may be achieved more reliably and precisely.

In accordance with a further preferred embodiment of the present invention, the method further comprises the step of fixedly connecting the fitting portions to each other.

The manufacturing method according to the above preferred embodiment of the present invention ensures that the fitting elements are formed integrally with or are stably fixed to the respective tubes. That is, the fitting elements can be made of the same materials as the tubes, or of different ones. Thus, a risk of damaging sealing rings used in the prior art by pushing the outer roll over the entire axial length of the inner roll when assembling the roll is not possible in the present invention. Thus, according to the invention, it can be ensured that the outer roll which encloses the support shaft is easily mounted and that the outer roll is always in radial and axial alignment with respect to the inner roll.

Brief Description of the Drawings

The present invention will be described in greater detail below with reference to certain preferred embodiments illustrated in the accompanying drawings, to which the present invention is not to be exclusively confined. In the drawings,

Fig. 1 shows schematically a partial sectional view of a roll in accordance with the present invention;

Fig. 2 is an enlarged sectional view of a portion X in Fig. 1 showing a first embodiment of the present invention;

Fig. 3 is an enlarged sectional view of a portion X in Fig. 1 showing a second embodiment of the present invention;

Fig. 4 is an enlarged sectional view of a portion X in Fig. 1 showing a third embodiment of the present invention;

Fig. 5 is an enlarged sectional view of a portion X in Fig. 1 showing a fourth embodiment of the present invention during assembly; and

Fig. 6 is an enlarged sectional view of the portion X in Fig. 5 showing the fourth embodiment of the present invention when assembled.

Description of the Preferred Embodiments

Fig. 1 shows a partial sectional view of a roll in accordance with the present invention. The roll comprises an outer tube 1 and an inner tube 2. The outer tube 1 encloses the inner tube 2 with a predetermined radial distance, wherein, in the axial direction of the roll, at a middle portion X of the tubes 1 and 2 sleeves 3, 4

(bushings, ring elements or the like) for radial and axial alignment of the tubes are connected to shell surfaces of the tubes 1 and 2, respectively. That is, the sleeves 3, 4 are fitting portions or fitting elements fixedly connected

(preferably, by means of injected adhesive material 11) to the respective tube 1 or 2, which ensure the radial and axial alignment of the tubes 1 and 2.

Fig. 2 is an enlarged sectional view of a portion X in Fig. 1 showing a first embodiment of the present invention. In the first embodiment of the present invention, identical parts are provided with the same reference numbers as shown in Fig. 1, increased by the value 100.

In Fig. 2, the outer sleeve 103 is connected to the inner shell surface of the outer tube 101 and is formed as an annular element (fitting element) . An inner sleeve 104 is connected to the outer shell surface of the inner tube 102 and is formed as an annular element (fitting element) .

The outer sleeve 103 is formed as a conical element stably fixed on the inner shell surface of the outer tube 101. In particular, the outer sleeve 103 has a constant inner diameter portion 105 and a conical inner diameter portion (fitting portion or conical portion) 107. The conical portion 107 extends from the constant inner diameter portion 105 to an end face of the outer sleeve 103 in the axial direction thereof (to the left side in Fig. 2) such that an inner diameter of the conical portion 107 at the end face of the outer sleeve 103 is longer than that of the constant inner diameter portion 105.

The inner sleeve 104 is formed as a conical element stably fixed on the outer shell surface of the inner tube 102. In particular, the inner sleeve 104 has a constant outer diameter portion 106 and a conical outer diameter portion (fitting portion or conical portion) 108. The conical portion 108 extends from the constant outer diameter portion 106 to an end face of the inner sleeve 104 in the axial direction thereof (to the right side in Fig. 2) such that an outer diameter of the conical portion 108 at the

end face of the inner sleeve 104 is smaller than that of the constant outer diameter portion 106.

Thus, the conical portion 108 of the inner sleeve 104 forms a corresponding structural counterpart to the conical portion 107 of the outer sleeve 103.

In the first embodiment as shown in Fig. 2, the sleeves 103 and 104 are separate components and are stably connected to the respective shell surfaces of the outer and inner tubes 101 and 102 by means of bonding, preferably gluing, or the like. The sleeves 103 and 104 are preferably made of fibre- reinforced materials, for example polymer materials.

Here, a manufacturing process of the roll is described below, which establishes a fixed and stable connection between the two tubes 101 and 102 as shown in Fig. 2.

Firstly, the outer tube 101 is pushed over the entire axial length of the inner tube 102 (i.e. in the present embodiment, the axial length of the entire roll is about 6 meters) . When the respective sleeves 103 and 104 arranged at respective shell surfaces of the tubes 101 and 102 get in contact with each other at the respective conical portions 107, 108, the axial and radial alignment between the inner tube 102 and the outer tube 101 is established. Thus, the outer tube 101 and the inner tube 102 form a pre- mounted unit in which the axial and radial alignment between the inner tube 102 and the outer tube 101 is established by contacting of the conical portions 107, 108 of the sleeves 103, 104.

Then, the outer tube 101 including the outer sleeve 103 is provided with an injection aperture (hole) 113 by drilling, which extends in the radial direction of the tube 101

through the conical portion 107 thereof. The injection aperture 113 may be formed before the tubes 101, 102 are assembled. The injecting of adhesive material 111 is further described below.

The adhesive material 111 (shown by the arrow pointing downwards in Fig. 2) is injected through the injection aperture 113 towards the contacting conical portions 107, 108 of the sleeves 103 and 104. The injected adhesive material 111 spreads over the contacting conical surfaces 107, 108 of the sleeves 103 and 104. Preferably, the adhesive material 111 is uniformly distributed and completely covers the contacting conical portions 107, 108 of the sleeves 103 and 104 along the circumferential direction thereof. The injection of the adhesive material 111 is then finished and ensures good adhesion between the respective portions which are radially and axially aligned to each other.

Then, the outer tube 101 is covered by a roll covering or the like, which also covers the aperture 113 after injecting of the adhesive material 111 is finished such that an outer shell surface of the outer tube 101 is uniformly and flushly formed.

Thus, after the complete hardening of the adhesive material 111, a fixed and stable connection between the outer and inner tubes 101 and 102 is established which withstands high rotational speed operations of the roll. Simultaneously, it is ensured that the inner and outer tubes 101 and 102 are axially and radially aligned so a sufficient running smoothness of the roll for treating a web in a paper machine is achieved.

Fig. 3 is an enlarged sectional view of a portion X in Fig. 1 showing a second embodiment of the present invention. In Fig. 3, the second embodiment according to the present invention essentially corresponds to the first embodiment shown in Fig. 2 so that only the differences will be described below. In Fig. 3, similar parts are provided with the same reference numbers as shown in Fig. 2, increased by the value 100. Moreover, the description of parts similar to those of the first embodiment is omitted. That is, only the structural differences of sleeves 203 and 204 with respect to the first embodiment are described.

In Fig. 3, the sleeve 203 of the outer tube 201 is formed as a stepped outer ring element 203 as a fitting element or ring element stably fixed on the inner shell surface of the outer tube 1, and the sleeve 204 of the inner tube 202 is formed as a stepped inner ring element 204 as a fitting element or ring element stably fixed on the outer shell surface of the inner tube 202. In particular, the ring elements 203, 204 are acting as fitting elements which are fixedly connected to the respective tubes 201, 202 and comprise radial fitting sections 207, 208 and axial fitting sections 209, 210, which are different from each other.

The stepped outer ring element 203 comprises a first diameter portion 205 and a second diameter portion 207, wherein the first diameter portion 205 has an inner diameter smaller than that of the second diameter portion 207. The stepped inner ring element 204 comprises a third diameter portion 208 and a fourth diameter portion 206, wherein the third diameter portion 208 has an outer diameter smaller than that of the fourth diameter portion 206. The second diameter portion 207 of the stepped outer ring element 203 corresponds to and faces the third diameter portion 208 of the stepped inner ring element 204.

The inner diameter of the second diameter portion 207 is substantially the same as the outer diameter of the third diameter portion 208.

Further, the stepped outer ring element 203 comprises a first step portion 209 between the first diameter portion 205 of the stepped outer ring element 203 and the second diameter portion 207 thereof. The first step portion 209 is substantially formed as a ring surface or annular flange perpendicularly arranged with respect to the rotational axis of the roll. The stepped inner ring element 204 comprises a second step portion 210 between the third diameter portion 208 of the stepped inner ring element 204 and the fourth diameter portion 206 thereof. The second step portion 210 is substantially formed as a ring surface or annular flange perpendicularly arranged with respect to the rotational axis of the roll.

Now, a manufacturing process of the roll is described in order to establish a fixed and stable connection between the two tubes 201 and 202 according to the second embodiment of the present invention as shown in Fig. 3.

Firstly, the outer tube 201 is pushed over the entire axial length of the inner tube 202 in the way described in the first embodiment of the present invention. When the respective ring elements 204, 203 get in contact to each other at the respective portions thereof, the axial and radial alignment between the inner tube 202 and the outer tube 201 is established. That is, the second diameter portion 207 of the stepped outer ring element 203 and the third diameter portion 208 of the stepped inner ring element 204 abut against each other for radial alignment of the tubes 201, 202, and the first step portion 209 of the stepped outer ring element 203 abuts against an end face of

the stepped inner ring element 204 and the second step portion 210 of the stepped inner ring element 204 abuts against an end face of the stepped ring element 203 such that axial alignment of the inner and outer tubes 201 and 202 is provided.

Then, the outer tube 201 including the stepped outer ring element 203 is provided with the injection aperture (hole) 213 by drilling, which extends in the radial direction of the tube 201 through the second diameter portion 207 in order to inject the adhesive material 211. This injection operation is identical to that of the first embodiment as described above. So, a further description thereof is omitted. Of course, the injection aperture 213 may be formed before the tubes 201, 202 are assembled.

After the hardening of the adhesive material 211 located between the outer and inner tubes 201 and 202 a fixed and stable connection (adhesive joint) for high rotational speed operations of the roll is established and is similar to that of the first embodiment shown in Fig. 2. Further, by tight abutment of the respective step portions 209, 210 against the end faces of the stepped inner ring element 204 and stepped outer ring element 203, respectively, it can be prevented that adhesive material leaks out of the adhesive joint region formed between the second diameter portion 207 and the third diameter portion 208 as mentioned above.

Fig. 4 is an enlarged sectional view of a portion X in Fig. 1, showing a third embodiment of the present invention. The third embodiment shown in Fig. 4 essentially corresponds to the second embodiment shown in Fig. 3. In Fig. 4, similar parts are provided with the same reference numbers as shown in Fig. 3, increased by the value 100. Moreover, the description of similar parts as shown in the above-

mentioned embodiment is therefore omitted. That is, only the structural differences of the constitution of sleeves

303 and 304 with respect to that of the above embodiment are mentioned below.

In Fig. 4, the sleeve 303 of the outer tube 301 is formed as a stepped outer ring element 303 stably fixed on the inner shell surface of the outer tube 301, and a sleeve 304 of the inner tube 302 is formed as the stepped inner ring element 304 stably fixed on the outer shell surface of the inner tube 301.

Similarly to Fig. 3, the stepped outer ring element 303 comprises a first diameter portion 305 and a second diameter portion 307, wherein the first diameter portion 305 has an inner diameter smaller than an inner diameter of second diameter portion 307. The stepped inner ring element

304 comprises a third diameter portion 308 and a fourth diameter portion 306, wherein the third diameter portion 308 has an outer diameter smaller than an outer diameter of the fourth diameter portion 306.

Further, the stepped outer ring element 303 comprises a first step portion 309 between the first diameter portion

305 and the second diameter portion 307, and the stepped inner ring element 303 comprises a second step portion 310 between the third diameter portion 308 and the fourth diameter portion 306

In the third embodiment, the first step portion 309 is substantially formed as a conical inner ring surface slightly inclined with respect to the rotational axis of the roll. Further, a corresponding end face of the stepped inner ring element 304 is formed as a conical outer end

face which forms the structural counterpart to the conical inner ring surface of the first step portion 309.

In contrast to the constitution of the second embodiment shown in Fig. 3, the second diameter portion 307 of the stepped outer ring element 303 corresponds to and faces the fourth diameter portion 306 of the stepped inner ring element 304. Thus, the inner diameter of the second diameter portion 307 is substantially the same as the outer diameter of the fourth diameter portion 306.

That is, both ring elements 303, 304 act as fitting elements 303, 304 which are fixedly connected to the respective tubes 301, 302 and comprise radial fitting sections 307, 306 and axial fitting sections 309, 310, which are different from each other.

Now, a manufacturing process of the roll is described in order to establish a fixed and stable connection between the two tubes 301 and 302 according to the third embodiment of the present invention as shown in Fig. 4.

Firstly, the outer tube 301 is pushed over the entire axial length of the inner tube 302 in a way similar to the one described in the first and second embodiments of the present invention. When the respective stepped ring elements 304, 303 get in contact with each other at the respective portions thereof, the axial and radial alignment between the inner tube 302 and the outer tube 301 is established. That is, the second diameter portion 307 of the stepped outer ring element 303 and the fourth diameter portion 306 of the stepped inner ring element 304 abut against each other for radial alignment of the tubes 301, 302, and the first step portion 309 of the stepped outer ring element 303 abuts against the conical outer end face

of the stepped inner ring element 304 such that axial alignment for the tubes 301, 302 is provided.

Then, the outer tube 301 including the stepped outer ring element 303 is provided with the injection aperture (hole) 313 by drilling, which extends in the radial direction of the tube 301 through the second diameter portion 307, and through which adhesive material 311 may be injected. Following this, an injection operation is executed which is similar to that of the first and second embodiments as described above. Of course, the injection aperture 313 may be formed before the tubes 301, 302 are assembled.

Thus, an adhesive joint between the ring elements 303 and 304 is formed by injecting the adhesive material 311 through the injection aperture 313 into a cavity which is defined by the second diameter portion 307, the second step portion 310, the fourth diameter portion 308 and the first step portion 309. That is, the adhesive joint is formed in the cavity only, this cavity not being responsible for the radial and axial alignment of the tubes 301 and 302.

After the hardening of the adhesive material 311 located between the outer and inner tubes 301 and 302, a fixed and stable connection (adhesive joint) for high rotational speed operations of the roll is established similarly as in the case of the connections of the above-mentioned embodiments shown in Figs. 2 and 3.

Figs. 5 and 6 are enlarged sectional views of a portion X in Fig. 1 showing a fourth embodiment of the present invention. The fourth embodiment shown in Figs. 5 and 6 essentially corresponds to the third embodiment shown in Fig. 4. In Figs. 5 and 6, similar parts are provided with the same reference numbers as shown in Fig. 4, increased by

the value 100. Moreover, the description of similar parts is therefore omitted. That is, only the structural differences of the constitution of sleeves 403 and 404 with respect to the third embodiment are described.

Fig. 5 showing the roll during assembly, and Fig. 6 showing the roll when assembled or fitted, depict the fourth embodiment of the present invention. In this embodiment, the fixed and stable fitting connection is not established by means of an adhesive joint but by means of a form fit connection as described below. Nevertheless, additional adhesive injection may be provided to further improve the stability of the connection.

The structural constitution of the sleeves 403 and 404 is generally the same as in Fig. 4.

A stepped outer ring element 403 comprises a positive form fit connection element 415 integrally arranged at a second diameter portion 407. The positive form fit connection element 415 is formed as a ring-shaped lip 415 extending radially towards a third diameter portion 408 of a stepped inner ring element 404.

The stepped inner ring element 404 comprises a negative form fit connection element or groove 416 integrally arranged at the third diameter portion 408. The negative form fit connection element 416 is formed as a ring-shaped groove 416 in the third diameter portion 408 and constitutes the structural counterpart to the ring-shaped lip 416.

Now, a manufacturing process of the roll is described in order to establish a fixed and stable connection between the two tubes 401 and 402 according to the fourth

embodiment of the present invention as shown in Figs. 5 and 6.

Firstly, the outer tube 401 is pushed over the entire axial length of the inner tube 402 and both are getting in axial and radial alignment to each other similarly to those alignments described in the third embodiment of the present invention .

In particular, when the outer tube 401 is pushed over the inner tube 402 and the ring-shaped lip 415 gets in contact with the third diameter portion 408 (see Fig. 5), a corresponding load is applied to the ring-shaped lip 415 which elastically deforms the ring-shaped lip 415 radially outwards and deflects it in the opposite direction of pushing the outer tube 401 (i.e. a tip of the ring-shaped lip 415 is deflected towards the right side in Fig. 5) .

Then, when a first step portion 409 of the stepped outer ring element 403 abuts against a conical end face of the stepped ring element 404, the ring-shaped lip 415 snaps into the negative form fit connection element 416 in order to establish a tight and fixed form fit connection between the respective ring elements 403 and 404 (and thus between the respective tubes 401 and 402) .

Therefore, the outer and inner tubes 401, 402 are axially and radially aligned to each other, and also a fixed and stable connection (form fit connection) between them is established in order to achieve high rotational speed operations of the roll without loosening of the fixed and stable connection.

The above embodiments of the present invention are intended to merely describe the present invention in an exemplary

manner and not to limit the present invention. The above embodiments may be modified as follows:

As mentioned above, in some of the above embodiments, it is preferred that the adhesive material for forming the adhesive joint between the respective fitting portions or elements (sleeves or ring-shaped elements) consists of resin material, preferably polymer material. Furthermore, it is also possible that the resin material substantially consists of incompressible resin materials, for example. Such materials exhibit small relaxation phenomenons during operations of the roll, so that the roll has good performance characteristics throughout its durability.

In addition, it is also advantageous that the used resin material has anti-vibration properties so that it can absorb deformation energy during operations of the roll.

In the above embodiments, it is preferred that the sleeves or ring-shaped elements are separate elements which are fixedly connected, preferably glued to the respective tubes. Alternatively, it is also possible to achieve fixing of the sleeves or ring-shaped elements to the tubes by means of shrink-fitting, welding, and the like. Furthermore, it is also possible that the respective sleeves and ring-shaped elements are integrally formed with the respective tubes. In this case, as the tubes generally consist wholly or partly of steel, aluminium, glass fibre- reinforced material, carbon fibre-reinforced material or other composite materials, the sleeves and ring-shaped elements are made of the respective material of the tubes, and thus having the same material properties.

Especially, in case the tubes are made of fibre reinforced plastic material, the sleeves and ring-shaped elements may

also comprise a plastic, steel or aluminium insert that is fitted on the tube surface during the tube manufacturing process by filament winding and is fixed to the tube by a layer or layers of wound fibre filaments, thus providing an integral structure. Especially, the ring-shaped element of the inner tube in its simplest form may be made even without the insert, i.e. by winding several extra layers of fibre locally on the tube until a desired thickness and shape is achieved.

In case the tubes are wholly or partly made of aluminium, glass fibre-reinforced material, carbon fibre-reinforced material or other composite materials, a light-weight and rigid roll is achievable.

Preferably, fibre-reinforced materials are applied to the tubes, for example glass fibre or carbon fibre-reinforced plastics. In particular, fibre-reinforced tubes exhibit a comparatively small inertia mass compared to tubes made of iron-based materials. Thus, the number of revolutions of such tubes can be adapted very fast to the respective conditions of the application requirements for rolls in paper machines.

Moreover, in the above embodiments, the stable and fixed connection is established by either an adhesive joint or a form fit. However, the present invention is not limited thereto. It is further possible to form the respective diameter portions of the sleeves or ring-shaped elements such that, additionally to the above-mentioned axial and radial alignment, a press fit connection between them is achieved.

That is, the stable and fixed connection is established by one or more press-fit surfaces of the sleeves or ring-

shaped elements. These press-fit surfaces have press-fit tolerances, such that said surfaces are press-fitted with each other by force fitting, shrinking, and the like. Thus, the stable and fixed connection is achieved by radial press forces acting between the respective press-fit surfaces.

Especially, in case of low rotational speeds of the roll, such a press fit connection between the sleeves or ring- shaped elements is sufficient in order to ensure a sufficiently strong joint between the inner shell surface of the outer tube and the outer shell surface of the inner tube to resist vibrations caused in different operations of the assembled roll.

Furthermore, the first, second and third embodiments having the outer tube including the outer sleeve (ring-shaped element) may be further provided with an additional aperture (not shown) for sucking off injected surplus adhesive material, which is preferably arranged on the outer shell surface of the outer tube opposite to the aperture for injecting, and extends in the radial direction of the outer tube. The surplus adhesive material may be sucked off by suction means (not shown) through the suction aperture .

Additionally, although only one injection aperture is provided for injecting resin material, it is also possible to provide two or more of such injection apertures. Thus, a better and faster distribution of the resin material at bonding surfaces of the sleeves may be established. The same may be applied for the constitution of the apertures for sucking off injected surplus adhesive material.

As described above, the injection aperture is drilled into the outer shell surface of the outer tube after the outer

tube and the inner tube form a pre-mounted unit, and are axially and radially aligned to each other. Alternatively, it is possible to pre-drill the respective aperture in the outer tube and the respective sleeve or ring-shaped element before the outer tube is pushed over the inner tube. In this case, a drilling step is not required anymore when the tubes are axially and radially aligned to each other.

Moreover, in the second and third embodiments, the first step portion of the stepped outer ring element is substantially formed as a conical inner ring surface in order to correspond to the associated conical end face of the stepped inner ring element. It is also possible to get conical surfaces and perpendicular circumferential edges of the respective ring elements in abutment such that the axial alignment of the tubes is achieved with the aid of pushing the different structural surfaces of the respective ring elements to each other in order to form a press fit between them, which is very tight and stably formed.

Furthermore, the adhesive material may be injected into respective adhesive pockets which are formed in the radial direction of the respective diameter portions for establishing an adhesive joint between the sleeves (ring elements) such that the adhesive material does not completely fill the respective contacting portions of the sleeves along their entire circumferential direction.

The preceding description of the present invention is merely exemplary, and is not intended to limit its scope in any way. Various details of the present invention may vary within the scope of the invention defined in the claims and may differ from the exemplary details described above in accordance with the knowledge of a person skilled in the art .