Method and Apparatus for the Production of Coreless Paper Rolls

This application is based upon and claims priority to Italian Patent Application No. 102024000007270, filed on Apr. 3, 2024, the entire contents of which are incorporated herein by reference.

The invention concerns a method and an automatic apparatus for the production of coreless paper rolls and in particular an apparatus including a rewinding machine to rewind a tissue web unwound by a main reel to form smaller rolls on temporary spindles which at the end of the cycle are removed from the roll by an extraction device and finally sent by a transfer device to the rewinder machine for reuse of the same spindles for successive winding cycles.

At present, there are well-known machines called rewinders that perform the function of rewinding the paper web extracted from large diameter reels on smaller rolls or paper “logs” which can then be processed for subsequent cutting to size and packaging operations, while the rewinding machine automatically interrupts the continuity of the already wound web and starts a new winding.

Such a rewinder is described in the Italian patent application published as 102021000022814.

It is also known that some rewinding machines are designed to perform the rewinding of the web around cores or temporary cylindrical spindles which are then removed at the end of the winding in order to produce logs without a central core, also called “coreless”.

Among the known solutions, some include a variable geometry spindle that can shrink when the winding is completed in order to be removed from the log.

For example, a coreless winding apparatus is known from US2007152094 including a spindle with a pneumatically expandable flexible hose with a valve that allows the compressed air to be released and the spindle removed from the roll after the winding operation is completed.

From US2019161308 a rewinding machine is known including an extraction unit to produce coreless rolls, in which the paper web is wound on the spindle and at the end of the winding step a hydraulic actuator extracts the spindle from the roll.

A “coreless” winding system is also known for EP2711320B1, in which the deformability of the spindle is obtained by exploiting the axial and radial elastic elongation characteristics of the spindle subjected to traction during extraction from the formed log, which determines an elastic reduction in the diameter of the spindle, making it possible to extract it from the formed coil.

However, the well-known solutions have the disadvantage of relative complexity in the case of expandable spindles and excessive stress on the spindle in the case of deformable elastic spindles, which expose the spindle to the risk of breakage or damage and severely limit the possibility of reusing the spindles in subsequent work cycles.

These aims have been achieved by creating an apparatus and a method according to one or more of the annexed claims in which a step of first winding of the web on the spindle is carried out with a controlled initial tension lower than the winding tension at steady state that is carried out until the formation of the log, in such a way that the friction between the web and the external surface of the spindle is less than a predetermined value and consequently the corresponding axial force required to pull the spindle out of the inside of the roll.

A first advantage is that the temporary spindle can be easily removed without exerting traction that is harmful to it.

A further advantage is that temporary spindles can be used, consisting of simple rigid plastic tubes that can be reused several times.

With reference to the attached drawings, a preferred example of embodiment of an apparatus and a method according to the invention for the production of “coreless” paper rolls, or logs, is now described.

In the example shown in the figures, and in particular in, the apparatus includes a rewinding machine M for winding around a spindleof a webunwound by means of drive rollersfrom a main reelplaced upstream of the rewinder M, until the formation of a rollperformed by means of a winding unit, and subsequent execution of a subsequent cycle of interruption of the web coming from the main reel and new winding.

Downstream of the rewinder M in the direction of exit of the roll there is an extraction device E configured to receive from the rewinding machine the wound rollsand to extract therefrom spindleto obtain rolls without internal core. Further, downstream of the extractor E in the exit direction of the extracted spindles there is a transfer device T configured to receive from the extractor device E the spindlesand to transfer them cyclically to the rewinder machine M for the execution of a new winding.

According to the invention, the winding of the webaround the spindlesis carried out with a first winding phase, including one or more turns of the web on the central spindle, with a first winding tension that is less than the winding tension at the steady state of the successive revolutions performed until the completion of rollof the desired size, which tension is controlled in such a way that the friction between the web and the external surface of the spindle is less than what would be induced by the winding tension at steady state and, consequently, the axial force necessary for the extractor to extract the spindle from inside the coil can also be reduced.

Advantageously, with this solution, the spindle that is extracted, even if it has low mechanical characteristics of tensile strength and yield strength, maintains a substantially rigid behavior without undergoing significant deformation or elongation and can consequently be reused several times in the production cycle while maintaining the required functionality.

In different examples of actuation, it will therefore be possible to adjust the first winding tension also in relation to the mechanical characteristics of the spindle in order to ensure its rigid behavior during extraction. In addition, the first winding tension can be controlled in different ways, also depending on the type of rewinding machine used.

For example, it will be possible to adjust the relative speed of rotation of the web winding rollers around the spindle compared to the speed of feeding the web that is carried out by the reel through the drive rollers.

shows a particularly advantageous example of the construction of the rewinding machine M, in which the webis fed by the main reeland passes in succession first through a perforating unitfor the creation of transversal perforation lines of the web, then through a drive unitincluding an upper rollerand a lower rollerwhich control the advancement of the web, and finally a winding unitwhich provides for the creation of the logs or rollsby winding the web on a succession of spindles to be woundcoming from a feed.

In the example described, the winding unitincludes an upper winding rollerwound by the web, a lower winding roller, and a pressure roller or press, all in contact with the rollbeing formed and at least one of which is preferably motorized and controlled independently of the motorization of the drive unit.

In the example described, the press rolleris carried by an armrotating around an axisby means of an actuator(e.g. a linear hydraulic piston) in order to approach logon command and control its winding parameters, e.g. diameter and softness.

Finally, downstream of the winding unit there is a chutefor the expulsion of the wound logtowards the extractor device E.

During the winding phase, the paper film passes through the upper and lower rollers of the drive unitconsisting preferably of a smooth rollerand a rough roller, the rotation speed of which determines the speed of the feed of the webthrough the machine.

Downstream of the drive unit, the web passes through a spindle exchange channelwhich extends in the direction of the spindle transit between a sectionof first contact of the spindles with the paper web and a position P in which the growth of the rolltakes place by the action of the winding unit. In particular, the spindle comes into contact with the upper take-up rollerat a sectionof channeldownstream of the first contact sectionwith the web and stops in the growth position P also in contact with the lower rollerand the press.

In order to feed the spindles to the rewinding machine M, a spindle feeding rampis converging into channel, which ramp includes mobile shelvesdriven by a chainand driven by a pulleydriven by a motor. A gluing unitcan also be placed along rampfor the deposition along the spindles of one or more strips of glue intended to hold the initial flap of the plyin the subsequent first winding around the spindle.

In correspondence with the exchange channelthere are also means of handling the spindleswhich determine a rotation of the spindles in accordance with the direction of the weband with the same peripheral speed of the web at least when the spindles come into contact with the web.

Advantageously, the rotary motion imparted to the spindles allows a uniform winding of the webin the first turns, already upstream of the first contact with the upper winding roller.

Preferably, the means of handling can include a distribution of movable beltsin contact with the spindles in their direction of advancement towards the upper winding roller.

In the example described, there is also a contrast platebelow which the beltscan slide, arranged along the path of approach of the spindles to the take-up rollerand positioned adjacent to the lower horizontal tangent of the upper take-up roller.

Preferably, the beltsare underpinned by the tension desired by pulleyssupported by armsdriven by an actuator, for example a hydraulic actuator, and are moved in rotation by rollerbeing housed concealed in corresponding circumferential groovesso as to be overflow or slightly recessed with respect to the surface of the rolleritself ().

Advantageously, with this it is possible to control the rotation speed of the spindle to obtain a first winding tension lower than the winding tension at steady state in order to reduce the friction between the web and the outer surface of the spindle, and therefore the axial force required for the subsequent extraction of the spindle from the finished coil.

In the operation of the winding machine, when the log or rollbeing formed has reached the desired winding diameter or length, the exchange phase begins with the introduction of a new spindle from the transport device T during the winding phase.

The exchange phase is thus started and a pusherbegins to move by rotating around an axisand comes into contact with the stationary spindlewhich may have already passed through the gluing unitwhere it has received the glue necessary to take the paper film and start the new winding.

Before the core comes into contact with the winding rollers, the first winding of the web on the new core is preferably carried out pneumatically by sending a blade of air emitted towards the web by a blowerplaced close to the upper winding rollerfor its entire width and which push the web onto the spindle entering the exchange channel.

Pusherthen takes delivery of the spindle from rampand brings it into the exchange channel.

With the solution described, when the spindlepushed by the pusherhas reached the first contact sectionwith the web at the entrance of the exchange channel, it also comes into contact with the moving beltswhich cause it to rotate in agreement and with the same peripheral speed of the web, causing the first winding of the paper film coming from the drive unit, which adheres to the gluing areas, if any, already created on coreby the gluing unit.

In this phase, an interruption of the continuity of the web is also foreseen, obtained by breaking the web, typically along a transverse perforation line created by the perforation group.

Preferably, the interruption of the continuity of the web is carried out immediately after the first gluing of the final flap of paper of an already wound roll on the new incoming spindle, such that while the final flap of the wrapped paper on the finished rollis recalled and completes the previous winding, the initial flap of the paper of the new winding is already wound on the rotating spindle.

In the example described, the interruption of the web is carried out by sending a blow of pressurized air which is emitted from nozzlewhen the incoming spindle is in the first contact sectionand blocks the web, so that the sending of air causes an overtension that breaks the paper web.

The web interruption phase can in any case be carried out according to principles and techniques other than the use of an air blade as described above, for example by mechanically inducing a state of tension in the web at the end of the winding phase, by means of a web braking or a positive differential of the speed of movement of the web between the winding unit and the drive unit that induces a state of tension in the paper web.

For example, with reference toand IC the interruption of the web can be carried out by temporarily contrasting with the web and with the lower plateof the blowerby a padplaced at the end of the pusherfor the entire width of the web and which can be advantageously provided with groovesin correspondence with the belts, so as to compress and block the webwithout interfering with the rotation of the straps themselves.

With reference to, a preferred embodiment of the extraction device E for extracting the spindlesfrom the formed coilscoming, for example, from a chutefor the exit of the coils from the rewinding machine M, is now described.

In the example described, rollis accommodated by a centering element consisting of a first fixed inclined surfaceand a movable inclined surfacebetween a lowered position () at the arrival of the roll and a raised position () in which the moving surfaceis raised by a kinematic mechanismdriven by an actuatorand the roll is centered as a result of the convergence of the surfaces,.

With reference now to, the extractor E also includes a pushersliding along a crossbarparallel to the axis of the coilcentered between surfaces,and extended at least for the length of the roll itself being processed between a free endand an engagement endarranged in correspondence with a gripping unit, which will be later described in more detail with reference to.

After the centering of the roll, the pusherwhich is initially placed beyond the free end() is moved towards the gripping unitby a motor, not shown, in order to push the roll and to move it axially up to the position inin which the spindleis engaged by the unit, after which the pushercan be lifted along a vertical guide() to get out of the overall dimensions of the rolland finally, it can move together with the guidealong the crossbar, for example by a chain or beltdriven by a motoruntil it is placed beyond the first endof the rollnear the gripping unit.

With reference to, a possible construction form of the gripping headand its engagement with the spindle is described in greater detail. In the engagement position of, the rollhas been moved from the pusher to the gripping unitin the direction indicated by the arrow.

In the case described, spindleis a hollow spindle and the gripper unitincludes a holding device consisting in the example illustrated of an expansion headpossibly also equipped with chamfers in its insertion front part.

As shown in the figures, the headcan be operated by an actuatorto protrude axially from a containment sleeveand allow spindleto move towards unituntil the expansion headpenetrates inside the spindle cavity () and then moves back inside the sleeve together with the portion of the spindle protruding axially from roll().