"PACKAGING MACHINE FOR PACKAGING ROLLS WOUND AROUND WINDING CORES"

Description

Technical Field

The present invention relates to packaging machines for packaging rolls of paper, for example tissue paper, such as toilet paper, kitchen towels or the like, or rolls of other web materials wound around tubular winding cores.

State of the art

In the paper converting and roll producing industry packaging machines are known for producing single or multiple packs of rolls. To wrap and package the rolls, some of these machines use sheets of plastic material, in particular polyethylene or the like. In these machines, a group of rolls, appropriately arranged in one or more rows and in one or more layers, are inserted into a sheet of plastic and subsequently moved forward by means of a conveyor through a folding station. In the folding sta- tion, the flaps projecting from both sides of the group of rolls are folded against the front surfaces of the rolls. At the exit of the folding station the pack thus obtained is made to pass through a sealing station which, by means of appropriate heating systems, heats and seals together the folded flaps of the plastic sheet. Machines of this type are commonly used to produce packs of multiple rolls, normally arranged in ad- jacent rows and if necessary in several superimposed layers.

In other machines of known type, each roll is packaged separately, wrapping it in a sheet of plastic, or more commonly paper. The flaps of the wrapping sheet, projecting from the flat faces of the roll, are folded and inserted in the axial hole of the tubular core, around which the roll is formed. With this system, rows of two or more rolls mutually aligned along the winding axis can also be packaged.

This packaging system typically goes by the name of "twist-and-tuck", as the flap of the wrapping sheet projecting from each side of the roll is twisted, and then pushed inside the axial hole of the tubular winding core of the roll. Machines of this type are described, for example in US-A-2,113,078, US-A-4651500 and in EP-A- 1518787. In particular, in the machine described in EP-A-1518787 the rolls are moved forward individually by means of a conveyor through a folding station. The flaps of the wrapping sheet, projecting from the two sides of the roll, beyond the front faces of the roll, are twisted around themselves, for example by means of a ro- _ . to-translational movement between two folding profiles. Subsequently, punches moving parallel to the axial direction of the rolls and provided with a reciprocating movement orthogonal to the direction of feed of the rolls, penetrate the tubular core of each roll and insert the previously twisted lateral flaps of the wrapping sheet into the tubular core.

The Italian patent application no. FI2011A000220, by the same applicant, describes a machine for packaging rolls configured to produce packs according to two different packaging techniques, specifically: by wrapping a group of rolls in a wrapping sheet, typically of thermoplastic material, with sealing of the folded flaps; or by a wrapping sheet, typically of cellulose material, which is wrapped around a single roll or group of rolls aligned axially, with a central winding core, in which the final flaps of the wrapping sheet are inserted by means of moving punches. This machine has a variable configuration with replaceable folding members, and a system for driving or feeding the rolls, adaptable to allow the production of two different types of pack.

In general, packaging machines based on the twist-and-tuck principle have some problems due to the stresses to which the wrapping sheet is subjected, in particular in the step of inserting the folded flaps thereof inside the tubular winding core. Moreover, in their extraction movement from the ends of the winding cores, the punches tend to draw the folded flaps of the sheet with them, making the last folding step not completely satisfactory and, in certain cases, giving rise to defective packs. Summary of the invention

According to one aspect, the invention intends to completely or partly solve one or more problems of prior art packaging machines, and in particular of twist-and- tuck packaging machines, or more generally of machines in which the projecting flaps of the wrapping sheet are inserted into the tubular winding core of the packaged roll.

To obtain more efficient packaging, the wrapping sheet folded inside the tubular winding core of the packaged roll is compressed by means of respective pins, which are inserted into the opposite ends of the tubular winding core after the wrapping sheet has been folded and inserted into the axial hole of the tubular winding core. Each pin is supported eccentrically by a motorized rotating shaft and is then made to rotate on the inner surface of the tubular winding core, obtaining a pack of _ _ better quality.

According to an embodiment, there is provided a packaging machine for packing rolls of material wound around a tubular winding core, comprising: an insertion station for inserting the rolls in wrapping sheets; a feed path of the rolls; a con- veyor for feeding the rolls along said feed path. A folding station can be provided along the feed path to wrap the rolls in the wrapping sheets. The folding station comprises, on each side of the feed path, at least one punch provided with an insertion and extraction movement with respect to the hole of the tubular winding core of the rolls to be packaged. The punch is advantageously provided with a rotating shaft, i.e. operated to rotate about its own axis. The rotating shaft of the punch supports an end pin, supported idle on the rotating shaft and rotatable about an axis substantially parallel and eccentric with respect to the rotation axis of the rotating shaft.

In practice, the pin can be supported at the terminal end of the rotating shaft, for example by means of a roller bearing.

In some embodiments, the rotating shaft, with the respective end pin supported idle thereon, can be associated with a disk-shaped member. The mutual position between the disk-shaped member and the rotating shaft with the respective pin is advantageously such that when the pin is inserted for the required length inside the axial hole of the tubular winding core the disk-shaped member presses on the corre- sponding flat face of the roll on which the wrapping sheet has been folded. The pressure of the disk-shaped member stabilizes the folds generated on the wrapping sheet, while the pin, rolling inside the axial hole of the tubular winding core and pressing against the sheet folded in the hole, stabilizes the inner folds.

The disk-shaped member can be fixed, or can be supported idle, or can be made to rotate by means of a suitable motorization.

In some embodiments, the disk-shaped member is mounted on a sleeve, inside which the rotating shaft of the punch is supported. The sleeve can be fixed, while the rotating shaft is rotatable inside the sleeve.

Preferably, folding members of the wrapping sheet are arranged upstream of the punch comprising the rotating shaft and the eccentric pin, to fold the portion of the wrapping sheet projecting with respect to the flat faces of the roll against these latter. For this purpose one or more stationary and/or dynamic folding profiles can be provided on each side of the feed path of the roll. _ _

In principle, only folding profiles that press the wrapping sheet against the flat faces of the roll could be provided, and a single punch provided with a rotating shaft with the respective pin mounted idle at the end thereof can be used to push the material of the wrapping sheet inside the axial hole of the tubular winding core. Prefera- bly, however, to obtain more gradual folding, reduce the risk of tearing or damage of the wrapping sheet and if necessary to obtain a more regular pack with a better appearance, according to advantageous embodiments, more than one punch is provided on each side of the feed path. The punches are arranged in sequence. For example, an additional punch can be provided upstream of the punch provided with the rotating shaft and with of the respective eccentric pin. In other embodiments, several additional punches can be provided upstream of the punch provided with rotating shaft. The additional punches can be fixed, i.e. non-rotating, or some can be fixed and some rotating or provided with a rotating shaft. One or more of these punches can also be provided in turn with an eccentrically mounted pin and optionally with a disk-shaped member.

In other embodiments, systems can be provided for closing the projecting flaps of the wrapping sheet which cause a twisting of the wrapping sheet, for example by means of two converging folding profiles. One or more punches can be associated therewith to insert the twisted wrapping sheet inside the axial hole of the wind- ing core. Finally, an end punch provided with rotating shaft with the respective eccentric pin mounted idle thereon can be inserted into each end of the tubular winding core, to complete packaging. The use of several folding profiles and/or several punches for inserting the wrapping sheet into the axial hole of the tubular winding core is particularly advantageous as it makes the pack more uniform and reduces stresses on the wrapping sheet, dividing the packaging process into several steps. Moreover, by providing a series of punches and/or folding members and an end punch with a rotating shaft and an eccentric pin, several rolls can be arranged in sequence inside the machine, performing a packaging process in sequential steps, operating simultaneously on several rolls. This increases the total productivity of the ma- chine.

Features and embodiments are described hereunder and further defined in the appended claims, which form an integral part of the present description. The brief description provided above identifies characteristics of the various embodiments of the _ _ present invention so that the following detailed description can be better understood and so that the contributions to the art may be better appreciated. Naturally, there are other characteristics of the invention which will be described below and will be set forth in the appended claims. It must be understood that the various embodiments of the invention are not limited in their application to the structural details and to the arrangements of components described in the following description or illustrated in the drawings. The invention can be implemented in other embodiments and put into practice in various ways. Moreover, it must be understood that the phraseology and terminology employed herein are purely for descriptive purposes and must not be considered limiting.

Therefore, those skilled in the art will understand that the concept on which the description is based can be used as a basis to design other structures, other methods and/or other systems to implement the various objects of the present invention. Consequently, it is important that the claims are considered as inclusive of those equivalent structures which do not depart from the spirit and from the scope of the present invention.

Brief description of the drawings

The invention will be better understood by following the description and accompanying drawing, which shows a non-limiting practical embodiment of the in- vention. More in particular, in the drawing:

Fig.l shows an axonometric view of an embodiment of a machine for packaging rolls with the twist-and-tuck system;

Fig.2 shows an axonometric view of the punches of the folding station of the machine in the configuration of Fig. l, from which the conveying system of the rolls and the folding members have been removed;

Fig.3 shows an axonometric view of one of the two groups of punches on one side of the feed path of the rolls;

Fig.4 shows a section according to the rotation axis of the rotating shaft; and

Figs. 5A-5E show a sequence of the folding procedure performed by the ma- chine of Figs. 1 to 4.

Detailed description of an embodiment

The detailed description below of examples of embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify _ _ identical or similar elements. Moreover, the drawings are not necessarily to scale. The detailed description below does not limit the invention. Rather, the scope of the invention is defined by the appended claims.

Reference in the description to "an embodiment" or "the embodiment" or "some embodiments" means that a particular characteristic, structure or element described in relation to an embodiment is included in at least one embodiment of the object described. Therefore, the phrase "in an embodiment" or "in the embodiment" or "in some embodiments" used in the description does not necessarily refer to the same embodiment or embodiments. Moreover, the particular characteristics, struc- tures or elements can be combined in any suitable manner in one or more embodiments.

In Fig. 1 the main machine members are shown. The load bearing structures, the casings, the parts of frame and other standard components have been omitted from the figure to highlight the functional and operating elements of the machine.

The machine, indicated as a whole with 1, comprises an insertion station 3 for inserting the rolls R. According to this exemplary embodiment, the insertion station 3 comprises an elevator 5 controlled by an actuator, not shown, for example an electronically controlled electric motor, interfaced with an electronic control unit, again not shown.

In this exemplary embodiment the rolls R reach the packaging machine 1 through a feed system, not shown, at a lower height with respect to the height at which the roll feed and packaging system is located. The elevator 5 transfers the rolls from the lower level to the upper level at which the members that perform packaging of the rolls are located. In the configuration illustrated, the machine packages each roll separately in a wrapping sheet. It must be understood that the machine can be adjusted to produce packs of different dimensions, for example comprising two or more axially aligned rolls R, wrapped in a single wrapping sheet.

Above the elevator 5 a conveyor is provided, indicated as a whole with 11 , which transfers the rolls lifted by the elevator 5 in the insertion station 3, toward a folding station, indicated as a whole with 13. In the example illustrated, the conveyor is provided with a system with a double flexible member, to be able to adapt the machine for the production of other types of packs, by means of a heat-sealed plastic wrapping sheet, according to techniques known to those skilled in the art. In other _ _ embodiments, where production of packs of different type on the same machine is not required, conveying or feed of the rolls can take place with a different and simpler system, for example with a simple endless chain that carries pushers or seats for feed of the rolls.

In the example illustrated, the conveyor comprises two pairs of flexible members parallel to each other. In particular, in the example illustrated the conveyor 11 comprises a first pair of flexible members 15 and a second pair of flexible members 17. In the example illustrated, the flexible members 15 and 17 are constituted by chains, but it must be understood that it is also possible to use a different type of flex- ible members, such as belts and in particular toothed belts.

In the example illustrated, each flexible member 15 is entrained around a pair of toothed wheels 19. In some embodiments, one of the toothed wheels 19 of each flexible member 15 can be motorized. For example, two wheels 19 supported by a common shaft can be motorized, while the other two toothed wheels 19 can be idle.

The flexible members 17 are also each entrained around a pair of toothed wheels 21. Also in this case, a toothed wheel 21 for each flexible member 17 is motorized. For example, two coaxial toothed wheels 21 can be motorized, while the remaining wheels can be idle. In a known way, the two pairs of flexible members 15, 15 and 17, 17 can be controlled by two electronically controlled electric motors inter- faced with an electronic control unit, not shown. In normal operating conditions, the speed of the two motors is synchronous so that the two pairs of flexible members 15, 15 and 17, 17 are fed at the same speed. The angular phase between the two pairs of flexible members 15, 15 and 17, 17 and the respective guiding wheels, idle and driving, can be adjusted by changing the phase between the position of the two motors that operate the two pairs of flexible members.

Between the flexible members 15 there are arranged cross-members 23 engaged with the respective ends thereof to the two flexible members 15 mutually parallel to one another. Likewise, between the flexible members 17 there are arranged cross-members 25, each constrained with the ends thereof to the flexible members 17. Each cross-member can advantageously be formed by a pair of mutually parallel bars. In this configuration, fixed to each pair of cross-members 23, 25 is a respective seat 81 which, as will be explained below, receives a roll, or a row of aligned rolls, and moves the rolls R along a feed path defined by the conveyor 11 and which passes _ _ through the packaging station. In this exemplary embodiment, the seats 81 are mutually equidistant. The pitch between consecutive seats 81 is equal to the mutual distance between the cross-members 23, 25 of each pair of consecutive cross-members.

The configuration of the conveyor 11 described here is particularly advanta- geous as it enables the seats to be replaced with others of different dimensions. Moreover, the system with two pairs of flexible members 15, 15; 17, 17 enables (as known to those skilled in the art) the conveyor to be equipped with other mechanisms for movement of the rolls to produce packs of other type.

Further, the innovative features of the subject matter described herein can also be incorporated in a packaging machine with roll conveyors or feed means different from those described above and illustrated in the figures. For example, the rolls could be fed by a simple endless flexible member, such as a chain or pair of chains, or a belt or pair of belts, to which roll engagement and feed members are constrained in a fixed or adjustable manner. In other embodiments, the conveyor can comprise two superimposed flexible members, between which the rolls are engaged and fed.

Extending underneath the conveyor 11 is a sliding surface 33 wherealong the rolls engaged in the seats 81 slide. The sliding surface 33 extends in the roll feed direction along a feed path P underneath the lower branch of the flexible members 15, 17. The surface 33 extends on one side of the insertion table 3 of the rolls R and along the folding station 13. On the opposite side of the insertion station 3, i.e. on the opposite side with respect to the lifting trajectory (arrow fl) of the rolls R by the elevator 5, is a pair of moving carriages 35 sliding in guides 37 carried by a fixed structure 39. A pair of connecting rods 41 moves the carriages 35 according to the double arrow f35, for the purposes described below. The movement of the connecting rods 41 can be imparted, for example, by an electric motor or by a pair of electric motors, by means of respective cranks, not shown.

Each carriage 35 carries a moving folding profile 47 that folds a first flap of the wrapping sheet wrapped around the rolls R lifted by the elevator 5, pressing it against the corresponding front surface of the roll.

In the exemplary embodiment illustrated, arranged on the opposite side of the insertion station 3, associated with the sliding surface 33, is a group of members that fold the flaps of the wrapping sheet during feed of the roll or rolls R by the conveyor 11. These folding members will be described in greater detail below and are arranged _ _ symmetrically on two opposite sides of the feed path P, as shown in particular in Fig.2.

In the folding station 13, two slides 53 sliding in respective guides 55 are arranged underneath the conveyor 11 (see in particular Fig.2). The guides 55 are inte- gral with a fixed load-bearing structure 57. In the embodiment illustrated, each slide 53 is constrained by means of a tie rod 59 to a respective rocker arm 61 A e 6 IB. The two rocker arms 61A, 61B, placed at the two sides of the feed path P of the rolls R, are pivoted about a respective axis A parallel to the direction of feed F of the rolls R engaged by the conveyor 11. The reciprocating rotation movement of the two rocker arms 61A, 61B is symmetrical and is imparted through bars 63A, 63B by an electric motor 65 fixed to the structure 57, to which the supports of the rotating shafts of the rocker arms 61 A, 6 IB are also fixed. The rocker arm 61 A extends from the opposite part of the rotation axis A with respect to the tie rod 59 to form an extension 62, to which the end of the respective bar 63 A is pivoted in 64. With regard to the rocker arm 6 IB, vice versa, the latter is hinged in 66 in an intermediate position between the axis A and the constraining point of the tie rod 59. The end of the bars 63A, 63B opposite the ends constrained to the rocker arms 61 A, 61B are hinged, at a common axis B parallel to the axes A, to a pivoting arm 67. Pivoting of the arm 67 according to the double arrow f67 is imparted by the motor 65. The arrangement described enables symmetrical movements to be imparted to the rocker arms 61 A, 6 IB by rotating the motor 65 with reciprocating motion. This movement causes the reciprocating movement of the slides 53 guided in the guides 55 with the purpose of folding the wrapping sheet, as will be explained below.

A beam or bar 91 is fixed on each slide 53. Punches 93 are fixed to each beam 91. In the example illustrated, four punches 93 carried by the respective beam 91 are provided on each side of the feed path P of the rolls R. The punches 93 are spaced from one another by a constant, optionally adjustable pitch, which corresponds to the pitch of the rolls R housed in the single seats 81 integral with the conveyor 11. In the embodiment illustrated, the punches 93 are fixed with respect to the corresponding beams 91.

One of the two beams 91 with the respective punches 93 applied thereto is illustrated separately for greater clarity in Fig.3.

In addition to the four fixed punches 93, downstream of the punches 93 with _ _ respect to the direction of feed F of the rolls R along the feed path P, on each beam 91 there is arranged a final punch, indicated as a whole with 92 and comprising an internal rotating member or shaft 94 associated with a disk-shaped member 95. The structure of the final punch 92 is illustrated in greater detail in Fig.4, which shows a section according to a plane containing the rotation axis of the respective internal rotating shaft 94.

As shown in particular in Figs. 3 and 4, each internal rotating shaft 94 is rotat- ingly supported in a sleeve 96 by means of bearings 98. The sleeve 96 is fixed, for example by means of a plate 96A, to the respective beam 91 and moves integral therewith.

The internal rotating member or shaft 94 can be made to rotate by any type of actuator. In the example illustrated, on each side of the feed path P of the rolls R, there is provided a respective motor 102 that transmits the rotation motion to the respective internal rotating shaft 94 by means of a belt 104 guided around a pulleys 106 and 108. A bevel gearbox 110 transmits the movement from the pulley 108 to the internal rotating shaft 94. This arrangement enables the beam 91, and consequently the internal rotating shaft 94, to be moved parallel to the rotation axis of the shaft 94 for the purposes explained below, maintaining the mechanical connection with the respective motor 102.

Different rotation systems of the internal rotating shafts 94 could also be used.

For example, the motor 102 could be mounted integral with the beam or bar 91 of the respective end punch 92 and move integral therewith. However, the arrangement illustrated in the drawing has the advantage of reducing the masses carried by the beams 91 and therefore the inertias in play.

In the example illustrated the disk-shaped member 95 is fixed with respect to the sleeve 96. In other embodiments the disk- shaped member 95 can be supported idle on the sleeve 96 or also directly on the internal rotating shaft 94.

The distal end of each internal rotating shaft 94, i.e. the end facing the feed path of the rolls, supports an end pin or tailstock 112. Preferably, the pin 112 has a shape with rotational symmetry. In the example illustrated, the pin 112 is partly frustum-conical (surface 112A) and partly cylindrical (surface 112B, see Fig.4) in shape. The pin 112 is mounted idle on the distal end 94 A of the internal rotating shaft 94 of the end punch 92, by means of suitable supports. In the example illustrated, the pin _ _

112 is supported by means of a bearing 114.

The pin 112 is mounted so as to be able to idly rotate about a rotation axis Y- Y substantially parallel to the rotation axis X-X of the internal rotating shaft 94. The axes X-X and Y-Y are eccentric. In Fig.4 the eccentricity between the two axes is in- dicated with E. As can be understood from Fig.4, with this arrangement, when the internal rotating shaft 94 of the end punch 92 rotates about the axis X-X under the control of the motor 102, the end pin 112 rolls on the inner surface of the tubular winding core A of the roll R inside which the same pin is inserted, as will be described in greater detail below.

The synchronous and symmetrical movement of the rocker arms 61 A and 6 IB causes a corresponding synchronous and symmetrical movement of the beams 91 with the respective punches 93, 92 on the two sides of the feed path P of the rolls R transferred through the machine by the conveyor 11. The movement of the beams 91 is synchronized with the feed movement of the conveyor 11.

As can be seen in particular in Fig. 1, a first stationary folding profile 101, which extends approximately parallel to the path of the rolls, is arranged between each beam 91 with the respective punches 93, 92 and the feed path of the rolls. The stationary profile 101 can be carried by a fixed structure of the machine, indicated with 103. A second stationary folding profile 105 is fixed to the same structure 103, on each side of the feed path P of the rolls R. The profile 105 has an edge shaped with two converging lead-in profiles, indicated with 105 A and 105B, which are connect with a substantially circular portion 105C of the edge of the profile 105. The converging edges 105 A and 105B are facing in the direction of arrival of the rolls R from the insertion station 3 and therefore converge in the direction of feed F of the rolls until reaching the circular portion 105C of the edge.

On each side of the feed path P of the rolls R, a moving folding profile 107 is arranged between the stationary folding profiles 101 and 105. The two moving folding profiles 107 are provided with a movement according to the double arrow fl07 in substantially vertical direction. The movement of the moving folding profiles 107 is synchronized with the feed movement of the conveyor 11. In the exemplary embodiment illustrated, the lifting and lowering movement of the moving folding profiles 107 according to the double arrow fl07 can be imparted, for example, by an electric motor through a connecting rod-crank mechanism or in another suitable way. _ .

The members described above perform a sequence of folding steps, which will be better understood also with reference to the sequence schematically illustrated in Figs.5A-5E, which show a roll R and the related wrapping sheet I in isolation, to illustrate the packaging process.

Each roll R to be packaged is lifted by the elevator 5 and inserted in the respective seat 81 located above the trajectory of the elevator 5. In this step a wrapping sheet I, preferably paper, wraps the top and the sides of the roll R (Fig.5A). Moving horizontal folding tables, one of which is visible in Fig.l and indicated with 52 (the other being positioned on the opposite side with respect to the lifting trajectory of the rolls R by the elevator 5), fold the vertical flaps of the wrapping sheet, so as to arrange them under the roll R. The roll is thus completely wrapped by the wrapping sheet I which, being longer than the axial length of the roll R, projects from both the flat faces of the roll. With a forward movement of the folding profiles 47, a first part of each of the flaps of the wrapping sheet I, projecting with respect to the flat surfac- es of the roll R, is folded on said flat surfaces. At the end of this step the roll is as represented schematically in Fig.l OB.

If the stationary folding profile 101 extends with the initial, preferably rounded edge thereof until it is above the elevator 5, in this first step the upper portion of the wrapping sheet is at least partially folded against the front surface of the roll. Preferably, as shown in the appended drawings, the stationary folding profile 101 is twisted in such a manner that in the initial part it does not fold the wrapping sheet, but only acts thereon in a subsequent step.

In the subsequent step, the conveyor 11 moves the roll R forward according to the arrow F, while the horizontal moving folding table 52 performs a movement syn- chronized and concordant with the movement of the same conveyor 11.

The conveyor 11 moves forward stepwise so as to carry each roll R inserted in the respective seat 81, and around which the wrapping sheet I has been wrapped, in front of each punch 93, 92 making each roll stop in each position corresponding to the punches 93, 92 to perform the operations described hereunder. It must be under- stood that normally in each moment of the packaging cycle all the seats 81 of the conveyor 11 are full and therefore at each step of forward movement of the conveyor 11 each punch 93, 92 performs an operation on a different roll R.

The stepwise forward movement of the conveyor 11 is synchronized with the _ _ reciprocating movement of the two beams 91 and therefore of the two series of punches 93, 92 arranged respectively on the two sides of the feed path P of the rolls R. This reciprocating movement is controlled by the electric motor 65 and coordinated with the lifting and lowering movement of the moving folding profiles 107.

As stated, all the seats 81 are normally full and each punch 93, 92 performs an operation at each step on subsequent rolls R. In the description below, a single roll will be considered and the operations performed thereon by the various machine members will be described, it being understood that these operations are performed in sequence on each roll engaged in the seats 81 of the conveyor 11.

In the first step of forward movement of the roll R, after it has been inserted in the seat 81 located above the elevator 5, the roll is made to pass between the two opposite stationary folding profiles 101. If these are twisted, downward folding of the upper part of the projecting flap of the wrapping sheet 1 starts. Preferably, the folding operation is completed when the roll is located between the punches 93 of the second pair (counting in the direction of forward movement), as described hereunder. In some embodiments, the stationary profile 101 can be shorter than represented in the drawing and start downstream of the position taken by the roll just lifted by the elevator 5, so as to start folding of the upper part of the wrapping sheet only after the roll R has started to move forward according to F along the feed path P. In other embod- iments, the stationary folding profile 101 can be as represented in the drawing, long and flat, in which case downward folding of the upper part of the flap of wrapping sheet starts immediately, when the roll R is inserted into the seat 81 by the elevator 5. In further embodiments, the stationary folding profile 101 can have a variable height, with a lower edge that lowers gradually, to obtain a gradual folding of the flap of wrapping sheet.

When the roll R has performed the first step of forward movement and is located between the punches 93 of the first pair, it is stopped temporarily, enabling partial insertion of the punches 93 inside the axial hole of the tubular winding core AV of the roll R and withdrawal from the tubular winding core. In this way, the punches 93 fold the portion of wrapping sheet I, which was folded by the moving folding profiles 47 against the respective front surface until it is over the tubular core AV, inside the tubular winding core AV (Fig.5B). Moving forward by a further step, the roll R is located between the punches 93 of the second pair, after the upper part of the flap of _ _ wrapping sheet projecting from each of the two front surfaces of the roll R has been folded downward by the respective stationary folding profile 101. The reciprocating movement of insertion and subsequent extraction of the punches 93 of this pair causes insertion of the respective portion of folded flap inside the tubular winding core AV (Fig.5C).

Once the punches 93 have been extracted from the tubular winding core AV of the roll R, this latter moves forward by a further step and is located at the two opposite moving folding profiles 107, which have been lowered to allow the roll to be positioned and are axially aligned with the punches 93 of the third pair of punches. If necessary, the forward movement of the rolls R and the lowering movement of the moving folding profiles 107 can be coordinated so that the roll R moves forward between the two moving folding profiles 107 which have been taken to the lifted position, to fold a part of the projecting flaps against the flat surfaces of the roll. Subsequently, the profiles 107 can be lowered and lifted again to fold the lower part of the flaps of wrapping sheet I against the flat surfaces of the roll R. Preferably however, the moving folding profiles 107 are lowered underneath the feed table of the rolls before the roll R arrives. When the roll stops in the position corresponding to the moving folding profiles 107, these are lifted to fold the lower portion of the flap of wrapping sheet projecting from the respective front surface of the roll R upward, pressing it against this surface and carrying it in front of the tubular winding core AV.

The lifting movement according to fl07 of the moving folding profiles 107 is synchronized with the transverse movement of the punches 93 carried by the beam 91, so that the punches 93 of the third pair of punches are inserted into the hole of the tubular winding core AV, which is located between the moving folding profiles 107 after said moving folding profiles 107 have been lifted. In this way one part of the flap of the wrapping sheet I is inserted inside the winding core AV. At this point the roll R is in the condition schematically shown in Fig.5D.

At the subsequent step, the roll R moves forward between the two stationary folding profiles 105, which fold, against the front surfaces of the roll R, the remain- ing portions of the flaps of wrapping sheet I, which are then inserted inside the axial hole of the winding core AV with a further penetrating movement of the last pair of punches 93. At this point, the roll is completely wrapped and the flaps of the wrapping sheet I have been overturned against the flat surfaces of the roll R and inserted _ _ into the tubular winding core AV (Fig.5E).

The next step of forward movement carries the roll between the two disk- shaped members 95 and the pins 112 carried by the rotating shafts 94 of the end punches 92. The pins 112 are inserted into the ends of the tubular winding core AV of the roll R by the approaching movement of the two end punches 92 and the beams 91 carrying them. During insertion, or when insertion has been completed, the internal rotating shafts 94 of the end punches 92 are made to rotate about the respective axes X-X. The position of the end punches 92, the dimension of the diameter of the pins 112 and the eccentricity E between the motorized rotation axis X-X of the inter- nal rotating shafts 94 and the axis Y-Y of idle rotation of the pins 112 are such that during rotation of the internal rotating shaft 94 the respective pin 112 rolls, with its cylindrical surface 112B, on the inner surface of the winding core AV, pressing against it the folded flaps of the wrapping sheet I, previously inserted into the axial hole of the tubular winding core AV.

This causes flattening of the wrapping sheet I and stabilizing of the folds obtained in the previously described steps, so as to stabilize the pack. The disk-shaped member 95 on each side of the feed path P presses against the respective front surface of the roll, stabilizing the folds of the wrapping sheet I in this area.

After a sufficient number of revolutions of the internal rotating shafts 94, these are extracted from the tubular winding core AV by a movement of the beams 91. The rotation movement can cease before extraction or preferably continue during extraction, facilitating the extraction movement of the pins 112 and reducing friction stress between the surfaces of the pins 112 and the wrapping sheet, in this way reducing the risk of the wrapping sheet I being drawn out of the hole of the tubular wind- ing core AV during the extraction movement.

The final pack that is obtained is similar to that obtainable with the packaging machines of the twist-and-tuck type known from the prior art described in the introduction of the present description. However, the method performed by the machine described here is different from those mentioned above, as there is no twisting or tor- sion of the projecting flaps of the wrapping sheet and subsequent insertion into the tubular winding core in a single operation by means of a single punch. On the contrary, the machine described gradually folds each wrapping sheet I, overturning a portion of sheet against the lateral surface of the roll R at each step of the roll and insert- _ _ ing only a part of the flap of folded wrapping sheet I inside the tubular winding core AV at each step. The "tuck" process, i.e. insertion of the sheet into the winding core by means of a punch, is therefore divided into a series of subsequent steps, using in sequence for each side of the roll four punches which each act on the same roll, one at each step. Insertion of the folded flap of the wrapping sheet into the tubular winding core AV is therefore much more gradual, which reduces the risk of tearing of the wrapping sheet I during packaging of the roll R. The rotating shaft 94 and the respective pins 112 with the optional disk- shaped member 95, enable optimal stabilization of the wrapping sheet, reducing the risk of the sheet accidentally exiting from the ax- ial hole of the tubular cores.

The subsequent step of forward movement of the conveyor 11 carries the packaged roll R to an extractor 120 (shown in particular in Fig.l), provided to extract the roll R from the respective seat 81.

The embodiments described above and illustrated in the drawings have been discussed in detail as examples of embodiment of the invention. Those skilled in the art will understand that many modifications, variants, additions and omissions are possible, without departing from the principles, concepts and teachings of the present invention as defined in the appended claims. Therefore, the scope of the invention must be determined purely on the basis of the broadest interpretation of the appended claims, comprising these modifications, variants, additions and omissions therein. The terms "comprise" and its derivatives do not exclude the presence of further elements or steps besides those specifically indicated in a given claim. The term "a" or "an" preceding an element, means or characteristic of a claim does not exclude the presence of a plurality of these elements, means or characteristics. When a device claim lists a plurality of "means", some or all of these "means" can be implemented by a single component, member or structure. The stating of given elements, characteristics or means in distinct dependent claims does not exclude the possibility of said elements, characteristics or means being combined with one another. When a method claim lists a sequence of steps, the sequence in which these steps are listed is not binding, and can be modified, if the particular sequence is not indicated as binding. Any reference numbers in the appended claims are provided to facilitate reading of the claims with reference to the description and to the drawing, and do not limit the scope of protection represented by the claims.