WO2004103819A1

WO2004103819A1 - Apparatus and process for packaging a pile of paper multilayer articles or the like

Info

Publication number: WO2004103819A1
Application number: PCT/EP2004/005502
Authority: WO
Inventors: Jozsefne Fuvesi
Original assignee: Aest-Trading Llc
Priority date: 2003-05-23
Filing date: 2004-05-21
Publication date: 2004-12-02
Also published as: ITFI20030146A1

Abstract

An apparatus and process for packaging a pile (P) of paper articles, such as serviettes, paper handkerchiefs, napkins and the like, comprises a feeding station (1) of the pile (P) to be packaged with a drawer device (13) for receiving the pile (P) pushed by a first horizontal pusher (12) and partially wound by a packaging sheet (F) . Axial folding and welding means (32, 33) of the sheet (F) are arranged downstream of the feeding station (1) and side folding and welding means (52, 53) are arranged downstream of the axial folding and welding means (32, 33) The apparatus also comprises transporting means (31, 34) of the pile (P) along a normal direction with respect to the working direction of the first pusher, and a second horizontal pusher (14, 35b, 36b) for pushing the pile (P) from the drawer (13) onto the transporting means (31, 34). The axial folding and welding means (32, 33) comprise a stationary folding assembly (32) and a welding assembly (33) arranged along the transporting means (31, 34).

Description

TITLE

APPARATUS AND PROCESS FOR PACKAGING A PILE OF PAPER MULTILAYER ARTICLES OR THE LIKE DESCRIPTION Field of the invention

The present invention refers to the field of the packaging of piled up multi-layer paper articles, such as serviettes, paper handkerchiefs, napkins and the like made from tissue-paper. In particular, it concerns an apparatus and process for packaging piles of said articles by means of a plastic packaging film.

Background of the invention

According to the prior art, apparatuses of this type adopt the general configuration described in the European patent application published with no. 1260437. In short, there is provided a station in which the same pile is received by a drawer device, which moves with reciprocating motion along the direction of progress of the articles, between a position of reception of a pile of products and a position of release. Upstream of the drawer, the pile is intercepted by a packaging sheet, unwound from a reel and cut to the correct length. In practice, the pile, compressed in the vertical direction by a presser device, is pushed by a pushing device through the plane on which the sheet lies, and is inserted into the drawer, defined by two spaced horizontal plates.

The drawer then moves towards the release position, and during such displacement a first pair of folds of the film is carried out on the two sides of the pile, through first side folding means. In the release position, two folding blades strike down vertically on the rear side of the drawer, carrying out the folding of the rear flaps of the packaging sheet around the pile, partially overlapping them and carrying out the welding thereof . The sheet thus takes up a tubular configuration.

The drawer then leaves the package partially formed and returns into the receiving position, to receive a new pile. The package is pushed forwards by a transportation system, firstly undergoing again the action of the aforementioned first folding means, which carry out a second pair of side folds, and then that of further stationary folding means, by which further side folds are formed. Finally, welding means complete the packaging, welding the overlapping folds on the two opposite sides .

The apparatus briefly described above has insurmountable limits in productivity, connected to the relatively long stop that the pile must undergo in the station where the tubular packaging is formed, in turn established by the working time of the two folding and welding blades. The folding and welding step along the axis of the tube represents an actual "bottleneck" , which prevents the machine from producing more than about 80 pieces per minute. Clearly, the economic implications are anything but negligible.

A further problem, less significant with respect to the previous one but still noticeable, concerns the welding operation, or rather the fact that the axial welding line of the tube cannot be positioned adjacent to the lower edge . The welding system according to the prior art, indeed, necessarily entails a substantial overlapping of the welding flaps, due to the low precision of the action of the blades and also due to the fact that, having to shorten the stop time as much as possible, the operation is carried out with the maximum speed and, to have a reasonable certainty that the welding is fairly secure, a relatively large surface is involved by the same welding. As a consequence, the above mentioned area cannot be used for applying the usual advertising or instructive print on the packaging, for fear that they might be illegible or in any case blemished. Precious useful space is thus lost. Moreover, there is greater consumption of material due to the extensive overlapping. Summary of the invention The object of the present invention is to solve the problems outlined above, providing an apparatus and process for the packaging of piles of paper multi-layer articles or the like, capable of ensuring a substantially greater productivity with respect to the machine of the prior art to which reference has been made above .

A particular object of the present invention is that of providing an apparatus and process of the aforementioned type, in which the positioning of all of the weldings on the package can be established substantially as desired, and in particular adjacent to the lower edge of the package, with a low degree of overlapping, and a consequent saving of material, and such as to allow a free positioning of the surface design of the package on all of the useful space of the package itself.

Such objects are achieved with the apparatus for packaging a pile of paper multi-layer articles or the like according to the present invention, the essential characteristics of which are defined in the first of the attached claims.

A process for packaging a pile of paper multi-layer articles or the like according to the present invention has the essential characteristics of attached claim 15. Brief description of the drawings

Characteristics and advantages of the apparatus and process for packaging a pile of paper multi-layer articles or the like according to the present invention will become clearer from the following description of embodiments thereof, given purely as non-limiting examples, with reference to the attached drawings, in which:

- figure 1 shows, through a schematic top plan view, the general layout of a packaging apparatus according to the invention, with a series of piles of products in successive steps of the packaging process;

- figures 2a and 2b are schematic section views of the apparatus in the zone of the supply station, taken along line II-II of figure 1, in respective successive steps of the process; figure 3 is a schematic side view of the apparatus, in the area where the axial folding is carried out, according to the arrow III of figure 1, with a series of piles in successive steps of the process;

- figures 4a to 4e are section views, respectively, according to lines a-a to e-e of figure 3, each carried out in correspondence to one of the piles represented in the said figure; - figure 5 shows a section view of the apparatus in the area of execution of the axial welding, taken along line V-V of figure 1 ; figure 6 shows a schematic side view of the apparatus in the area where the side folds are carried out, according to the arrow VI of figure 1, also in this case with some piles in successive steps of the packaging process; - figure 7 shows, by means of a partial top plan view similar to that in figure 1, the layout of a packaging apparatus according to a different embodiment of the invention; - figure 8 is a schematic side view of the apparatus according to arrow VIII of figure 7, with parts omitted for the sake of clarity; and figures 9 and 10 represent schematic section views of the apparatus taken along lines IX-IX and X-X, respectively.

Detailed description of the invention

With reference to figures 1 to 6 , and in particular to figure 1, an apparatus according to the invention comprises a feeding station 1 of the products to be packaged, assembled in piles or packs P, coming in succession from a transportation line 2. As can be seen also with the help of figures 2a and 2b, the station 1 substantially correspond to the configuration in the prior art mentioned in the introductory part. In fact, there is provided a vertical presser 11 for compacting the pile P, and a first pusher 12 which, actuated horizontally in a reciprocating manner, pushes the pile P from the transportation line 2 towards a packaging sheet F, held on a plane perpendicular to the pushing direction by support means (not shown) .

Along said pushing direction, downstream of the sheet F, there is a drawer 13 defined by two spaced horizontal plates 13a and 13b. The drawer 13, again according to the prior art, is suitable for receiving the pile P after the same, pushed by the pusher 12, has been intercepted by the sheet F. As can easily be understood from figure 2b, the two plates 13a and 13b fold the sheet F around the pile P, partially winding it around it.

According to the invention, the drawer 13 is steady on the horizontal plane, and the feeding station 1 comprises second pushing means, in this embodiment consisting of a second pusher 14 with horizontal reciprocating action, acting on the pile P in a normal direction with respect to the direction along which the previous pusher 12 works . The second pusher 14 pushes the pile P, with the sheet F partially wound on it, towards an axial folding and welding line 3 represented, besides again in figure 1, in figures 3 to 5. The two plates 13a and 13b of the drawer 13 have two central strip-like portions 15, slidable in a reciprocating manner in accordance with the second pusher 14 and operated in coordination with it through a mechanical transmission (not represented) . In the slidable portions 15 suction holes 16 are formed through which the portions themselves exert a pull, and a consequent guide action that hinders relative displacements between the sheet and the pile P, on the sheet F, during the transportation of the pile on the line 3.

With particular reference to figures 3 to 5, the axial folding and welding line 3 comprises conventional motorised conveyor belts 31, arranged in pairs above and below the piles P and engaged by friction (and possibly with the help of suction means, not shown, analogous to the aforementioned holes 16) with the relevant faces of the piles.

The line 3 also comprises, proceeding from upstream to downstream with respect to the transportation direction, a stationary folding assembly 32 and a welding assembly 33, arranged in succession adjacent to the conveyor belt 31, at the same side of the first horizontal pusher 12. The folding assembly comprises two trapezoidal blades 32a and 32c and a triangular blade 32b, arranged vertically so as to define two consecutive folding grooves 32d, 32e, with ascending and descending progression respectively (see, in particular, figure 3), all according to a configuration which is known as such. Equally known is the structure of the welding assembly 33, with a fixed welding rod 33a arranged inside a conveyor belt 33b, which, operating laterally, contributes to the transportation of the piles P. The belt 33b, made of Teflon^®, transfers the heat continuously from the rod 33a to the piles P, or rather to the sheet F in the area in which the welding must be carried out . At the end of the axial folding and welding line 3, the conveyor belt 31 unloads the piles P on an intermediate station 4, where they are moved by a third horizontal pusher 41, working along the same direction as the first pusher 12, and thus perpendicular to the line 3. As shown in figure 6, the third pusher 41 has, as well as a conventional flat base 41a for abutment on the pile to be moved, two shaped fins 41b projecting perpendicularly from the base 41a, along two opposite side edges thereof. The shaped fins 41b, as will be explained more clearly hereafter, are suitable for engaging with the sheet F at the same time as the pushing of the flat base 41a on the pile P, in order to carry out two side folds on the sheet itself .

Downstream of the intermediate station 4, of course along the working direction of the third pusher 41, a side folding and welding line 5 finally extends, in turn comprising stationary folding assemblies 52 and welding assemblies 53, in this case, however, arranged in pairs on both sides of a transportation system 51. The folding and welding assemblies 52, 53 adopt the same configuration - which, as stated, is conventional - as the assemblies 32 and 33 of the axial folding and welding line 3. Therefore, in figure 6 blades 52a, 52b and 52c can be seen spaced apart so as to define grooves 52d, 52e, and in figure 1 rods 53a can be seen in the relative conveyor belts 53.

A working cycle of the apparatus according to the invention is carried out as follows. It has already been cleared how, in a substantially conventional manner, the first horizontal pusher 12 pushes a pile P in the drawer 13. In this condition two flaps Fa and Fb of the sheet F project from the pile P, and also from the drawer 13, in the direction of the pusher 12. Other flaps of the sheet F extend from the pile P laterally, i.e. in a direction transversal to the movement of the pusher. Such flaps, indicated at Fc, are visible in figure 1 and in the first pile P from the left of figure 3, being omitted in the successive piles of the series for the sake of clarity.

The operation of the second horizontal pusher 14, with simultaneous sliding of the sliding portions 15 of the plates 13a and 13b of the drawer 13, causes the transfer of the pile P on the transporters 31 of the axial folding and welding line 3. As anticipated above the sliding portions 15, thanks also to the relative suction holes 16, carry out a guiding action, keeping the sheet F and the pile P well compacted and without any mutual displacement during transportation. When the transportation has been completed, the sliding portions 15 go back into the starting position, the turning off of the suction ensuring the disengagement from the sheet F. The flaps Fa and Fb of the sheet F thus interfere with the blades of the folding assembly 32, being thus folded as represented in figure 3, and in figures 4a to 4e. In particular, the ascending groove 32d firstly causes a folding upwards of the lower flap Fb (figures 4b and 4c) , then the descending groove 32e makes the upper flap Fa fall (figures 4d and 4e) , and overlap the lower flap Fb.

Still under the action of the transporting system, the pile P then immediately passes to the welding assembly 33, which applies an axial welding line onto the overlapping flaps Fa and Fb, at a suitable height. The sheet F thus takes up a tubular configuration with open ends, from which ends the side flaps Fc extend. In such a configuration the pile P receives the action of the third horizontal pusher 41 in the intermediate station 4.

The flaps Fc are then firstly tucked in along the vertical edges, respectively by the fins 41b of the pusher 41 and by the shaped ends of the triangular blades 52a of the two folding assemblies 52 of the line 5. The grooves 52b and 52e complete the folding, working on the flaps Fc along the upper and lower edges of the pile P (see figure 6) . This final step, which again, considered as such, substantially corresponds to what already provided in known machines, ends with the application of the side weldings by the assemblies 53.

In order to assure an even safer placement of the piles P along the axial folding and welding line 3, with simultaneous precise pre-formation of a sheet F with respect to its pile, nevertheless permitting a convenient and automatic fitting of the line to size variations of the pile P, the advantageous configuration of figures 7-10 may be adopted. Reference will be made hereafter to said figures, bearing in mind that all the parts which are analogous or equivalent to the previous embodiment will not be described again nor designated again with different numerals .

According to this configuration there is provided, replacing the transportation belts 31 on the lower side (figure 5) , and the second pusher 14 (figure 1) , a double chain conveyer 34 running between two deviation axis X and Y respectively upstream of the feeding station 1 and of the intermediate station 4. More precisely, the conveyer comprises two parallel and adjacent chains 35, 36 driven independently to each other, by respective drive gears 35c, 36c on the rear axis X (figure 7) , in their turn receiving a step by step operation by two servomotors, not shown.

A succession of radial arms 35a, 36a radially extend from each chain 35, 36. The arms 35a, 36a are equally spaced along the respective chains and each of them integrally supports a folder plate 35b, 36b arranged orthogonally to the progress direction of the piles, i. e. so as to exert a restraint action on the transverse rear or front sides of the same piles, as clarified shortly.

As can be seen in particular in figures 9 and 10, the folder plates 35b, 36b have such a size that they do not interfere either with the axial folding and welding assemblies 32, 33, or with the shaped fins 41b of the pusher 41, or with the horizontal fixed plates 13a and 13b of the drawer 13 between which the movable folder plates 35b, 36b must be able to pass without any hindrance. To this purpose, two slots 13c are formed in the lower plate 13b, allowing the support arms 35a, 35a to slide across the same plate 13b (figure 9) . The same function (figure 10) is afforded by slots 43c formed in a lower plate 43b which according to this embodiment, in cooperation with an upper plate 43a, defines a pile-containment drawer device also in the intermediate station 4.

In further detail, the folder plates 35b of a first chain 35 are fit for containing the piles P on the rear side, and can be distinguished for the use of a less marked line in figures 7 and 8. On the contrary, the folder plates 36b of the second chain 36, represented with a more marked line, contain the piles on the front side.

When working, the first chain 35 with the rear plates 35b is arranged in such a way that, in each stop between an operation step and the following one, a plate 35b is perfectly in line with the rear side of a pile about to be fed to the line by the pusher 12 of the feeding station 1 (in this case, the sole pusher in the said station) . The alignment is clearly shown in figure 7, where it is made clearer by the reference line indicated at R. In the same stop, a front plate 36b of the second chain, previously timed to this purpose, is perfectly in line with the front side of the same pile P, so as the latter is precisely housed between two folder plates.

The operation step of the two conveyer chains, timed to each other, will push the pile forward along the line, clearing the space for the subsequent feeding. As the pile moves forward, it is always securely and firmly between two subsequent plates, even in the intermediate station 4 and under the action of the relevant pusher 41. Consequently, the folder plates 35b, 36b sum up both the function of transporting means of the piles along the line 3, in cooperation with the upper belts 31, and that of pushing means of the piles P out of the drawer 13 (in this they replace the second pusher 14 of the previous embodiment) . Moreover, the plates 35b, 36b, when receiving the pile P with the sheet F, provide also for a first folding of the relevant side flaps Fc .

When it is necessary to adapt the apparatus to piles having a different size, that is a different length measured along the progress direction of the axial folding and welding line, it is sufficient to adjust the position of the second chain 36 by controlling the relevant drive, while the first chain 35 is kept stationary. The front plates 36b can thus be displaced of the required amount. If, for instance, the new size is longer as shown by the broken outline P in figure 7, the front plates 36b will be displaced forward with respect to the rear plates 35b. At the start of the normal working the two chains 35, 36 will resume their mutually timed paces, as described above. The length of the predetermined progression step will be clearly greater than the maximum size which can be by treated by the apparatus. Clearly, when shifting to differently sized piles, as it has just been described, the side folding and welding line 5 will have to be adjusted in order to be compatible with the new size.

Clearly, the apparatus according to the invention offers the fundamental advantage, with respect to a known machine of the type to which reference has been made above, of avoiding the long stop required to carry out the axial folds by the vertically operated blades, and to apply the relative welding. Such working steps are carried out, according to the invention, on the piles P moving along the line 3, by the assemblies 32 and 33. In practice, the productive flow becomes continuous, the two stops in the feeding station 1 and in the intermediate station 4 being negligible. The productivity can therefore undergo a substantial increase, being able to reach values up to 140 packaged pieces per minute. Moreover, the axial welding means, i.e. the rod 33a, have a position that, once adjusted, is kept fixed in height, for which reason the welding line can be arranged in a precisely foreseeable manner, in particular near to the lower edge of the package. A contribution to such a result is given by the fact that the welding operation is carried out at relatively low speed and with a smooth linear movement, without the knocks and abrupt movements of the flaps of the film which occur following the action of the blades of conventional apparatuses. It is thus possible to have a precise, accurate and certain result with a much reduced overlapping of the flaps (even less than 50% with respect to the prior art) . The whole surface of the sheet F, i.e. also the one intended to coat the face of the axial welding, can thus be usefully used for printing the surface design of the package, moreover with a substantial saving of film.

A further advantage derives from the substantially L-shaped layout of the apparatus according to the illustrated embodiments, determined by the fact that the axial folding and welding line 3 and the side folding and welding line 5, to avoid a rotation of the pile P in the intermediate stopping station (an option which is, however, theoretically feasible) , must be perpendicular to each other. Such a layout, indeed, entails the presence of the third horizontal pushing means 41 to move the piles P between the two lines, for which reason the fins 41b incorporated in it replace the independent folding mechanisms which, in the known solution, are intended for the same function, and which determine a clear constructive complication. Still from the point of view of the structural and functional simplification, it must also be highlighted that the drawer 13 in this case is not equipped with the alternative motion which, in the conventional machine, is used to make the piles P undergo the action of the axial folding and welding blades.

As mentioned many times above, the various transporting and moving means, and relative means of actuation, as well as the folding and welding assemblies, have, when considered as such, totally conventional characteristics, being commonly used in the field and well known by any man skilled in the art. Variants and/or modifications can be brought to the apparatus and process for packaging a pile of paper multilayer articles or the like according to the present invention without for this reason departing from the scope of protection of the invention itself.

Claims

1. Apparatus for the packaging of a pile (P) of paper articles, such as serviettes, paper handkerchiefs, napkins and the like, comprising: a feeding station (1) comprising first pushing means (12) with horizontal action suitable for pushing a pile (P) to be packaged towards a packaging sheet (F) held in a substantially vertical plane, and a drawer device (13) for receiving said pile (P) pushed by said first pushing means (12) and partially wound by said sheet (F) ; axial folding and welding means (32, 33) arranged downstream of said feeding station (1) , for folding and welding flaps (Fa, Fb) of said sheet (F) projecting towards said first horizontal pushing means

(12); and side folding and welding means (52, 53), arranged downstream of said axial folding and welding means (32, 33) , for folding and welding flaps (Fc) of said sheet (F) projecting sideways with respect to the working direction of said first pushing means (12) , characterised in that it also comprises: transporting means (31, 34) arranged between said feeding station (1) and said side folding and welding means (52, 53) for transporting said pile (P) horizontally along an orthogonal direction with respect to the working direction of said first pushing means (12), said transporting means (31, 34) comprising, or being associated to, second horizontal pushing means (14, 35b, 36b) for pushing said pile (P) out of said drawer device (13) and onto said transporting means (31, 34), said axial folding and welding means (32, 33) comprising a stationary folding assembly (32) and a welding assembly (33) arranged along said transporting means (31, 34) and suitable for operating in succession on said sheet .

2. Apparatus according to claim 1, comprising third horizontal pushing means (41) for pushing said pile (P) at the end of said transporting means (31, 34) towards said side folding and welding means (52, 53), said third pushing means (41) having a working direction which is normal to the direction of said transporting means (31, 34) .

3. Apparatus according to claim 2, wherein said third horizontal pushing means (41) are arranged in an intermediate stopping station (4) , arranged between said transporting means (31, 34) and a side folding and welding line (5) along which said side folding and welding means (52, 53) are arranged.

4. Apparatus according to claim 3 or 4 , wherein said third horizontal pushing means comprise a flat base (41a) for abutment on the pile (P) to be pushed and two shaped fins

(41b) projecting perpendicularly from said flat base (41a) along two opposite side edges thereof, said shaped fins

(41b) being suitable for engaging with said sheet (F) at the same time as the pushing of the flat base (41a) on the pile (P) to carry out two side folds on the sheet (F) itself.

5. Apparatus according to any of the previous claims, wherein said axial folding assembly (32) comprises a plurality of folding blades (32a, 32b, 32c) arranged vertically spaced apart from each other, so as to define two consecutive folding grooves (32d, 32e) , with ascending and descending progression, respectively, intended for folding respective lower and upper flaps (Fb, Fa) of said sheet (F) .

6. Apparatus according to any of the previous claims, wherein said drawer device (13) comprises guide means (15) slidable in a reciprocating manner along the working direction of said second pushing means (14, 35b, 36b), in coordination therewith, said guide means (15) being capable of exerting a pulling force on said packaging sheet (F) partially wound on said pile (P) , so as to hinder the mutual displacement between the sheet (F) and the pile (P) .

7. Apparatus according to claim 6, wherein said drawer device (13) comprises a lower plate (13b) and an upper plate (13a) , said guide means (15) comprising respective sliding portions of said plates (13a, 13b) , and a plurality of suction holes (16) formed in said sliding portions, for exerting a pulling action on said packaging sheet (F) .

8. Apparatus according to any of the previous claims, wherein said axial welding assembly (33) comprises a fixed welding rod (33a) supported inside a conveyor belt (33b) engaging with said pile (P) , said belt (33b) being made of a material suitable for transferring the heat from said rod (33a) to said pile (P) .

9. Apparatus according to any of the claims from 3 to 8 , wherein said transporting means (31, 34) comprise chain conveyer means (34) running with a step by step drive between said feeding station (1) and said intermediate station (4) , said second pushing means (35b, 36b) comprising a plurality of folder plates (35b, 36b) integral with said chain conveyer (34) , capable of passing within said drawer device (13) , spaced so as to house and transport said pile (P) contained in a stable manner between two consecutive folder blades (35b, 36b) , and to form first side folds on said sheet (F) when said pile (P) is fed to said chain conveyer (34) by said first pushing means ( 12 ) .

10. Apparatus according to claim 9, wherein said conveyor chain means (34) comprise two chains (35, 36) driven in a coordinated but independent manner, said chains (35, 36) supporting respective series of folder plates (35b, 36b) for containing said piles (P) respectively on the rear side and on the front side, the chain (35) with the rear side plates (35b) being driven in such a way that in each stop between an operation step and the following one, a rear folder plate (35b) is always in line with the rear side of pile (P) being fed by said first pushing means

(12) , the chain (36) with the front side plates (36b) being preliminarily adjustable with respect to the other chain (35) , as a function of the size of the pile, so that a front plate (36b) is always in line with the front size of said pile (P)

11. Apparatus according to claim 10, wherein said folder plates (35b, 36b) are integral with respective arms (35a, 36a) radially extending from respective chains (35, 36) , slots (13c) being formed in said drawer device (13) for letting said arms (35a, 36a) slide across said drawer.

12. Apparatus according to claim 11, wherein said intermediate station (4) comprises an upper plate (43a) and a lower plate (43b) for containing said pile (P) , slots (43c) being formed in said lower plate (43b) for letting said arms (35a, 36a) slide across said plate.

13. Apparatus according to any of the previous claims, wherein said transporting means (31) comprise motorised belts (31) , arranged in pairs at least above said pile (P) and engaged by friction with it .

14. Apparatus according to claim 13, wherein said transporting means (31, 34) also comprise suction means suitable for exerting a pulling action on said packaging sheet (F) .

15. Packaging process of a pile (P) of paper articles, such as serviettes, paper handkerchiefs, napkins and the like, comprising: a step of feeding said pile (P) to be packaged, wherein said pile (P) undergoes a horizontal push towards a packaging sheet (F) held in a substantially vertical plane, and wherein it is received by a drawer device (13) , partially wound by said sheet (F) ; an axial folding and welding step of said sheet (F) , wherein flaps

(Fa, Fb) of said sheet projecting in the direction of said push are folded and welded; and a side folding and welding step of said sheet (F) , wherein flaps (Fc) of said sheet projecting laterally with respect to the direction of said push are folded and welded, characterised in that in said axial folding and welding step said pile is transported horizontally along a normal direction with respect to that of said push, so as to intercept in succession a stationary folding assembly (32) and a welding assembly (33) , operating on the pile itself whilst it is kept in motion.

16. Process according to claim 15, wherein in said side folding and welding step said pile (P) is transported along a horizontal direction parallel to that of said push.

17. Process according to claim 16, wherein between said supply step and said welding step and axial folding, and between the latter and said axial folding and welding step, said pile undergoes respective further horizontal pushes, each in a normal direction with respect to the previous push.

18. Process according to claim 17, wherein between said axial folding and welding step and said side folding and welding step said pile undergoes a stop in which, at the same time as the relative push, two first side folds are carried out on said sheet .

19. Process according to any of the claims from 15 to 18, wherein said transport in the axial folding and welding step is carried out maintaining said pile (P) stably contained between two parallel surfaces abutting respectively on the front and on the rear side of the pile.