WO2007004925A1

WO2007004925A1 - Method and device for cutting a log of paper or the like

Info

Publication number: WO2007004925A1
Application number: PCT/SE2005/001069
Authority: WO
Inventors: Anders Andersson
Original assignee: Sca Hygiene Products Ab
Priority date: 2005-06-30
Filing date: 2005-06-30
Publication date: 2007-01-11

Abstract

The present invention relates to a method for cutting a log of paper or the like into rolls, comprising - providing a log of paper (1) having an essentially circular cross-section with an original radius (rcirk) extending to a centre axis (A) of said log, - at least temporarily deforming at least a portion (10) of said log, so as to obtain a cross-section having at least one radius being greater than the original radius (rcirk) - providing a cutting device (2) for cutting said log into rolls, - starting the cutting operation from a first contact position (P) between the log (1) and the cutting device (2), wherein - the first contact position (P) being positioned on the periphery of the deformed cross-section of the log (1) at a location where a first contact radius (r) extending to a centre axis (A) of said log (1) is greater than the original radius (rcirk). It further relates to a device for cutting a log of paper into rolls.

Description

METHOD AND DEVICE FOR CUTTING A LOG OF PAPER OR THE LIKE

Technical field

The invention relates to a method and a device for cutting a log of paper or the like into rolls.

Background of the invention

In the paper industry, relatively large logs of rolled products such as paper or the like are produced. The logs are cut into smaller rolls having convenient sizes for kitchen paper, toilet paper, away-from-home rolls etc. Numerous methods and apparatuses have been proposed for performing the cutting of a log of a rolled product, such as paper or the like, into smaller rolls.

A device for cutting a log of paper or the like into rolls generally comprises a cutting device for performing the cutting, and a holding device for retaining the log during cutting thereof.

Firstly, there exist various different arrangements of the cutting device. The actual cutting may be performed using e.g. a saw blade or a band saw. Saw blades may be arranged in various different configurations as regards their suspension and movement in relation to the log to be cut. A circular saw blade may be arranged in e.g. a linear reciprocal arrangement, reciprocal on a radius, an orbital arrangement or an elliptical arrangement. A band saw is normally arranged in linear reciprocal arrangement in relation to the log, or alternatively reciprocal on a radius. When using a band saw, it is possible to move the blade or the log so as to perform the cutting operation. When using a circular saw, the blade is normally movable and not the log.

Secondly, various arrangements for retaining the log during cutting thereof into rolls have been proposed.

EP 0 982 105 describes a cutting machine where the clamping device comprises two sections crossed by a rocking saw. The clamping device comprises a support base for the log and a top clamp element capable of pushing the log against the base from above. EP 0 526 412 describes a clamping. device comprising a pair of symmetrically curved elastically flexible strips, having end portions able to move according to the variation in diameters of different logs.

EP 0 603 139 describes an apparatus for holding a log during the cutting thereof including a plurality of clamping elements distributed in a circle around the log. The clamping elements can be moved so as to allow the log to axially move between cuts. Each clamping element pivots around an axis so as to cause clamping of the log.

With known methods and apparatuses for cutting a log of rolled material into rolls, it has been observed that the edges of resulting rolls are sometimes not accurate, i.e. they are not straight. Thus, if the rolled-up material is unwound from the roll, it will be found that its edges will not form a straight line, but instead exhibit a sinus-like variation, also referred to as a cut deflection. The cut deflection causes problems when the rolls are positioned in dispensers or when packaged. Sometimes, the rolls will simply not fit in the dispenser or the package. Also, even if it is possible to introduce the roll into the dispenser or package, when the roll is unwound, the irregular edges may cause friction against the dispenser walls which hinders smooth unwinding of the rolled material. Further, the curved edges are not esthetically pleasing, something which becomes particularly apparent when motives are embossed or printed on the rolled material.

An object of the invention is therefore to provide a method and a device enabling production of rolls having edges more accurately following a straight line than rolls produced by previous methods and devices.

Summary of the invention The above-mentioned object is achieved by a method for cutting a log of paper or the like into rolls, comprising

- providing a log of paper having an essentially circular cross-section about a centre axis with an original radius extending from said centre axis to the circumference of said log, - at least temporarily deforming at least a portion of said log extending along said centre axis, so as to obtain a deformed cross-section having at least one radius being greater than the original radius

- providing a cutting device for cutting said log into rolls, - starting a cutting phase of a cutting operation from a first contact position between the log and the cutting device,

- the first contact position being positioned on the periphery of the deformed cross-section of the log at a location where a first contact radius extending to said centre axis of said log is greater than the original radius.

It has been found that the undesired impairment of the edges of the rolls is caused by the cutting device pressing the material in the log towards the log centre during cutting. The pressure on the roll causes an indentation in the log to be formed at the site of cutting, which in turn causes the observed sinus-like shape of the edges of the material of the roll resulting from the cut.

In the proposed method, at least the portion of the log where the cutting operation takes place is deformed so as to obtain a greater radius to the centre axis of the log than the original radius of the essentially circular log. It is believed that the deformation causes tension in the log which enables it to better withstand the force of the cutting device urging the material of the log inwardly, whereby a clearer cut is obtained.

With the term "radius" as used herein is meant a radius extending from the periphery of the log to the centre axis of the log. For a log having a circular cross section, the radius will be constant about the centre axis. For log having a non- circular cross section, the radius will vary about the centre axis.

The larger the first contact radius to the centre axis of the log, the greater the curvature of the circumference of the log at the first contact position. A greater curvature results in a lesser portion of the cutting device encountering log material at the first contact position. Thus, the force from the saw blade is concentrated on a smaller area of material, which can contribute to the enhanced cutting effect achieved.

The portion of the log is preferably at least temporarily deformed so as to obtain an essentially non-circular cross-section.

The deformation should be sufficient so as to deform the log at least for a period of time sufficient to perform a cutting phase of the cutting operation. The deformation may be made no greater than that the rolls may reassume their original substantially circular cross-section after cutting. Alternatively, the rolls may be clamped or pressed back to a circular cross-section after cutting. If instead a non-circular cross-section of the rolls is desired, the clamping may be made to cause a deformation which remains after cutting of the rolls.

A person skilled in the art may find a suitable deformation by varying the shape to which the cross-section is deformed, the pressure necessary to perform the deformation, and the time during which the deformation pressure is applied. Various logs will necessitate various types of deformation, depending on e.g. the log diameter, density, and material, and of the presence and characteristics of a core in the log.

Normally, logs of paper or the like originally have a circular cross-section, which is why the method may advantageously include a deformation step as above. In an alternative embodiment, the method may however be used to cut a log which already has a non-circular cross-section prior to the cutting operation.

Thus, in the alternative embodiment, there is provided a method for cutting a log of paper or the like into rolls, comprising providing a log of paper having a centre axis, - at least a portion of said log extending along said centre axis having a non-circular cross-section, said portion being located where said log is to be cut, providing a cutting device for cutting said log into rolls,

- starting a cutting phase of a cutting operation from a first contact position between the log and the cutting device, the first contact position being positioned on the periphery of the non- circular cross-section of the log at a location where a first contact radius extending to a centre axis of said log is greater than a corresponding circular radius being determined by the circumference of said non-circular portion/(2π).

Thus, in the case of a log having a non-circular cross-section prior to the cutting operation, the first contact radius may be compared to a corresponding circular radius, which is obtained by calculating the circular radius corresponding to the circumference of the non-circular portion. Using a log with a non-circύlar cross-section may be particularly advantageous if non-circular rolls are desired. As described above, the rolls may however be clamped to a circular shape after cutting.

The non-circular cross-section of the log may be achieved by pre-forming or deforming the log prior to the cutting operation.

Regardless of whether the log is pre-deformed or deformed in connection with the cutting only, the non-circular cross-section of the portion of the log is preferably essentially elliptical. An elliptical shape is relatively easy to create starting from a circular log and has been found to give satisfactory results. However, other shapes are imaginable, such as essentially square, triangular or rectangular shapes. These shapes may suitably have rounded outer corners, as the deformation should preferably be adapted so as not to cause visible alteration or damage to the material in the rolls.

Advantageously, the first contact radius is greater than an average radius of said non-circular cross-section, and preferably, the first contact radius is a maximum radius of the non-circular cross-section.

Preferably, the relationship between the first contact radius extending from the periphery of the non-circular cross-section of the log to a centre axis of the log and the corresponding or original radius (rcirk) is advantageously > 1.01, and preferably > 1.05. Advantageously the relationship may be in the range 1.01 to 1.30, advantageously 1.05 to 1.30, preferably in the range 1.05 to 1.20, most preferably in the range 01.08 to 1.15.

The proposed method is equally suitable for coreless logs as for logs having a core. When the log is provided with an inner core, it is preferred that the portion of the log with a non-circular cross-section likewise has an inner core with a non- circular cross-section. For coreless rolls, it is preferred that the log is deformed to an extent such that the portion of the log having a non-circular cross-section has a non-circular outer periphery as well as a non-circular inner periphery.

The deforming may advantageously be performed using a clamping device, including at least two pressure-applying devices for deforming said log. Preferably, the pressure-applying devices may be arranged so as to apply a greater pressure in a direction other than the direction in which the cutting device will initially cut the log, than the pressure in a direction substantially parallel thereto. Thus, the forces retaining the log in a deformed condition will act so as to counteract the force from the cutting device, whereby any tendency of the log to bulge inwardly under the pressure of the cutting device is reduced.

In a preferred embodiment, the pressure-applying devices are arranged so as to apply a greater pressure in a direction essentially perpendicular to the direction in which the cutting device will initially cut the log, than in a direction substantially parallel thereto. This is in contrast to known devices, where clamping of the log during cutting is usually made in a direction parallel or adjacent to the direction of cutting.

The pressure-applying devices may comprise at least two cooperating blocks, forming a non-circular intermediate space for receiving the log. The blocks may preferably be movable in relation to each other in a direction different from the direction in which said cutting device will initially cut the log, most preferably in a direction substantially perpendicular thereto.

It is understood, that for clamping the log, only one or both of the blocks may be movable.

In another embodiment, the deforming may be made by at least two circumferentially arranged pressure-applying devices, being arranged to apply different pressures, so as to deform the portion of the log to a non-circular cross-section. Thus, in this embodiment, the deformation is caused by different parts of the circumference of the log being subjected to pressures of different sizes from various pressure-applying devices.

In yet another embodiment, the pressure-applying devices may be arranged in a non-circular configuration about the log, so as to deform the portion of the log to a non-circular cross-section.

It is naturally possible to combine the features above, such that the pressure- applying devices are arranged in a non-circular configuration and exert different pressures on the log. The pressure-applying devices may comprise spring-loaded levers. Alternatively, the pressure-applying devices may comprise pistons pressurised by air or hydraulics, or mechanical motor-driven clamping systems.

The feeding of the log in relation to the cutting device may be made in any suitable way as is known in the art. The log may be sequentially fed towards the cutting device, and/or the cutting device may be sequentially moved along the log in order to perform the cutting operations along the log so as to produce a number of individual rolls.

When an initially circular log is used, a new portion having a non-circular cross- section may be formed for each cutting operation.

In a second aspect of the invention, there is provided a device for cutting a log of paper or the like into rolls, said log having a centre axis and an essentially circular cross section with an original radius extending from said centre axis to the circumference of said log

- a cutting device for cutting said log into rolls,

- a clamping device for at least temporarily deforming at least a portion of said log extending along said centre axis of said log, so as to obtain a cross-section having at least one radius being greater than the original radius, wherein

- said cutting device and clamping device are arranged in relation to each other, such that a first contact position between the log and the cutting device is defined for the start of a cutting phase of the cutting operation, said first contact position being positioned on the periphery of the non-circular cross-section of the log at a location where a first contact radius extending to said centre axis is greater than said original radius (rcirk).

Preferably, the clamping device is arranged so as to deform the log to an essentially non-circular cross-section.

The clamping device should clamp the log with a force sufficient so as to effect deformation of the portion of log at least for a period of time being sufficient to cut the log into rolls. As mentioned above, the clamping device may be arranged so as to effect a deformation which does not permanently alter the cross-section, i.e. the cut rolls may assume their original circular cross-section after cutting. A person skilled in the art may adjust the clamping device to the logs to be cut e.g. by varying the shape to which the cross-section is deformed, the force necessary to perform the deformation, and the time during which a deformation force is applied. Various logs will necessitate various types of deformation, depending on e.g. the log diameter, density, material, the presence and characteristics of a core.

In a second variant of a device for cutting a log of paper or the like into rolls, there is provided a device for cutting a log of paper or the like into rolls, said log having a centre axis and at least a portion extending along said centre axis having an essentially non-circular cross section with a varying radius extending from said centre axis to the circumference of said log, the device comprising - a cutting device for cutting said log into rolls, a clamping device for clamping a log of paper having at least a portion with a non-circular cross-section where said log is to be cut, said clamping device being arranged to hold the log in relation to the cutting device, such that a first contact position between the log and the cutting device is defined for the start of a cutting phase of the cutting operation, said first contact position is positioned on the periphery of the non-circular cross-section of the log at a location where a first contact radius extending to the centre axis is greater than a corresponding circular radius being determined by the circumference of said non-circular portion/(2π),

Advantageously, the non-circular cross-section of the portion of the log is essentially elliptical. Accordingly, the clamping device may be arranged so as to deform a log to an elliptical cross-section. Alternatively, the clamping device is arranged to hold a log already having an elliptical cross section.

Although an elliptical cross-section is particularly preferred, various other shapes are of course possible, such a square or triangular as mentioned above.

As has already been explained in relation to the method, the first contact radius (r) is preferably greater than a average radius of said non-circular cross-section, and is most preferably a maximum radius of the non-circular cross-section. Thus, the device may advantageously be arranged such that the relation between the cutting device and the damping device enables cutting at the desired radiuses.

The relationship between the first contact radius and the original or corresponding circular radius may advantageously be as described above in relation to the method.

The clamping device may include at least two pressure-applying devices for deforming said log. A pressure-applying device is a device suitable for applying a pressure to the log. One of the devices may have a fixed surface, towards which the other device is movable for applying the pressure. Alternatively, both of the devices may be movable.

Preferably, the pressure-applying devices are arranged so as to apply a greater pressure in a direction other than the direction in which said cutting device will initially cut the log, than in a direction substantially parallel thereto.

Advantageously, the pressure-applying devices are arranged so as to apply a greater pressure in a direction essentially perpendicular to the direction in which the cutting device will initially cut the log, than in a direction substantially parallel thereto.

In one embodiment, the pressure-applying devices may comprise at least two cooperating blocks, forming a non-circular intermediate space for receiving the log.

The blocks may be movable in relation to each other in a direction different from the direction in which said cutting device will initially cut the log, preferably in a direction substantially perpendicular thereto.

Further, the pressure-applying devices may be circumferentially arranged about the log, and adapted to apply different pressures, so as to deform the portion of the log to a non-circular cross-section.

Alternatively, the pressure-applying devices may be arranged in a non-circular configuration about the log, so as to deform the portion of the log to a non- circular cross-section. Other features as described above in relation to the method are equally applicable to the device according to the invention.

Brief description of the accompanying drawings Various features and advantages of the invention will be described in the following non-limiting description of preferred embodiments of the invention with reference to the accompanying drawings, wherein

Fig. 1 depicts a log of paper to illustrate the problem of prior art method and devices.

Fig. 2 illustrates schematically a piece of material being wound from a roll being cut from a log of paper as illustrated in Fig. 1

Fig. 3 illustrates schematically the cross-section of a first embodiment of a device according to the invention. Fig. 4 is a side view of the embodiment of a device illustrated in Fig. 3

Fig. 5 is a cross-sectional view of the clamping device of the embodiment of Fig.

3, depicted without the log of paper.

Fig. 6 illustrates a second embodiment of a clamping device in accordance with the invention. Fig. 7 illustrates a third embodiment of a clamping device in accordance with the invention.

Fig. 8 illustrates the deformation of the cross-section of a log of paper.

Detailed description of preferred embodiments of the invention Figs 1 and 2 are provided so as to illustrate the problem with non-straight edges of material which will sometimes arise when a log of paper or the like is cut into rolls using prior art techniques.

As illustrated in Fig. 1, and as described previously, an indentation 100 tends to be formed in a log of paper 1 during cutting thereof into rolls, The indentation is formed during the cutting, presumably by the pressure from the cutting device.

The indentation causes an irregular form of the material in the log during cutting, with the outcome that the edges of the material in the resulting roll will not be perfectly straight.

Fig. 2 illustrates the appearance of a piece of material being unwound from a roll of paper which has been cut from a log during the formation of an indentation.

The edges of the material do not follow a straight line, but will vary in an essentially sinusoidal shape. This variation is sometimes referred to as the roll deflection of the roll. Today, an accepted roll deflection is less than about 1.5% of the diameter of the roll.

As explained above, the present invention provides a method and a device for limiting the roll deflection by inhibiting the formation of indentations during cutting of the rolls from the log.

Fig. 3 is a schematic view of a first embodiment of a device for cutting a log 1 of paper or the like into rolls according to the invention.

The device comprises a cutting device 2 for cutting the log 1 into rolls. In this embodiment the cutting device 2 comprises a circular saw blade 12 that is arranged to be movable along a radius so as to cut the log 1. However, other arrangements of cutting devices such as e.g. circular saw blades being linearly movable or band saws are also suitable for use with the present invention.

The device further comprises a clamping device 3 for clamping the log 1 during cutting thereof. In the illustrated embodiment, the clamping device 3 is arranged so as to temporarily deform the cross-section 1 of a portion of the log 10 into a non-circular cross section. In this case, the non-circular cross-section is elliptical.

The elliptical shape is preferred, since it is relatively easy to deform the cross- section of the log 1 to that shape. Further, the log may easily assume its initial circular cross-section when released from the clamping device if deformed to an elliptical shape. However, other cross-sections such as those mentioned above are also suitable with the proposed method and device.

The log 1 has initially a substantially circular cross-section, as illustrated by the dashed line in Fig. 8. As may be seen in Fig. 8, the log 1 is deformed to an extent such that the core 6 is also deformed to a non-circular cross-section. When the log 1 is coreless, the log may be deformed such that its inner periphery is also deformed. The inner periphery of a coreless log is often somewhat irregular. Nevertheless, the inner periphery may usually generally be described as e.g. circular or oval.

The cutting device 2 and the clamping device 3 are arranged in relation to each other such that a first contact position P between the log and the cutting device is defined for the start of a cutting operation. The first contact position P is positioned on the periphery of the non-circular cross-section of the log 1 at a location where a first contact radius r extending to a centre axis A of the log 1 is greater than the original radius rcirk of the log.

In the illustrated embodiment, the first contact position P is positioned at a location where the first contact radius r is greater than an average radius of the deformed cross-section. However, in a most preferred embodiment, the first contact position is positioned at a location where the first contact radius r is the maximum radius rmax of the deformed cross-section. Such a device may easily be accomplished by arranging the saw blade in a corresponding relation to the clamping device.

In the illustrated embodiment, the clamping device 3 includes two pressure- applying devices 5 for clamping and deforming the log 1. In this case, the pressure-applying devices consist of two cooperating blocks 5 being shaped so as to, when brought into a clamping position, form a non-circular intermediate space 4 for receiving the log (see Fig. 5). In this case, the non-circular intermediate space 4 will thus have the same circumference as the originally circular log, but will form an ellipsoid instead of a circle so as to perform the deformation.

Since the log is to be cut from a first contact position P being positioned at a relatively large radius of the compressed cross-section, the maximum pressure applied to the roll for deformation will be applied from a direction other than the direction of cutting. In the illustrated embodiment, the pressure-applying devices 5, i. e. the two cooperating blocks 5, are movable in relation to each other in a generally horizontal direction. Also the maximum pressure applied will be applied in the horizontal direction, where the log will be submitted to the maximum extent of compression throughout its circumference. The cutting device 2 is arranged to cut the log 1 in a direction different than the horisontal plane, in this case in a direction forming an angle of approximately 45 degrees with the horisontal plane.

It is believed to be advantageous if the maximum pressure is applied from a direction being substantially perpendicular to the cutting direction, and it is preferred that the majority of the pressure is applied in a direction forming at least 45 degrees with the cutting direction. Fig. 4 is a schematic illustration of the device in Fig. 3, as seen in a side view. Here, it is seen how the clamping device 3 comprises two sets of pressure- applying devices 5, so as to deform a portion 10 of the log 1 where a cutting operation is to take place. The cutting device 2 is arranged in relation to the clamping device 3 so as to cut the log 1 in a gap formed between the two sets of pressure-applying devices 5. Thus, the portion 10 of the log 1 is accurately clamped and deformed throughout the cutting process. It is understood that, for each cutting operation, a new portion 10 of the log 1 is clamped so as to create a deformed cross-section at the site of each cutting operation.

For cutting the log 1 into rolls, the cutting device and the log 1 are movable in relation to each other. The log 1 may be sequentially fed in relation to the cutting device 2 and clamping device 3 so as to perform cutting operations over its length. Alternatively, the cutting device 2 and clamping device 3 may be movable along the length of the log 1.

Fig. 6 illustrates a second embodiment of a clamping device 3 being suitable for use with the invention. In this device, pressure-applying devices 5 are arranged circumferentially around the log 1. The pressure-applying devices 5 comprise pistons 13 extending from a base surface 14. In this case, a plurality of pressure-applying devices 5 is arranged to deform the roll. The pressure- applying devices 5 may be retracted towards the base surface 14 so as to allow insertion of the essentially circular log in the clamping device 3. For deformation of the log, some pistons 13 are extended a further distance from the base surface 14 than other pistons 13_rsuch that a non-circular circumference is formed between the ends of the extended pistons 13. Thus, the pistons 13 being the most extended will apply a greater pressure on the log 1 than the pistons being the least extended.

As described previously, the cutting of the log 1 should preferably take place in a direction other than the direction in which greatest pressure is applied.

Fig. 7 illustrates a third embodiment of a clamping device 3 being suitable for use with the invention. In this device, a plurality of pressure-applying devices 5 is arranged to form an ellipsoid. The pressure-applying devices 5 in the illustrated embodiment comprises spring loaded levers 11, for applying a pressure onto the log 1. The illustrated embodiments have been described in relation to a log originally having a circular cross-section. It is also feasible to deform the cross-section of the log, partly or entirely, before it is fed to the cutting device. In this case, the clamping device need not apply a pressure so as to deform the log, but will advantageously be shaped so as to receive a deformed log and to maintain the deformation throughout the cutting process. For determination of the correct placement of the first contact position P in the case of a pre-deformed log, the first contact radius may be compared to the corresponding circular radius of the non-circular cross-section, where the corresponding circular radius may be determined as the circumference of the non-circular cross-section/2π.

With the method as proposed herein, a cut deflection preferably less than 4 mm, and most preferred less than 3 mm is obtainable on a roll having a diameter of 260 mm. Thus, a cut deflection within the desired range of less than 1.5% of the diameter may be obtained. With the method and/or device as proposed herein, acceptable cut deflections may be obtained for a large variety of rolls.

The amount of deformation is preferably, as indicated above > 1%, most preferred >5%, considering the extension of the first contact radius in relation to the original or corresponding circular radius. In the illustrated embodiments, the relationship between a maximum radius and the circular radius is about 20%. However, it is understood that if the log is cut from a first contact position being present elsewhere than on the maximum radius, the relationship between the first contact radius and the original radius will be somewhat less than the relationship between the maximum radius and the circular radius.

Advantageous total deformations for the log, i.e. the relationship between the maximum radius and the original or imaginary radius are suitably >1.05, and advantageously in the range 1.05 to 1.30, preferably in the range 1.05 to 1.20, most preferably in the range 01.08 to 1.15.

In the illustrated embodiments, the log is deformed by application of pressure on the outer periphery of the log. In a not illustrated embodiment, pressure could instead be applied from the centre of the log acting outwardly towards its periphery. In particular, the pressure may be symmetrical, so as to achieve a log having a circular cross-section with a radius being greater than the radius of a relaxed log. This embodiment might be suitable in particular for coreiess, high bulk rolls.

Numerous embodiments and alternatives may be envisaged by the person skilled in the art. The form and arrangement of the pressure-applying devices may be varied so as to provide the desired non-circular cross-sections. The pressure- applying devices may be adjustable so as to provide sufficient deformation of logs having different characteristics, such as e.g. different diameters or densities. Further, any suitable cutting device may be selected to perform the cutting.

Claims

1. Method for cutting a log of paper or the like into rolls, comprising

- providing a log of paper (1) having an essentially circular cross-section about a centre axis (A) with an original radius (rcirk) extending from said centre axis (A) the circumference of the log (1),

- at least temporarily deforming at least a portion (10) of said log extending along said centre axis (A), so as to obtain a cross-section having at least one radius being greater than the original radius (rcirk) - providing a cutting device (2) for cutting said log into rolls, characterised in

- starting a cutting phase of the cutting operation from a first contact position (P) between the log (1) and the cutting device (2),

- the first contact position (P) being positioned on the periphery of the deformed cross-section of the log (1) at a location where a first contact radius (r) extending to said centre axis (A) of said log (1) is greater than the original radius (rcirk).

2. Method for cutting a log of paper or the like into rolls, comprising - providing a log of paper (1) having a centre axis (A), at least a portion (10) of said log (1) extending along said centre axis (A) having a non-circular cross-section, said portion (10) being located where said log (1) is to be cut, providing a cutting device (2) for cutting said log into rolls, - starting a cutting phase of a cutting operation from a first contact position

(P) between the log (1) and the cutting device (2),

- the first contact position (P) being positioned on the periphery of the non- circular cross-section of the log (1) at a location where a first contact radius (r) extending to a centre axis (A) of said log (1) is greater than a corresponding circular radius (rcirk) being determined by the circumference of said non-circular portion/(2π).

3. Method according to claim 1, wherein the portion (10) of the log extending along the center axis (A) is deformed so as to obtain an essentially non-circular cross-section.

4. Method according to claim 2 or 3, wherein the non-circular cross-section of the portion (10) of the log (1) is essentially elliptical.

5. Method according to any one of the claims 2-4, wherein said first contact radius (r) is greater than an average radius of said non-circular cross-section.

6. Method according to claim 5, wherein said first contact radius (r) is a maximum radius (rmax) of the non-circular Cross-section.

7. Method according to any one of the preceding claims, wherein the relationship between the first contact radius extending from the periphery of the non-circular cross-section of the log to a centre axis of the log and the corresponding or original radius (rcirk) is in the range 1.05 to 1.30, preferably in the range 1.05 to 1.20, most preferred in the range 1.08 to 1.15.

8. Method according to any one of the preceding claims, wherein the portion (10) of the log having a non-circular cross-section has a non-circular outer periphery as well as a non-circular inner periphery.

9. Method according to claim 8, wherein the log is provided with an inner core (6), said inner core (6) having a non-circular cross section in the portion (10) with a non-circular cross-section.

10. Method according to any one of the claims 2-9, including clamping at least the portion (10) to be cut of an initially essentially circular log (1) so as to form the non-circular cross-section.

11. Method according to claim 10, wherein said deforming is performed using a clamping device, including at least two pressure-applying devices for deforming said log.

12. Method according to claim 11, wherein the pressure-applying devices apply a greater pressure in a direction other than the direction in which said cutting device will initially cut the log, than in a direction substantially parallel thereto.

13. Method according to claim 12, wherein the pressure-applying devices are apply a greater pressure in a direction essentially perpendicular to the direction in which the cutting device will initially cut the log, than in a direction substantially parallel thereto.

14. Method according to claim 10, whereiri the pressure-applying devices comprises at least two cooperating blocks (5), forming a non-circular intermediate space (4) for receiving the log.

15. Method according to any one of the claims 10 to 15, wherein said deforming is made by at least two circumferentially arranged pressure-applying devices (11), being arranged to apply different pressures, so as to deform the portion (10) of the log to a non-circular cross-section.

16. Method according to any one of the claims 10 to 14, wherein the pressure- applying devices (11) are arranged in a non-circular configuration about the log (1), so as to deform the portion (10) of the log (1) to a non-circular cross- section.

17. Method according to any one of the claims 10 to 16, wherein the pressure- applying devices (11) comprises spring loaded levers.

18. Device for cutting a log of paper or the like into rolls, said log having a centre axis (A) and an essentially circular cross section with an original radius (rcirk) extending from said centre axis (A) to the circumference of said log, the device comprising

- a cutting device (2) for cutting said log (1) into rolls,

- a clamping device (3) for at least temporarily deforming at least a portion (10) of said log extending along said centre axis (A) of the log (1), so as to obtain a cross-section having at least one radius being greater than the original radius (rcirk). characterised in

- said cutting device (2) and clamping device (3) being arranged in relation to each other, such that a first contact position (P) between the log and the cutting device is defined for the start of a cutting phase of the cutting operation, said first contact position being positioned on the periphery of the non-circular cross- section of the log (1) at a location where a first contact radius (r) extending to the centre axis (A) is greater than said original radius (rcirk).

19. Device for cutting a log of paper or the like into rolls, said log (1) having a centre axis (A) and at least a portion (10) extending along said centre axis (A) having an essentially non-circular cross section with a varying radius extending from said centre axis (A) to the circumference of said log, the device comprising comprising a cutting device (2) for cutting said log (1) into rolls, a clamping device (3) for clamping a log (1) of paper having at least a portion (10) with a non-circular cross-section where said log is to be cut, said clamping device being arranged to hold the log in relation to the cutting device, such that a first contact position (P) between the log and the cutting device is defined for the start of a cutting phase of the cutting operation, said first contact position (P) is positioned on the periphery of the non-circular cross-section of the log at a location where a first contact radius (r) extending to the centre axis (A) is greater than a corresponding circular radius (rcirk) being determined by the circumference of said non- circular portion/(2π).

20. Device according to claim 19, wherein the portion of the log is deformed so as to obtain an essentially non-circular cross-section.

21. Device according to claim 18 or 20, wherein the non-circular cross-section of the portion (10) of the log (1) is essentially elliptical.

22. Device according to any one of the claims 18-21, wherein said first contact radius (r) is greater than a average radius of said non-circular cross-section.

23. Device according to any one of the claims 18-22, wherein said first contact radius (r) is a maximum radius (rmax) of the non-circular cross-section.

24. Device according to any one of the claims 18-22, wherein wherein the relationship between the first contact radius extending from the periphery of the non-circular cross-section of the log to a centre axis of the log and the corresponding or original radius (rcirk) is in the range 1.05 to 1.30, preferably in the range 1.05 to 1.20, most preferred in the range 1.08 to 1.15.

25. Device according to any one of the claims 18-24, wherein the clamping device (3) includes at least two pressure-applying devices (5) for deforming said log (l).

26. Device according to claim 25, wherein the pressure-applying devices (5) are arranged so as to apply a greater pressure in a direction other than the direction in which said cutting device will initially cut the log, than in a direction substantially parallel thereto.

27. Device according to claim 26, wherein the pressure-applying devices (5) are arranged so as to apply a greater pressure in a direction essentially perpendicular to the direction in which the cutting device will initially cut the log, than in a direction substantially parallel thereto.

28. Device according to any one of the claims 18-27, wherein the pressure- applying devices comprises at least two cooperating blocks (5), forming a non- circular intermediate space (4) for receiving the log.

29. Device according to claim 28, wherein said blocks (5) are movable in relation to each other in a direction different from the direction from which said cutting device will initially cut the log.

30. Device according to any one of the claims 26-29, wherein the pressure- -, applying devices are circumferential Iy arranged about the log, and adapted to apply different pressures, so as to deform the portion (10) of the log to a non- circular cross-section.

31. Device according to any one of the claims 26-30, wherein the pressure- applying devices (11) are arranged in a non-circular configuration about the log (1), so as to deform the portion (10) of the log (1) to a non-circular cross- section.

32. Method according to any one of the claims 26-31 wherein the pressure- applying devices (11) comprises spring loaded levers.