WO2010004521A1

WO2010004521A1 - Apparatus, and method thereof, for processing a web material

Info

Publication number: WO2010004521A1
Application number: PCT/IB2009/052993
Authority: WO
Inventors: Guglielmo Biagiotti
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-07-10
Filing date: 2009-07-09
Publication date: 2010-01-14
Anticipated expiration: 2011-01-10
Also published as: ITPI20080057A1; IT1390602B1

Abstract

A rewinding machine for creating logs (R) of web material (N) wound around a tubular core (A) comprises web feeding means for feeding the web material to a first winder roller (12) which together with a second winder roller (20) defines a winding cradle (21), core insertion means (40) for placing a tubular core in said winding cradle (21), and web interruption means (70) for severing the web material when a log is completed. The tubular core is introduced in a region (50) upstream, with respect to the web advance direction, a runner (60) made between the first winder roller (12) and the second winder roller (20) and in such region takes place the severing of the web, thanks to the web interruption means (70) that also support the cores in said region (50) keeping them in contact with the first winder roller (12). The rewinding machine of the invention has high reliability, has an optimized structure of the log change assembly and comprises adjusting means that make it suitable to process a wide range of logs and tubular cores sizes.

Description

Description Title of Invention: APPARATUS, AND METHOD THEREOF, FOR

PROCESSING A WEB MATERIAL

Field of the Invention

[1] The present invention concerns an apparatus for rewinding logs, around a tubular core, of a web material.

[2] In particular, the present invention concerns an apparatus for creating logs of toilet paper, kitchen rolls, industrial paper or other kinds of rolls of any size, comprising means for feeding the web material to a first winder roller which together with a second winder roller defines a runner through which the web material and the tubular core thereof pass to get to a winding cradle formed by said two winder rollers where the log grows, means for introducing the tubular core that are placed upstream the runner and means for interrupting the web material when a log is completed that are placed between the core introducing means and the runner. Description of the Prior Art

[3] In the paper industry are used machines, called rewinders, that create, from big logs of paper based material, toilet paper rolls, kitchen rolls, bath rolls of industrial type or other kind of rolls or logs of different material and even of big size.

[4] While having a similar working way this machines are structurally very different each other as a function of the kind and size of rolls or logs to realize.

[5] Small or medium sized rolls, specifically in the tissue sector, are obtained by machines whose main features have to be high reliability and productivity, as high that the web material is fed, in continuous, at a speed up to 1000 metres/minute.

[6] At that speed rates have to be assured high reliability and precision in particularly troublesome phases such as the log change process when a log is just completed and a new log starts winding around its tubular core.

[7] This kind of machines are disclosed in US patent documents n.4,828,195, n.4,723,724, n.5,979,818 and in the international application n.WO9534498.

[8] Specifically, in US5,979,818 is disclosed a rewinding machine, and method thereof, for making toilet paper rolls in which a paper punching assembly is mounted upstream the log change assembly providing a first steady axis winder roller about which the paper is fed and a second steady axis winder roller that makes together with the first roller a runner for the passage of the paper and core thereof about which the paper rolls up, while a third movable axis winder roller keeps the log in a winding cradle between said first and said second roller guiding the log formation. Upstream the runner, with respect to the paper direction, are placed core insertion means, where the cores arrive thanks to feeding means and individualisation means, and, from the core insertion means to the runner a conduit is obtained, between the first winder roller and a curved member, said conduit being as high as the diameter of the tubular core and shaped like a circular sector where the core rolls towards the runner. Within said conduit the paper is cut by paper interrupting means made of a pad that, mounted on 360° rotating support, periodically cooperates with the surface of the first winder roller in order to create on the paper surface friction forces in opposite directions that cause the web to break apart along a perforated line.

[9] The above described machine is undoubtedly one of the best machine actually on the market as it has high reliability and allows high web speed rates and then high productivity.

[10] Nevertheless, the structure of the log change assembly, and specifically the presence of the curved member apt to create the conduit guiding the tubular core render very difficult processing tubular cores and logs having different size since said curved member has to be replaced and various other elements have to be adjusted in length and position.

[11] The machine described in the international application WO9534498 aims to overcome, at least partially, the above problems by providing a similar machine in which said curved member is elastically mounted and it is therefore able to change its configuration when cores of different sizes pass through it. Furthermore, in order to allow the use of cores of different sizes in a same machine it is possible to adjust the position of other elements such us the web feeding and introducing means and the position of the second winder roller.

[12] The above improvements give the machine a greater versatility but it is still felt the need to find solutions apt to simplify the structure of the machine and apt to render it even more reliable and versatile as regards the kind of logs it is able to make.

[13] Logs of bigger size, mainly big logs for industrial use, are in fact usually formed by using machines that are structurally very different from the above described ones. In such cases, in fact, logs are formed in machines generally called slitter-re winders in which, upstream the log change assembly is installed an assembly for longitudinally cutting the web material to obtain partial webs that are wound around series of aligned tubular cores contemporaneously introduced in the log change assembly by specific loading means.

[14] This last type of re winders are disclosed, for instance, in patent documents

EPl 108669, US2989262, US3727854, US4422588 and US6129304.

[15] Mainly due to the big logs size and their heavy weights, this type of machines operates in a different way in respect of the previously described rewinding machines as the web speed can be very high but the log change process takes place by tern- porarily stopping the feeding of the web material. Summary of the Invention

[16] Object of the present invention is to provide an apparatus, and method thereof, for winding logs, around a tubular core, of web material, comprising means for feeding the web material to a first winder roller which together with a second winder roller defines a runner through which the web material and the tubular core thereof pass to get to a winding cradle formed by said two winder rollers where the log grows, means for introducing the tubular core that are placed upstream the runner and means for interrupting the web material when a log is completed that are placed between the core insertion means and the runner, said apparatus having a very simple and optimized structure apt to increase reliability of the machine.

[17] Further object of the present invention is to propose an apparatus for creating logs of web material apt to realize logs of a wide range of sizes and weights with a wide range of tubular cores, by simply adjusting the position of few elements.

[18] Another object of the present invention is to propose a method for creating logs of web material around a tubular core suitable and effective both for the series production of logs of small diameter such as toilet paper logs and for the formation of big industrial rolls.

[19] The above objects are attained through a rewinding machine for the formation of logs of web material wound around a tubular core, said rewinding machine comprising web feeding means, a first winder roller, a second winder roller which defines together with the first winder roller a runner where said tubular core and said web material pass through, core insertion means for introducing said tubular core placed upstream said runner referred to the web material advance direction, web interrupting means for interrupting said web material between a wound log and a newly introduced tubular core by periodically cooperating with said web feeding means in a region comprised between said core insertion means and said runner, and wherein said first and said second winder roller define a log winding cradle during the log formation phase, characterized in that said web interrupting means keep said tubular core in contact with said web feeding means along at least a portion of said region, said web material laying between said web feeding means and said tubular core.

[20] According to a preferred embodiment said web feeding the web interrupting means swing around a hinge member and they are provided with elastic means apt to minimize the gap between the web interrupting means themselves and the first winder roller.

[21] Still advantageously the web interrupting means are provided with actuator means apt to bring them in contact with said first winder roller in order to interrupt the web material when a log has been wound, the pressure of said web interrupting means against said first winder roller being limited by said elastic means.

[22] Advantageously the web interrupting means are provided with web interrupting members comprising at least one blade cooperating with at least one counter-blade integral to the surface of the first winder roller.

[23] Upstream said core insertion means, core processing means are provided apt to let an end of the web material severed by said interrupting means adhere to the external surface of said tubular core, thus the formation of a new log begins.

[24] The core processing means comprise a roller for applying glue on the core surface and all the components of the machine apt to enter in contact with said tubular core, within a region comprised between an adhesive application station for applying glue on the surface of the tubular core and a zone where the web material starts covering the glue, provide among their core contact members transversal gaps preventing the glue from coming in contact with said core contact members.

[25] Advantageously the rewinding machine comprises core cut means placed upstream said core insertion means and apt to split each tubular core in a plurality of tubular cores whose axis are on a same straight line.

[26] In this last embodiment the core insertion means introduce in said region a plurality of tubular cores at the same time, as well as said core insertion means and said web interrupting means have a rack- like structure consisting of a plurality of core contact members spaced so that each tubular core is contemporaneously supported by at least two core contact members.

[27] The above objects are also attained through a method of formation of logs of web material wound on a tubular core by means of a first winder roller around which at least partially rolls said web material and wherein the first winder roller forms, together with a second winder roller a log winding cradle, said method comprising phases of: feeding said tubular core towards a core insertion station, transferring said tubular core in said log winding cradle, interrupting said web material when a log has been wound, removing the formed log, and wherein the phase of transferring the tubular core in the log winding cradle comprises: a first phase of introducing said tubular core in a region upstream, referred to the web advance direction, a runner formed between said first winder roller and said second winder roller, a second phase of passing through said region in which said tubular core rolls between said first winder roller and said web interrupting means, said web material laying between said web feeding means and said tubular core, a third phase of said tubular core and said web material passing through said runner, between said first phase of introducing said tubular core and said third phase of passing through said runner taking place said phase of interrupting said web material.

[28] A rewinding machine according to the invention has the high productivity typical of the rewinding machines of the type disclosed in US5979818 and it also allows processing tubular cores of a wide range of diameters with the great advantage of very simple and reliable structure. [29] Further advantage of a rewinding machine according to the invention is the capability of forming big sized rolls just upon replacing or adjusting the position of few elements.

Brief Description of the Drawings [30] These and further advantages of the rewinding machine of the invention will be better understood by way of embodiment examples, that will now be described, with reference to the accompanying drawings, in which:

• figure 1 shows a schematic front view of an automatic rewinding machine with continuous web feeding according to the invention; D

• figures 2a to 2g show a detail of fig.1 in which are represented the components of a log change assembly in various steps of the log change process taking place when a log is completed and a new one starts winding; D

• figure 3 shows a top view of some components of the log change assembly; D

• figure 4 shows a detailed view of fig.1 pointing out the region where the web interrupting means cooperate with the first winder roller and, in a turned view is shown the shape of the interrupting members; D

• figure 5 shows a schematic front view of a different embodiment of a rewinding machine according to the invention, specifically a slitter-rewinder for creating big sized rolls; D

• figure 6 shows a detail of fig.5 in which are represented the components of a log change assembly; D

• figure 7 shows a view similar to the view of fig.3, in which is represented a different embodiment of the components shown in fig.3, the embodiment being particularly suitable for processing series of aligned tubular cores; D

• figure 8 shows a view similar to the view of fig.4 representing a different embodiment of the interrupting means. D

Detailed Description of Preferred Embodiments [31] In fig.1 are shown the main components of an automatic rewinding machine for winding around a tubular core a web of tissue paper to form toilet paper logs, kitchen paper logs or the like. [32] The web, N, is dragged through a series of traction rollers, 11, until it reaches a first winder roller, 12, where it partially turn around. [33] Along its path the web passes through a widener roller, 13, which is a tensor roller having curved axis and when the web passes over it is transversally stretched to its maximum width, then it passes through a punching assembly, 14, composed of a first roller, 15, which has helicoid disposed blades, 16, and of a second roller, 18, mounting a matching surface, 19, and the punching assembly makes in the web transversal perforated lines at the same longitudinal distance and perpendicular to the feeding direction.

[34] A second winder roller, 20, defines together with the first winder roller 12 a winding cradle, 21, where the log grows. In fact, the first winder roller 12 feeding the web N, the second winder roller 20 and a third roller, 22, rotate at a same peripheral speed so the log R is put into rotation around its axis. The roller 22 has a mobile axis and it moves away from the first and second winder roller as much as the log grows in diameter.

[35] The logs R grow around tubular cores, A, that are loaded in a feeder, 23, and then they reach a stop gate, 24, introducing them in special core keeping saddles, 25, transported by a chain conveyor, 26, moving through three tensor members, 27.

[36] The tubular cores, A, housed in the saddles 25 thereof descend along the upper branch of the chain conveyor 26 passing through glue applying means, 30, comprising a glue applying cylinder, 31, a tank, 32, containing the gluing fluid, and a counter cylinder, 33, mounted on pivotable supporting arms, 34, in order to fit various core diameters.

[37] Once passed through said glue applying means 30 the tubular cores A reach the core insertion means, 40, apt to let the core A enter a region, 50, comprised between the core insertion means 40 themselves and a runner, 60, defined by the gap between the two winder rollers 12 and 20 and designed to allow the passage of the core that so reaches the winding cradle.

[38] In the region 50 the tubular core A gets in contact with the web N dragged by the first winder roller 12 and, thanks to the web interrupting means, 70, the web is severed so that the downstream end of the web finishes winding around the log R and the upstream end of the web starts winding around the tubular core that has just entered the region 50.

[39] The main components of the log change assembly and the log change process are shown in figures 2a to 2g.

[40] In fig.2a a log R in the winding cradle 21 is almost completed. The motorized roller

12 drags the web N and together with the second winder roller 20 and the roller 22, motorized too, leads the log R to rotate about its axis thanks to the fact that the three rollers have a same peripheral speed, and this way the web winds around the core.

[41] A tubular core A is placed, ready to be inserted, at the core insertion means 40 comprising a support member, 41, an introducer, 42, pivoting around the support member 41, and a slide, 43, guiding the tubular core A in the first portion of the region 50 and maintaining it in contact with the first winder roller. [42] In the region 50 operate the web interrupting means 70 that comprise a shaped supporting arm, 71, pivoting around a hinge, 72, and comprising at its end interrupting members, 73, cooperating with the roller 12 to severe the web. The web interrupting means 70 further comprise elastic means, 74, that keep the interrupting members 73 close to the surface of the roller 12, said elastic means being, in the present embodiment, an air spring comprising an upper shell, 75, rigidly connected to the arm 71 and a lower shell, 76, pivoting around the hinge 72, the two shells defining a chamber,

77, containing a gas under pressure. The lower shell 76 is connected to actuator means,

78, moving it upwards and causing the interrupting members 73 to get in contact with the roller 12, the elastic means 74 acting between the actuator means 78 and the arm 71 in order to limit the pressure of the interrupting members against the roller 12.

[43] In fig.2b the log R is completed and the introducer 42 rotates picking the core A from the saddle 25 and taking it in contact with the web N that is turning around the roller 12.

[44] In fig.12c the tubular core A, rotated by the friction with the moving web N starts rolling on the support member 41 and then on the slide 43 and in this phase the actuator means 78 are operated to take the interrupting members in contact with the roller 12 so that the web is severed in correspondence to a perforated line previously created by the punching assembly 14. The upstream end of the web tends to fold and lay on the core A, and there, pressed by the roller against a film of glue previously applied on the core A, starts winding, while the downstream end of the web completes the log R that, at the same time, thanks to a reduction of the speed of the roller 20 begins to be unloaded from the winding cradle 21.

[45] In the following phase, shown in fig. 2d, the tubular core, going on in the region 50 finds the shaped arm 71 that, being elastically adaptable thanks to the elastic means 74, rotates around the hinge 72 pushed by the core A and at the same time supports the core itself keeping it in contact with the first winder roller 12.

[46] In fig.2e the tubular core A keeps rolling between the roller 12 and the arm 71 and reaches the end of the arm itself where the interrupting members are bound and, passed over the interrupting members it keeps rolling on a further slide, 51.

[47] It can be noticed that at the same time the log R has been unloaded and the roller 22 having movable axis has come back to a lower position getting closer to the winder rollers 12 and 20.

[48] In fig.2f is shown a phase in which the tubular core A, having a first portion of web

N wrapped around passes through the runner 60 keeping rolling between the winder rollers thanks to the fact that the second winder roller 20 rotates with a peripheral speed lower than the first winder roller 12, or, even, in a specific embodiment, it stops. Obviously the elastic means 74 have taken the interrupting members 73 back in a position close to the roller 12 just after the passage of the core.

[49] In fig.2g, the tubular core A has reached the winding cradle 21 and a new log is being formed, while a new core has been placed in correspondence to the core insertion means 40 ready to be loaded in the region 50 to start a new cycle.

[50] It could be easily understood that the rewinding machine and the rewinding method thereof above disclosed are very effective and reliable thanks to the improvement of the log change assembly. In addiction it is very simple to process tubular core of a wide range of sizes as it only needs to mount on sliding frames the sets of components involved in the log change and log formation processes.

[51] Certainly many changes could be made and many different arrangements could be provided to optimize the productivity, still remaining in the ambit of the above disclosed invention.

[52] In fig.3 is shown a top view of some components pointing out that when very long cores A are used, as usually occurs for producing toilet paper logs where the logs are transversally cut downstream the rewinding machine, it could be used a glue applying cylinder shaped so that it applies strips of glue C having a certain length. In order to avoid the glue to touch the machine components that come in contact with the core, such components are shaped to touch the core A in the portions of it where there are not glue stripes C. In particular, the core keeping saddles 25, the introducer, 42, the slide 43 and the shaped supporting arm 71 comprise portions apt to get in contact with the core having a vary small transversal size and placed in the transversal gaps between two subsequent glue stripes. Differently, the interrupting members 73 can be indifferently placed also in the transversal portion where there are the glue stripes since when the tubular core A reaches the interrupting members the web has started winding around the core so covering the glue that this way cannot stain the components coming in contact with the core.

[53] In fig.7, in a similar top view, are shown the same components shown in fig.3, according to a different embodiment of the invention particularly suitable to work with series of tubular cores Al, A2, ..., AN. In fact, it may happens, mainly when big logs have to be formed, that the tubular core A is transversally split before winding the log by cutting the core upstream the log change assembly in the rewinding machine or before entering the rewinding machine which, in this last case, is loaded with the core portions.

[54] Due to the little length of the single core portions Al, A2, ..., AN the distance between two subsequent support points in all the components that have to support the core without being touched by the glue must be reduced. A very effective solution is providing such components with a rack- like structure where two subsequent core support members are spaced enough to allow the passage of a glue stripe C applied by a glue applying cylinder 31' shaped as shown in figure, but still close enough one to the other so that at least two supporting members come in contact with one core portion Al, A2, ..., AN.

[55] In fig.7 may be noted the rack-like structure of the core keeping saddles, 25', of the introducer, 42', of the slide, 43', and of the shaped supporting arm, 71'.

[56] Obviously, the problem of letting the end of the web adhere to the tubular core A can be dealt with in a different way, either with solution known in the art or not. For instance, could be used nozzles apt to spray the gluing fluid on the surface of the core when they are to be inserted in the winding region, as well as cores provided with holes could be used together with means apt to create a vacuum pressure inside said cores so that the web is attracted towards the holes, or even means apt to give the cores an electrostatic charge, or other means could be used.

[57] In fig.4 is shown a detail of fig.l in which there are the interrupting members 73 comprising a series of pads, 79, with a rough surface apt to cerate friction with the surface of the web N. On the surface of the first winder roller 12 there are, transversally arranged in the gaps between the pads 79, further rough surfaces having annular shape and apt to create friction with the opposite surface of the web, said rough surfaces coming in turns with smooth surfaces facing the rough pads 79. Thanks to the action of the winder roller 12 together with the action of the pads 79 the web is severed. To make it happen along the perforated lines the actuator means 78 must be synchronized with the movement of the web N.

[58] In fig.8 is shown a different embodiment of the interrupting members 73 that may be preferred when the web is not provided with perforated lines.

[59] In this last embodiment the pads 79 are replaced by blades 79' acting together with corresponding counter-blades, 80, bound to the surface of the roller 12 by specific fastening means, 81. Also in this embodiment the web is severed by synchronizing the actuator means 78 with the rotation of the winder roller 12 to let the blades 79' and the counter-blades 80 work together.

[60] The interrupting means could move, instead of around the hinge 72, on a straight line, for instance in a direction perpendicular to the web feeding means. In particular, when said web feeding means coincide with the first winder roller the web interrupting means may move in a winder roller radial direction. Obviously, also in this case they could be provided with the elastic means and the actuator means.

[61] Further changes may concern the presence of core guiding components also apt to let them assume the correct transversal position and, at this aim, a chuck could provided inside the tubular core, inserted upstream the log change assembly.

[62] Strong structural modifications are usually needed in rewinding machines for big sized logs in which the web is stopped during the log change process. [63] On the contrary, as shown in fig.5 a rewinding machine according to the invention can be arranged in a very simple way for processing big sized logs.

[64] In fig.5 is shown a slitter-rewinder comprising traction rollers, 11", for feeding the web N, a widener roller, 13", and a longitudinal cutting assembly, 85, apt to longitudinally cut the web N slitting it in a series of adjacent tapes that then reach the first winder roller, 12".

[65] The second winder roller, 20", has its axis at the same height of the axis of the first winder roller 12", so that the log R grows with its axis vertically over the center of the winding cradle 21" and avoiding unbalancing that may be dangerous in view of the relevant weight of the formed logs. Still due to the weight of the logs the movable axis third roller 22" is mounted in a frame that also supports a centering assembly, 87, that keeps the axis of the tubular cores in the correct position.

[66] The tubular cores feeding assembly may comprise, along the feeder 23" a core cutting assembly, 88, that splits the core A in a series of adjacent tubular cores Al, A2, ..., AN around which the corresponding tapes of web slit by the longitudinal cutting assembly 85 wind.

[67] The glue applying member 31" is provided with protruding branches apt to apply glue in specific angular positions of the cores and dimensioned in function of the size of the core and of the other components of the log change assembly.

[68] In fig.6 is shown in detail the log change assembly comprising the core insertion means 40" in which the slide 43" is mounted with elastic means, 45, so that it is able to deal with a wide range of cores dimensions and it further comprises web interrupting means 70" pivotable around the hinge 72" and provided with elastic means 74" and actuator means 78".

[69] Still due to the relevant weight of the logs R during the log changing process the speed of the web is decreased by decreasing the speed of the rollers 12", 20" and 22". When the completed log must be unloaded and a new core must pass through the runner 60" the roller 20" is stopped to create a sufficient speed difference between the roller 12" and the roller 20".

[70] Certainly, many other changes and modifications may be carried out to the rewinding machine of the present invention, mainly with the scope of allowing it processing cores and logs of a wider range of dimensions, by replacing single components with other components having a similar function, still remaining within the ambit of the above disclosed invention and in the ambit of protection defined by the following claims.

Claims

[Claim 1] Rewinding machine for the formation of logs (R) of web material (N) wound on a tubular core (A), said rewinding machine comprising:

- web feeding means;

- a first winder roller (12);

- a second winder roller (20) which defines together with said first winder roller (12) a runner (60) where said tubular core (A) and said web material (N) pass through in an early phase of said formation of log (R);

-core insertion means (40) for introducing said tubular core (A) placed upstream said runner (60) referred to the web material advance direction (N);

- web interrupting means (70) for interrupting said web material (N) between a wound log (R) and a newly introduced tubular core (A) by periodically cooperating with said web feeding means in a region (50) comprised between said core insertion means (40) and said runner (60); and wherein said first (12) and said second winder roller (20) define a log winding cradle (21) during the log formation phase characterized in that said web interrupting means (70) keep said tubular core (A) in contact with said web feeding means along at least a portion of said region (50), said web material (N) laying between said web feeding means and said tubular core (A).

[Claim 2] Rewinding machine according to claim 1 characterized in that said web feeding means consist of said first winder roller (12).

[Claim 3] Rewinding machine according to claim 1 o 2 characterized in that said web interrupting means (70) swing around a hinge member (72).

[Claim 4] Rewinding machine according to one of the previous claims characterized in that said web interrupting means (70) are provided with elastic means (74).

[Claim 5] Rewinding machine according to one of the previous claims characterized in that said web interrupting means (70) are provided with actuator means (78) apt to bring them in contact with said first winder roller (12) in order to interrupt the web material (N) when a log (R) has been wound.

[Claim 6] Rewinding machine according to one of the previous claims characterized in that it comprises, upstream said core insertion means (40), core processing means (30) apt to let an end of the interrupted web material (N) adhere to the external surface of said tubular core (A), thus the formation of a new log (R) begins.

[Claim 7] Rewinding machine according to the previous claim characterized in that all the components of the machine apt to enter in contact with said tubular core (A), within a region comprised between an adhesive application station for applying glue (C) on the surface of the tubular core (A) and a zone where the web material starts covering the glue, provide among their core contact members transversal gaps preventing the glue from coming in contact with said core contact members.

[Claim 8] Rewinding machine according to one of the previous claims characterized in that it comprises core cut means (88) placed upstream said core insertion means (40) and apt to split each tubular core (A) in a plurality of tubular cores (Al, A2, ..., AN) whose axis are on a same straight line.

[Claim 9] Rewinding machine according to the previous claim characterized in that said core insertion means (40) introduce in said region (50) a plurality of tubular core (Al, A2, ..., AN) at the same time, said core insertion means (40) and said web interrupting means (70) having a rack-like structure consisting of a plurality of core contact members spaced so that each tubular core (Al, A2, ..., AN) is contemporaneously supported by at least two core contact members.

[Claim 10] Rewinding machine according to the previous claim characterized in that said tubular cores (Al, A2, ..., AN) are supported by chucks.

[Claim 11] Method of formation of logs (R) of web material (N) wound on a tubular core (A) by means of a winder roller (12) around which at least partially rolls said web material (N) and wherein the winder roller forms, together with a second winder roller (20) a log winding cradle (21), said method comprising phases of :

- feeding said tubular core towards a core insertion station;

- transferring said tubular core (A) in said log winding cradle (21) and start winding an edge portion of said web material (N) on said tubular core (A); - feeding said web material (N) towards said log winding cradle (21);

- interrupting said web material (N) when a log has been wound;

- removing the formed log R, characterized in that said phase of transferring said tubular core in said log winding cradle comprises:

- a first phase of introducing said tubular core (A) in a region (50) upstream, referred to the web advance direction, a runner (60) formed between said first winder roller (12) and said second winder roller (20);

- a second phase of passing through said region (50) in which said tubular core (A) rolls between said first winder roller (12) and said web interrupting means (70), said web material (N) laying between said web feeding means and said tubular core (A);

- a third phase of said tubular core (A) and said web material (N) passing through said runner (60); between said first phase of introducing said tubular core (A) and said third phase of passing through said runner taking place said phase of interrupting said web material (N). [Claim 12] Method according to the previous claim characterized in that during said phase of passing through said runner (60) the speed of said second winder roller (20) is set to zero, whilst the web material (N) keeps advancing.