Technical field

This invention relates to a machine for the production of rolls of paper material and the related winding process.

Background art

The so-called “rewinding machines”, designed for the production of rolls (or logs) of paper material, for example rolls of paper of the “tissue” type, such as rolls of kitchen paper, toilet paper, etc., unwind webs of paper from a reel of origin for winding them on rolls (also called “sticks” or “logs”) designed for subsequent processing for the production of rolls of paper for household use.

There are various types of rewinding machines on the market, mainly based on separating devices which, during the unwinding of the paper, with the winding of a new log finished, slow the web causing the breakage and allowing both the unloading of the wound log and the loading of a new core to be wound.

In general, rewinding machines comprise a unit for driving the web to be wound and, downstream in the direction of advance of the web, a motor- driven winding unit designed to wind the web of paper, fed by the pulling unit, about a tubular winding core, in such a way as to form a paper log, of desired dimensions. the winding units of known type comprise a primary roller and a secondary roller rotating in contact with the core being wound, and at least one pressure unit equipped with a pressure roller, the so-called presser, rotating in contact with the log being formed. The presser can move away from the primary and secondary rollers, for example by means of rotary arms.

A machine of this type is known from patent application EP3601122 in which is present: the drive unit, which feeds the web of paper; the log winding unit; the primary and secondary rollers which rotate in contact with the core being wound; two pressure units, each equipped with a rotating compression roller on the log being formed; a system for loading the cores to be wound which introduces, simultaneously with the expulsion of the roll formed, a new core; separating means to interrupt the continuity of the web of paper at the end of the winding cycle, which will then be re-wound in the new core introduced.

According to this embodiment, the pressure unit comprises two motor- driven pressure rollers, also called pressers, which are arranged to alternate in a position relative to the log, so as to rotate simultaneously in contact with the log being formed at least during a part of the winding step, both with a peripheral speed substantially equal to the winding speed of the web.

According to the rewinding machine described in the prior art, a core is inserted in the winding channel defined by the two rollers (primary and secondary). The core is in contact with these two rollers during its initial start-up step: after a certain diameter is reached, the first presser comes into contact with the growing roll resulting in the growth and, subsequently, a second presser also comes into pressure.

In the end part of the winding step, the log is growing with the two pressers simultaneously in contact, together with the primary roller.

At the end of the winding step, the interrupting means cause the separation of the web of paper whilst the two pressers continue to rotate always in contact with the log.

In this system, the interruption step is performed by means of a pneumatic dispensing device or, alternatively, by imposing an acceleration of the pressers: the increase in the peripheral speed of the web on the log at the point of contact with the pressers relative to the preset advancement speed of the log induces, in effect, a tension in the portion of web of paper upstream, and therefore a breakage and interruption of the continuity of the web, at the pre-cutting normally provided along the extension of the web.

Lastly, the roll formed is expelled and, at the same time, a new core is inserted to be wound in the winding channel.

This machine is very efficient, however it has certain problems and drawbacks.

At the start of the winding step, of the roll, it is controlled only by the two primary and secondary rollers. This determines an instability in the winding which may result, especially during this step, in the breakage of the web. This problem is overcome by modulating the speed of the secondary roller, which is therefore suitably varied, and controlling its opening relative to the primary roller (that is to say, by adjusting the distance between the two centres of rotation of the primary and secondary rollers).

In particular, in logs with very large final diameters there is a critical step in exchanging control between the pressure rollers.

In order to manage the winding, it is necessary to implement a particular control of the profile of the secondary roller, customising it relative to the product.

In other words, in order to optimise the effectiveness of this machine it is necessary to vary the parameters of speed of rotation and opening of the second roller on the basis of the specifications of the roll to be made, such as the diameter of the core and the final diameter of the completed roll, the length, the winding, the thickness of the paper, etc.

Aims and summary of the invention

The aim of the invention is to overcome the above-mentioned drawbacks of prior art types of machine for the production of rolls of paper material and the related winding process which allows a secure gripping by the presses, in such a way as to ensure the complete winding of the roll of paper with a more stable process.

In the context of the above-mentioned purpose, an aim of the invention is to improve the winding reliability and efficiency, especially during the initial step of winding the log, facilitating management of the control parameters. Yet another aim of the invention is to provide a machine for the production of rolls of paper material and the related winding process, with means which are easily available on the market and using materials of common use, in such a way that the device is economically competitive.

Brief description of the invention

This purpose, as well as these and other aims, which are described in more detail below, are achieved by a machine for the production of rolls of paper material and the related winding process, according to the invention comprising the technical features described in one or more of the appended claims. The dependent claims correspond to possible different embodiments of the invention.

In particular, according to a first aspect, this invention relates to a machine for the production of rolls of paper material which by the simultaneous control of three of the four rollers (two for winding and two for pressing) with which it is equipped, guarantees an extreme stability for the system, limiting and even eliminating dangerous vibrations, which could put at risk the integrity of the web of paper which winds around the cores (for forming the roll), as well as the instability generated in the first step of winding the roll.

Preferably, this contact action which is exerted simultaneously by at least three of the rollers with which the machine is equipped is always ensured between the initial position and the cutting of the web, that is to say, during the winding of the paper around the log.

In other words, the machine for the production of rolls of paper material according to the invention comprises at least a first and a second winding roller, both rotatably mounted, respectively, about a first and a second axis of rotation, and at least a first and a second pressure roller, both designed to rotate, respectively, about a third axis of rotation, positioned on a first movable arm, and a fourth axis of rotation, positioned on a second movable arm. The at least four rollers mentioned above define a channel for winding a web of paper which is intended to be wound around a core in continuous rotation, initially on its own but then together with the growing roll, pivoting on its own axis of rotation, for forming a roll. The winding rollers are positioned, relative to the pressure rollers, on opposite sides of said winding channel, respectively upstream and downstream of the winding channel, relative to the movement of the core in the channel during the winding process. The core is designed to be moved by the action of one or more of the winding and pressure rollers, between an initial winding position of the web of paper (6) and a final position. The two movable arms pivot, respectively, on a first and a second secondary axis of rotation, in such a way that their rotation moves the first and/or the second pressure roller towards or away from the first and/or the second winding roller. At least three of the above-mentioned rollers are designed to exercise a simultaneous control of the roll of paper wound around the core between the initial position of the channel, that is, when at least the centre line of the core has passed beyond the axis joining the centres of rotation relative to the winding rollers, or - even more preferably - when the profile of the outermost perimeter of the core is tangential to the joining line and its centre line has already passed beyond the axis, until the web of paper wound around the core is suitable for being cut.

A second feature of the invention relates to the “V” shape of the first movable arm due mainly to the fact that the Applicant has positioned the first axis of secondary rotation of the second arm in such a way as to move it in the half-plane determined by the joining line of the two centres of rotation of the winding rollers and opposite with respect to the winding channel, so as to allow the oscillation of the first pressure roller in such a way as to allow an improved control of the log in the initial step.

Another aspect of the invention relates to the winding process used to form rolls of paper by means of such a rewinding machine.

Brief description of the drawings

Further features and advantages of the invention are more apparent in the detailed description below, with reference to a preferred, non-limiting embodiment of the machine for the production of rolls of paper material and the related winding process, illustrated by way of example and without limiting the scope of the invention, with the aid of the accompanying drawings, in which:

Figures 1 to 10 schematically show the configurations of the winding rollers 11 and 21 and the pressure rollers 31 and 41 during the movement and the formation of the rolls being wound around the cores 5’ and 5” in the winding process in the machine 1 for the production of rolls of paper material;

Figures 11 -21 schematically show the configurations of the rollers 11 , 21 , 31 and 41 during the movement and the formation of the rolls being wound around the cores 105’ and 105” in the winding process in the machine 101 for the production of rolls of paper material; in particular, Figure 11 A shows a detail of Figure 11 ;

Figure 22 schematically shows the shape of the first arm 32, in a plan view;

Figures 23A and 23B schematically show, respectively, the upstream limit and the downstream limit of the winding channel 7.

Detailed description of the actuation of invention

The above-mentioned drawings show a preferred embodiment of a machine for the production of rolls of paper material and the relative winding process, according to the invention, which is denoted in its entirety by the numeral 1 or 101 which comprises at least four rollers: a first 11 and a second 21 winding roller rotatably mounted, respectively, about a first 10 and a second 20 axis of rotation; and a first 31 and a second 41 pressure roller, designed to rotate, respectively, about a third axis of rotation 30 positioned on a first movable arm 32, and a fourth axis of rotation 40 positioned on a second movable arm 42. The four rollers 11 , 21 , 31 and 41 define a winding channel 7 for a web of paper 6 around a core 5’, 5”, 105’ or 105”, rotating about a relative axis of rotation 50’, 50”, 150’ and 150”, for forming a roll. The two winding rollers 11 and 21 are positioned on opposite sides of said winding channel 7 relative to the two pressure rollers 31 and 41 , respectively upstream and downstream of the winding channel 7, relative to the unwinding of the winding process of the core 5’, 5”, 105’ and 105”.

Obviously, initially the core 5’, 5”, 105’ and 105” rotates about the axis 50’, 50”, 150’ and 150” on its own, but then together with the roll as it grows.

In this sense, therefore, the web 6 comes from a point upstream of the channel 7. The first 32 and the second 42 movable arm pivot, respectively, on a first 30 and a second 40 secondary axis of rotation, in such a way that the rotation of the first 32 and/or the second 42 movable arm moves the first 31 and/or the second 31 pressure roller from or towards the first 11 and/or the second 21 winding roller: obviously, if the first movable arm 32 rotates, it will allow the movement of the first pressure roller 31 towards or away from one of the winding rollers 11 or 21 , vice versa the rotation of the second movable arm 42 will cause the movement of the second pressure roller 41 towards or away one of the winding rollers 11 or 21 .

The roll which forms on the core 5’, 5”, 105’ and 105” is controlled by the action of one or more of the rollers 11 , 21 , 31 and 41 , between an initial position, corresponding to the winding zone of the log, and a final position, corresponding to the expulsion zone 9 of the roll formed.

In particular, the initial position occurs from the moment in which at least the centre line of the core 5’, 5”, 105’ or 105” has passed beyond the axis K joining the centres of rotation C1 and C2 relative to the rollers 11 and 21 , even more preferably when the profile of the outermost perimeter of the core 5’, 5”, 105’ or 105” is tangent to the joining line K (and its centre line has already passed beyond the theoretical line), as can be seen in Figure 23A.

The term winding channel 7 means that portion of the area delimited by the four rollers 11 , 21 , 31 and 41 which is defined, upstream relative to the movement of the logs by the joining line K, immediately after the channel 8 for introducing the core 5’, 5”, 105’ or 1 ’5” to be wound (upstream limit), and, downstream, by the line H joining the centres of rotation C2 and C4 relative to the rollers 21 and 41 (limit downstream, Figure 23B), immediately before the expulsion zone 9 of the formed roller.

A main feature of the machine according to the invention is due to the fact that, in the initial position, at least three between the first 11 and the second 21 winding roller and the first 31 and the second 41 pressure roller exercise a simultaneous control of the roll of paper which is wound around the core 5’, 5”, 105’ or 105” and the contact action of at least three of the rollers 11 , 21 , 31 and 41 is always guaranteed by the machine between this initial position and the cutting of the web 6.

Preferably, in the initial winding position, the core 5’, 5”, 105’ or 105” does not have layers of paper wound around its own axis of rotation 50’, 50”, 150’ or 150”, whilst in the final position the roll is completely wound.

Advantageously, in the initial position, the first winding roller 11 , the second winding roller 21 and the first pressure roller 31 simultaneously control the roll of paper which is wound around the core 5’, 5” or 105”, whilst with regard to the core 105’ this is controlled, again in the initial position, simultaneously by the second winding roller 21 , by the first pressure roller 31 and by the second pressure roller 41 .

This synergic action makes the machine extremely more stable during the outfeed of the finished roller, completely wound around the first 5’ and 105’ and the new core 5” and 105”, that is to say, when the old log leaves the winding zone.

Advantageously, in the final position, the second winding roller 21 and the second pressure roller 41 simultaneously exercise a control of the roll of paper which is wound around the core 5’, 5”, 105’ or 105” already formed, to accompany them to the expulsion, therefore allowing the log which has just faced the winding channel 7 to be “treated” by three rollers, in particular by the winding rollers 11 and 21 and the presser 31 .

In practice, the second winding roller 21 and the second pressure roller 41 simultaneously control the roll of paper which is wound around the first core 5’ or 105’ which is in the final position and, simultaneously, the first winding roller 11 , the second winding roller 21 and the first pressure roller 31 are in simultaneous control of the roll of paper which is wound around the second core 5” and 105” which is in the initial position.

In order to favour the introduction of the second core 5” or 105” whilst the first core 5’ or 105’ has already completed its winding and is ready to be expelled from the channel 7 as a formed roll, the first movable arm 32 is advantageously rotated about the first secondary axis of rotation 30, so as to allow the sliding of the first pressure roller 31 on the core 5” or 105” which forms along the winding channel 7. The gradual movement of the presser 31 , that is to say, the sort of sliding just described, prevents sudden movements to the system, giving an improved stability to the machine, considering the sudden movements which cause harmful vibrations due to the fragile condition of the web of paper 6 to be wound.

In this regard, the Applicant understood that by moving the first axis of rotation 30 of the arm 32 in such a way as to bring it into the half-plane determined by the joining line K of the two centres of rotation C1 and C2 of the rollers 11 and 21 and opposite with respect to the winding channel 7, it is possible to oscillate the first presser 31 in such a way as to allow an improved control of the log in the initial step.

With reference to Figure 1 , in order to implement that configuration, due to the dimensions of the primary roller 11 and of the second arm 42, the Applicant had to shape the arm 32 substantially like a “V”.

Advantageously, the “V” shape is formed in such a way that the angle Z defined by the contact of the axes of symmetry S31 and S30, respectively referred to the end portions of the arms 32A and 32B at the pressure roller 31 and the axis of rotation 30 (and passing through the axis 30 and the centre C3), is between 40° and 80°, inclusive, preferably between 45° and 70°, inclusive, more preferably between 50° and 65°, inclusive, even more preferably between 53° and 60°. For practical purposes, the arm 42 is also made in the usual way. The purpose of the latter is to provide good control of the log during the final winding step, that is to say, when it is accompanied to the expulsion zone 9.

The process for winding the paper around the logs, for the production of rolls of paper material, in the above-mentioned rewinding machine 1 or 101 , comprising the steps of:

- introducing a first core 5’ or 105’ inside the winding channel 7,

- winding the web of paper 6, coming from an introduction channel 8 upstream of the winding channel 7, around the first core 5’ or 105’ rotatable about its own axis of rotation 50’, 150’, to form a first roll and, simultaneously, move the first core 5’ or 105’ by means of the second winding roller 21 , the first pressure roller 31 and the second pressure roller 41 , until this first partially wound core 5’ or 105’ reaches a position downstream of the winding channel 7 and the first movable arm 32 is therefore allowed to enter the winding channel 7,

- cutting the web of paper 6 to complete the first roll,

- introducing a second core 5” or 105” inside the channel 7, winding it with the cut web 6, about the relative axis of rotation 50” or 150” to form a second roll and, simultaneously, moving the second core 5” or 105”, thanks to the first winding roller 11 , the second winding roller 21 and the first pressure roller 31 , until it, still partly wound, reaches a positioning downstream of the winding channel 7 so as to allow the first movable arm 32 to enter the channel 7 and make contact with a third core which has just reached the winding channel 7,

- cutting the web 6 being wound around the second core 5” or 105” and, simultaneously, expelling the second roll formed by the action of the second winding roller 21 and the second pressure roller 41 ,

- continuing cyclically with the steps just described for forming a third roll, fourth roll, fifth roll, etc.

Advantageously, each first 5’ or 105’ and second core 5” or 105” whichever it is, is moved (directly at the start and therefore by the roll of paper which is formed) by the action of at least three of the rollers 11 , 21 , 31 and 41 , between the initial position for winding the web of paper 6 and a final position of complete winding of the respective roll to be expelled, for the reasons already described, that is to say, to limit the risks of breakage of the paper.

In particular, in the initial position, the first winding roller 11 , the second winding roller 21 and the first pressure roller 31 exercise a simultaneous control of the roll of paper which is wound around the first core 5’ or the second core 5”, 105”, whilst the second winding roller 21 and the two pressure rollers 31 and 41 exercise a simultaneous control of the roll of paper which is wound around the first core 105’.

With reference to the above-mentioned drawings, as regards the machine 1 , Figure 1 shows the log being formed around the core 5’, controlled by the rollers 11 and 21 , as well as by the presser 41 .

Figure 1 shows that the pressure rollers 31 and 41 are not located symmetrically relative to the log, which, on the other hand, occurs in the same step in the alternative embodiment which refers to the machine 101 (see Figure 11 ).

Figure 2 shows a further step of the formation of the log, whilst the core 5’ is moving away from the winding roller 11 to make space for the lowering of the presser 31 : during this step, the log is controlled by the roller 21 and by the pressers 31 and 41 .

Subsequently, whilst the winding of the web 6 continues around the first core 5’ (Figure 3), the log being formed, again controlled by the rollers 21 , 31 and 41 , moves away from the first winding roller 11 as much as is sufficient to leave the space for the lowering of the presser 31 which slides on the profile of the log to reach the position for starting winding.

After reaching the end of the formation of the first roll, which will be expelled from the winding zone, a new core 5” is inserted in the channel 7 and the web 6 is simultaneously cut. At this moment the old log, wound around the core 5’, is finished and the web of paper 6 starts to be wound around the second core 5” (Figure 4). The expulsion of the roll wound around the first core 5' is controlled by the second winding roller 21 and by the second pressure roller 41 , whilst the first pressure roller 31 has now reached the initial position of the channel 7.

The core 5" reaches the centre line of the rollers 11 and 21 entering the channel 7, starting to form the new log around the second core 5", at the same time the presser 31 has in turn reached the starting winding position whilst the roll formed around the first core 5' is leaving the winding step (Figure 5).

Figure 6 shows the start of the step of winding the web 6 around the second core 5”, in an initial position of the channel 7. The winding is controlled by the rollers 11 , 21 and 31 . At the same time, the log relative to the first core 5’ is expelled.

In Figure 7 the winding around the core 5” has started, controlled by the rollers 11 , 21 and 31 ; during this first growing step, the presser 41 starts to lower.

The roll which is growing around the core 5” is still controlled by the two winding rollers 11 and 21 together with the pressure roller 31 . The presser 41 , on the other hand, is about to reach the exchange position with the presser 31 (Figure 8).

When the geometry of the presser 31 is unfavourable, the presser 41 will start to work, succeeding the pressure roller 31 : from this moment on, the log will be controlled by the two winding rollers 11 and 21 and by the presser 41 (Figure 9).

Lastly, Figure 10 shows how the winding around the core 5” has been controlled by the rollers 11 , 21 and 41 , as shown in Figure 1 : from this moment on the cycle resumes as illustrated (and described) in Figure 2.

With regard to the variant of the machine 101 , Figure 11 shows the log being formed around the core 105’ controlled by the winding roller 21 and by the pressure rollers 31 and 41 . As shown in Figure 11 , the axes S3, S4, S2 respectively joining the centre of rotation C5 of the core 105’ with the centres of rotation C3, C4 and C2 of the corresponding rollers 31 , 41 and 21 define two angles A, between the axes S3 and S2, and B, defined between the axes S4 and S2 (Figures 11 and 11 A).

According to this configuration, the angles A and B are substantially equal whilst the condition of symmetry of the pressure rollers 31 and 41 persists relative to the centre of motion of the core 105’ or 105”: this symmetry of the pressure exerted by the rollers 31 and 41 improves the stability of the system.

Figure 12 shows the end step of the formation, in which the log is always controlled by the rollers 21 , 31 and 41 , always under symmetrical pressure relative to the centre of rotation C5.

In Figure 13, the log is still forming around the first core 105’, whilst it is moving towards the final position of the channel 7, so much so as to leave the space for the lowering of the presser 31 . During this step, the log is still controlled by the roller 21 and by the pressers 31 and 41 .

Figure 14 illustrates the log of the core 105’ at the end of its formation, in a final position. Simultaneously, a new core 105” is inserted in the introduction channel 8.

During the time in which the core 105” arrives at the channel 7, in the initial step, that is to say, the processing step practically close to the initial position defined above, the presser 31 slides towards the start of the channel 7.

At the same time, the web of paper 6 is cut: at this moment, the old log relative to the first core 105’ is completed, the web 6 rewinds on the second core 105” just introduced and the formation of a new roll starts. The expulsion of the first completed roll is controlled by the roller 21 and by the presser 41 , whilst the presser 31 is reaching the winding starting position.

Subsequently, the second core 105” reaches the initial position of the channel 7, between the rollers 11 and 21 , starting to form the new log, whilst the first pressure roller 31 has reached the winding starting position, and the first roll formed on the first core 105’ starts the expulsion step (Figure 15).

At this point, the second roll continues its formation winding the web on the core 105”, in rotation about the axis 150”, controlled by the rollers 11 , 21 and 31. On the other side of the winding channel 7, the first roll, now completed, is expelled (Figure 16).

Figure 17 shows the growth of the log around the second core 105”, always controlled by the two winding rollers 11 and 21 together with the presser 31 . The presser 41 starts to lower towards the initial position of the channel 7.

With reference to Figure 18, in its formation the log of the core 105” is still controlled by the rollers 11 , 21 and 31 , whilst the roller 41 is about to reach the initial position of the winding channel 7 where it will start to control in turn the winding together with the presser 31 and the second winding roller 21 , leaving free the first roller 11 (Figure 19). When this occurs, therefore, the core 105” is moved into a second winding position, no longer in contact with the winding roller 11 .

Figure 20 shows the step of winding the roll around the core 105”, which continues controlled by the roller 21 and by the two pressers 31 and 41 .

Also in this case, the shape of the pressers 31 and 41 relative to the centre of rotation C5 of the core 105” is symmetrical and the considerations already made for the description of Figure 11 apply.

Lastly, Figure 21 illustrates the second roll which, now close to being completed, is about to finish its winding around the second core 105”, still controlled by the rollers 21 , 31 and 41 , before starting the step of exchanging between the pressure roller 31 and the winding roller 11 (see Figure 14).

From the above description it may be seen how the invention achieves the preset purpose and aims and in particular the fact that a machine is made for the production of rolls of paper material and relative winding process, which guarantees that the pressure rollers have a firm grip, in such a way as to complete the winding of the roll without the risk of breakage of the web of paper.

In particular, the control of the log rotating about the axis of rotation of the core by three rollers during the entire initial winding step, in which it is the first presser which controls the growing of the roll without problems of friction (shielding itself, towards the inside of the winding channel), guarantees to the machine and to the system the stability necessary to limit to a minimum, or even to completely eliminate, the vibrations which could put at risk the continuity of the web of paper to be wound.

Another advantage of the invention is due to the fact that, thanks to the action of the pressers described, the control of the winding will no longer be controlled by the profile of the secondary roller and it will therefore no longer be necessary to personalise the machine, changing, for example, the cradle, by acting on the speed of rotation of the second winding roller and on its opening relative to the first roller, depending on the diameter of the core to be wound and the final diameter of the roll to be formed. With the consequence of a facilitated control of the winding of the log.

Lastly, the use of means which are easily available on the market and the use of common materials makes the device economically competitive.

The invention can be modified and adapted in several ways without thereby departing from the scope of the inventive concept.

Moreover, all the details of the invention may be substituted by other technically equivalent elements.

In practice, the materials used, as well as the dimensions, may be of any type, depending on requirements, provided that they are consistent with their production purposes.