WO2013156913A1

WO2013156913A1 - Machine and method for making round boxes

Info

Publication number: WO2013156913A1
Application number: PCT/IB2013/052925
Authority: WO
Inventors: Mauro Mazzinghi
Original assignee: Emmeci S.P.A.
Priority date: 2012-04-17
Filing date: 2013-04-12
Publication date: 2013-10-24
Also published as: ITBO20120213A1

Abstract

A machine for making round boxes comprises a folding station (108) configured so as to perform folding of a blank (1 ) along a curved trajectory so as to bring opposite edges (3, 3'; 4, 4') of the blank (1 ) into end-to-end contact with each other, thus defining a joining line (G), and a gluing station (105) designed to release onto the blank (1 ) a layer of glue for sealing the joining line (G) and configured to release the layer of glue onto the blank (1 ) along a direction defining, once the blank (1 ) has been folded, an at least partly helical trajectory.

Description

TRANSLATION (RULE 12.3) 1 12 April 2013

DESCRIPTION MACHINE AND METHOD FOR MAKING ROUND BOXES

Technical field

The present invention relates to a machine and a method for making round boxes, in particular for forming the round side wall of said type of boxes.

Background art

"Round box" is understood as meaning, in general, a box with a rounded side wall.

More particularly, "round box" is understood as meaning a box with a cylindrical side wall which does not have sharp corners and has a given axial height.

It is currently known to form the aforementioned round walls using sections of tubes which are suitably cut to the desired length corresponding to the axial height of the box.

These tubes, which have a constant length and weight, are in turn formed by winding two or more continuous paper strips, which are staggered relative to each other, around a mounting spindle with a spiral movement. This operation is performed using special machines, called "tube-forming machines" or "spiralling machines" which operate continuously unwinding the strips from respective reels.

The spiralling machines, therefore, owing to their particular nature, operate continuously and therefore form a continuous tube with a diameter and thickness which are adjustable as required (typically from a diameter of a few millimetres and thickness of a few tenths of a millimetre to diameters of tens of centimetres with thicknesses of several millimetres). The continuous tube output from the spiralling machine is divided into sections of predetermined length depending on the subsequent applications, which may consist for example in immediate use for manufacturing boxes (and in this case the cutting length will be in relation to the desired length of the box or multiples thereof) or transportation on lorries to users who then further divide up the tubes into shorter sections (and in this case the cutting length will be compatible with transportation in the loading compartment of a lorry).

In any case, the manufacture of round boxes from sectioned tubes involves problems and high transportation and storage costs because of the large dimensions compared to the small amounts of material. In fact, the transportation or storage of the tubes results in occupation of very large volumes albeit with small-size objects.

Moreover, since the strips must be wound around the mounting spindle, the currently known tube-manufacturing machines cannot be easily adapted to a change in format (in particular to a variation in the diameter of the tube) since this would requires stoppage of the machine, replacement of the spindle with a spindle of different diameter and restarting of the machine. There exist therefore evident logistical and production-related difficulties associated with these format-changing operations.

Furthermore, an increase in the formats required results in an increase in the number of spindles which must be readily available. This means that, on the one hand, it is difficult to ensure an optimum production flexibility based on a wide range of formats, while on the other hand it is technically impossible to choose, as required, the format which is dependent on the diameters alone of the spindles equipping the machine.

These limitations and consequent disadvantages associated with the tube- forming spiralling machines and therefore the tubes produced have a negative impact on the systems for manufacturing round boxes which are dependent on the supply of tubes from which the sections for making the boxes are to be obtained.

In particular, the logistical difficulties involved in the storage and handling of tubes of such a size and the lack of versatility of the existing formats means that it is preferable to find an alternative solution to that of manufacturing round boxes using tubes.

Other technologies aimed at producing cylindrical paper walls, for example in the sector of cigarette-manufacturing machines, are known. In this case also continuous processes are used, these being based on a continuous strip of single-layer paper which is gradually closed up by winding it in the form of a cylinder having an axis parallel to the length of the strip with joining together of the two side edges of the strip along a generatrix of the cylinder itself.

Clearly these technologies do not apply to the box-manufacturing sector. Moreover, even if these technologies were to be applied to the box- manufacturing sector in order to manufacture continuous tubes with round (i.e. cylindrical) walls, the problems already mentioned with regard to spirally wound tubes would inevitably arise.

The problems arising from the use of continuous tubes which are then divided up could be partly overcome by making boxes with round walls from rectangular blanks, winding them in the form of a cylinder having an axis parallel to the length of the strip with joining together of the two side edges of the strip along a generatrix of the cylinder itself.

However, in this case too there would be a number of drawbacks.

In fact, if on the one hand folding a cylindrical blank in order to form the cylindrical wall of a round box would overcome the logistical and industrial difficulties associated with use based on continuous tubes which are then divided, on the other hand the problems associated with a change in format would not be solved and further problems would arise.

These rectangular blanks would be wound onto a spindle until the opposite edges of the blank mate with each other and these edges would then be sealed in order to obtain the side wall of the box.

However, joining together of the said opposite edges would be seriously affected by problems of lack of continuity in the curvature along the joint of the edges. The result is that the tubular article thus obtained would assume a pear-like and not a circular cross-section as is instead desired. Moreover, the need to use a spindle would pose the same problems associated with the change in format mentioned above.

Some examples of known systems for erecting round boxes from blanks are disclosed in patent documents US3439589A, DE1288416B and DE2847727A1 .

Disclosure of the invention

In the light of that mentioned above, the object of the present invention is to provide a machine and a method for making round boxes which overcomes the drawbacks of the prior art mentioned above.

In particular, the object of the present invention is to provide a machine and a method for making round boxes which can be used to obtain boxes having a perfect cylindrical form and large tolerances.

Another object of the present invention is to provide a machine and a method for making round boxes which are able to achieve a high degree of manufacturing flexibility, in particular with regard to the change in format and in particular the production of small batches.

Said objects are fully achieved by a machine and a method according to the present invention which are characterized by the contents of the claims indicated below.

In particular, the machine according to the present invention is a machine for making round paper or cardboard boxes, comprising:

- means for feeding a blank along a feeding path;

- a folding station arranged along said feeding path and configured to perform folding of the blank along a curved trajectory so as to bring opposite edges of said blank into end-to-end contact with each other, thus defining a joining line;

- at least one gluing station for releasing onto said blank a layer of glue for sealing said joining line.

It should be noted that said paper or cardboard box comprises a side wall and a bottom wall.

Since the box is round, the side wall is curved and the bottom wall has a corresponding curved line as perimeter.

In particular the side wall is cylindrical and the bottom wall is a circular disc.

According to the invention, the machine comprises a gluing station configured in such a way as to (or comprises gluing means configured to) release a layer of glue onto the blank along a direction defining, once the blank has been folded, an at least partly helical trajectory in order to perform closing of a corresponding at least partly helical joining edge.

In particular, the folding station is configured to perform folding of the blank along a circular trajectory.

In principle, this trajectory could also be elliptical or with any other form

(but preferably such that the side wall of the box, which is formed from the blank, has generatrices parallel to each other).

However, below, reference will be made in particular to the case where this trajectory is circular (so that the side wall of the box is cylindrical).

Therefore, said folding station is configured to perform folding of the blank along a circular trajectory around a folding axis.

In this respect, said first gluing station is configured to release said layer of glue onto the blank along a segment transverse, i.e. not parallel to said folding axis.

It should be noted that, preferably, the means for feeding the blank are configured so that said blank feeding path is parallel to a plane perpendicular to said folding axis; namely, the blank is fed to the folding station parallel to a plane perpendicular to said folding axis.

In this respect, it should be noted that preferably this gluing station is configured so as to release the layer of glue onto the blank along a segment transverse (and not perpendicular) to a blank feeding path. This segment, once the curvature of the blank has been formed to obtain a cylindrical configuration, is arranged along a helical trajectory. In particular, preferably, said gluing station is configured to release the layer of glue onto the blank along a segment transverse (and not perpendicular) to a blank feeding path, said segment having at least a (first) straight stretch inclined by a predetermined angle with respect to the blank feeding path.

More preferably, the gluing station is configured to release the layer of glue onto the blank along said (first) straight stretch inclined by a predetermined angle with respect to the blank feeding path and onto a second straight stretch perpendicular to the blank feeding path.

Preferably, said first gluing station is arranged upstream of the folding station with respect to said feeding direction.

It should be noted that the folding station is configured so as to fold the blank along said curved (preferably circular) trajectory, keeping the blank itself spaced (at a predetermined, preferably constant distance) from said folding axis.

Preferably, this gluing station comprises a glue dispenser arranged above a surface for conveying the blank and movable simultaneously with feeding of the blank so as to assume the same speed of feeding of the blank during release of the glue onto the blank. The glue may therefore be released without interrupting feeding of the blank.

The folding station comprises a gripper designed to grip an end portion of a blank and movable along a circular trajectory so as to impart to the end portion of the blank a circular trajectory. This system allows the blank to be pulled into the folded condition without the need for a central mounting spindle.

In particular, the gripper is mounted on a rotatable support having an axis of rotation parallel to the conveying surface.

Preferably, the rotatable support rotates about the folding axis.

Preferably, the gripper is movably connected to the rotatable support so as to vary the distance of the gripper itself from the axis of rotation of the rotatable support, i.e. from the folding axis. This adjustment allows the diameter of curvature of the blank to be selected as required from a range between a minimum diameter and a maximum diameter. Depending on the type of adjustment this diameter may be continuously varied (for example by means of a screw/female thread system).

The rotatable support is in turn mounted adjustably on a fixed frame so as to vary the distance of the axis of rotation of the rotatable support from the conveying surface. This allows the trajectory of the gripper to be kept always tangential to the support surface or in any case close thereto.

In order to assist curving of the blank in the folding station, the folding station also comprises guide means arranged along the (circular) trajectory defined by the movement of the gripper.

Preferably, these guide means comprise a pair of rollers: an inner roller and an outer roller which are configured to keep the blank slidably inserted there; i.e. inserted between the two rollers.

Preferably, at least one of the two rollers is movable between an operating position and a spaced position so as to allow removal of the box (or the side wall of the box) at the exit.

Preferably, these guide means are arranged in a fixed position with respect to the gripper (and the rotatable support).

Preferably, these guide means are arranged close to the end of the blank feeding path; namely, these guide means (said pair of rollers) are positioned relative to the feeding means so that the blank is fed by the feeding means towards the guide means.

For example, these guide means comprise a plurality of rollers and/or deviating members (for example blades).

It should be noted that it is envisaged that said guide means should also be adjustable positionwise in order to perform a change in format.

Preferably, the machine comprise a retaining member (for example a suction cup) suitable for retaining a bottom wall of the box without interfering with an edge thereof. This retaining member is connected to the folding station (or interacts with it) so as to arrange said bottom wall in a predetermined position, in which the edge of said wall is surrounded by the blank folded so as to define the side wall of the box.

Preferably, said retaining member is connected to the rotating support. Preferably, said retaining member is coaxial with the folding axis; preferably, said retaining member is coaxial with the axis of rotation of the rotating support.

Preferably, at least one part of the gripper is movable between a first operating position, where it grips the blank, and second operating position, where it does not interfere with the blank.

Preferably, said at least one part of the gripper is movably connected to the rotating support, so as to be displaced between said operating positions, while remaining associated with the rotating support.

Preferably, said at least one part of the gripper is rotationally movable in a radial plane with respect to the folding axis (or axis of rotation of the rotating support), so as to move between said operating positions.

Preferably, it is also envisaged providing a pre-folding station arranged upstream of the folding station so as to impart to the blank a partial curvature, which is smaller than the curvature provided by the folding station, so as to assist gripping of the front end of the blank by the gripper. Preferably, the machine also comprises a clinching station, arranged upstream of the folding station, so as to perform folding of the blank onto itself about a folding line parallel to the feeding path of the feeding means, thereby providing the blank with a superimposed (multilayer) structure having a greater rigidity than the initial blank.

The clinching station may be preceded by a further gluing station for introducing at least one layer of glue between two surface portions of the blank intended to face each other following superimposition performed in the clinching station. This glue is preferably a slow setting glue so that, during a following curving step in the folding station, the two superimposed panels of the blank may slide relative to each other (owing to the different diameter of curvature) despite the introduction of glue in between.

The method according to the present invention is characterized by preparing a blank such that the joining line of the opposite edges of the blank, following curving of the blank, is arranged along a trajectory which is at least partly helical.

In particular, the curving of the blank is performed along a curved, preferably circular, trajectory by means of movement of one of the said opposite edges of the blank along the curved trajectory.

This is advantageously achieved without any step for winding the blank onto a central mounting spindle.

Preferably, the blank has two panels arranged alongside each other and, prior to curving, undergoes clinching so as to superimpose the two panels at least partly on each other, obtaining a multilayer structure having a greater rigidity than the original blank.

The clinching step is preferably preceded by a step for applying a slow setting glue (with a setting time for example of 3 minutes, preferably at least 2 minutes) onto parts of the surface of the two panels which are intended to come into contact with each other. The use of this glue allows fixing, after a predetermined time period has lapsed, of the two panels without however precluding a sufficient degree of relative sliding of the two panels during curving.

Preferably, superimposition of the two panels is performed on a part of the surface thereof, each panel therefore having at least its one exposed end portion which is subject to application of a fast setting glue for fixing together the opposite edges of the blank once curving has been completed.

Preferably, folding along the curved trajectory is preceded by a step involving pre-folding of the superimposed panels so as to impart a partial curvature to the panels, in order to assist gripping thereof by the gripper for performing curving of the blank. Preferably, the blank has a substantially parallelogram configuration so as to form the said helical joining line and assist lateral gripping of a front vertex of the blank by the gripper.

Thus, the invention also provides a method for erecting a box by folding a paper blank having peculiar features.

Regarding said blank, the following is observed.

In particular, the blank is defined by a panel made of flexible material, preferably paper material, which can be folded along a curved trajectory so as to define a side wall of a round box and having a first edge and second edge situated opposite each other and a third edge and fourth edge also situated opposite each other and transverse to the first edge and second edge. The first edge and second edge have respective outer profiles which complement each other so as to make end-to-end contact with each other defining a joining line.

The outer profiles of the first edge and second edge are formed so that the joining line defined by them is at least partly helical.

Preferably, at least the third edge, and even more preferably also the fourth edge, is straight so as to assume, following folding along said curved trajectory, the configuration of a closed line lying in a plane, preferably a circumference.

Preferably, in the blank, the helical form of the joining line is obtained by providing, at least a first section of each first and second edge, with a straight form inclined relative to the third edge.

Preferably, in an embodiment of the blank according to the invention, each first edge and second edge also has at least one second straight section oriented perpendicularly with respect to the third edge so that the joining line has at least one corresponding straight section arranged along a generatrix of the side wall of the round box. These second sections have the function of providing a locating abutment when the first edge and second edge are moved towards each other, preventing undesirable sliding along the first inclined sections. Moreover, the cooperation between the first section and second section of each first edge and second edge defines a profile which extends along a broken line, and these broken-line profiles complement each other and define in a specific manner the correct contact position of the first edge and second edge.

In particular, preferably, each one of said first and second edge is (completely) defined by said first straight section inclined (of a predetermined first angle) with respect to the third edge and said second straight section oriented perpendicularly with respect to the third edge. In a preferred embodiment, the blank comprises two panels which are arranged alongside each other along the respective third edge and can be folded over onto each other so as to obtain a superimposed configuration suitable for providing the side wall of the box with a multilayer structure. Regarding said second panel, preferably, each one of said first and second edge (of the second panel) is (completely) defined by said first straight section inclined (of a predetermined second angle, which is preferably different from said first predetermined angle) with respect to the third edge and said second straight section oriented perpendicularly with respect to the third edge.

Preferably, the first and second edge of the second panel are inclined with respect to the corresponding third edge by an angle which is different from the angle of inclination of the first and second edge of the first panel with respect to the corresponding third edge.

This feature allows the end portions of the first and second panel to match precisely, although the two panels are superposed and thus positioned at different distances from a folding axis (i.e. the axis around which the blank is folded).

Brief description of drawings

The technical features of the invention, in accordance with the abovementioned object, may be clearly determined from the contents of the claims provided below and the advantages thereof will emerge more clearly from the detailed description which follows, with reference to the accompanying drawings which illustrate a purely exemplary and non- limiting embodiment thereof, where:

- Figures 1A, 2A and 3A show three simplified embodiments of a blank used in a method according to the present invention;

- Figures 1 B, 2B and 3B show three side walls for round boxes obtained, respectively, from the blanks according to Figures 1A, 2A and 3A;

- Figure 4 is a plan view of a blank used in a method according to the present invention in accordance with a fourth embodiment;

- Figures 5 to 8 show the blank according to Figure 4 in different configurations assumed during successive steps of a folding method according to the present invention:

- Figure 9 shows a machine for making round boxes according to the present invention;

- Figure 10 shows a detail of the machine according to Figure 9;

- Figures 1 1 and 12 show a front view of the machine part shown in Figure 10, during two successive operating instants;

- Figure 13 shows a front view of the machine part shown in Figure 10, in an operating configuration different from that of Figures 1 1 and 12;

- Figure 14 shows a detail of the machine according to Figure 9, in a cross-sectional side view.

Detailed description of preferred embodiments of the invention

In accordance with the accompanying figures, 1 denotes a blank for making a round box, used in a method according to the present invention.

The blank 1 consists of a flat body, preferably made of paper and having a mainly elongate surface.

As can be seen in Figures 1A, 2A, 3A, the blank 1 comprises at least one panel 2 having advantageously the form of a parallelogram with a first edge and second edge 3, 4 situated opposite each other and a third edge and fourth edge 5, 6 also situated opposite to each other and transverse to the first edge and second edge 3, 4.

The panel 2 can be folded along a curved trajectory so as to define a side wall "P" of a round box.

Figures 1 B, 2B, 3B show the blank 1 in the folded configuration defining the said side wall "P".

The first and second edges 3, 4 have outer profiles complementing each other so that, once the blank 1 has been folded, these edges 3, 4 make end-to-end contact with each other along their entire length, in particular along a continuous joining line.

Advantageously, the outer profiles of the first edge and second edge 3, 4 are formed so that, following folding along the said curved trajectory, they may be brought into end-to-end contact with each other along a joining line "G" which is substantially helical, in other words a joining line which extends spirally along the axis of extension of the side wall "P".

This enables a stronger joint to be obtained, not subject to the "pear-like" deformation which instead occurs in the case of joints arranged along a generatrix of the cylindrical side wall "P".

Preferably, at least the third edge 5 is straight. This allows the third edge 5 to assume, following folding of the blank 1 along the said curved trajectory, the configuration of a closed line lying in a plane, in particular a circumference, suitable for defining a base "B" of the side wall "P".

Preferably, as shown in the embodiments of Figures 1A, 2A, 3A, the fourth edge 6 is also straight and is parallel to the third edge 5.

In the embodiments shown in Figures 1A, 2A, 3A, the first edge and second edge 3, 4 have at least one first straight section 3a, 4a, inclined at a predetermined angle "a" relative to the third edge 5 so as to define, following folding along said curved trajectory, the aforementioned helical joining line "G".

Preferably, the first edge and second edge 3, 4 are parallel.

In the first embodiment of the blank 1 , shown in Figure 1A, the winding angle of the joining line "G" about the axis of extension (symmetry) of the side wall "P", following folding of the blank 1 along said curved trajectory, is less than 360°. In fact, the length of the third edge and fourth edge 3, 4 is equal to the length of the circumference (erect line) of the base "B" of the side wall "P", while the projection "H" of the first edge 3 on the third edge 5 is smaller than this length and therefore only covers a section of the said circumference.

In the second embodiment of the blank 1 , shown in Figure 2A, the winding angle of the joining line "G", following folding of the blank 1 along said curved trajectory, is equal to 360°. In fact, in this case the length of the projection of the first edge 3 on the third edge 5 is equal to the length of the third edge 3 and therefore the joining line "G" (defined by the first edge 3) covers the entire circumference of the base "B".

In the third embodiment of the blank 1 , shown in Figure 3A, the winding angle of the joining line "G", following folding of the blank 1 along said curved trajectory, is greater than 360°. In fact, in this case the length of the projection of the first edge 3 on the third edge 5 exceeds the length of the third edge 3, and therefore the joining line "G" (defined by the first edge 3) has an extension greater than the circumference of the base "B".

Figure 4 shows a detailed view of a further embodiment of the blank 1 . In this embodiment the blank 1 comprises two panels 2, 2', each of which in accordance with that described and illustrated above.

Therefore, the two panels 2, 2' have a form substantially of a parallelogram and, in the embodiment shown in Figures 4-8, the panels correspond to the embodiment shown in Figure 1A and therefore are suitable for forming a joining line "G" with a winding angle smaller than

360°.

In greater detail, the panels 2, 2' have a main direction of extension parallel to the third edge and fourth edge 5, 5', 6, 6' and face each other along the respective third edge 5, 5'.

Preferably, the panels 2, 2' are connected together along a section of the third edge 5, 5', while they are instead not connected along the remainder of the third edge 5, 5'. This section of the third edge 5, 5' therefore defines a connecting portion 7 of the panels 2, 2'.

Preferably, the two panels 2, 2' are connected together along an end portion of the respective third edge 5, 5' and the third edges 5, 5' are arranged alongside each other over most of their length.

Preferably, said two panels are connected together also along a second section of the third edge defining a connecting portion of the panels and are instead not connected over the remainder of the third edge.

Preferably, the two panels and the connecting portion are formed as one piece by means of cutting of a sheet of flexible, preferably paper material. For reasons which will be clarified below, it is preferable that the two panels 2, 2' are arranged staggered relative to each other along the third edge 5, 5', in particular staggered by an amount such as to define two steps 8, 8' (or "noses") positioned opposite each other in the main direction of extension of the panels 2, 2'.

Preferably, moreover, in the embodiment shown in Figures 4-8, the first edge and second edge 3, 4 of each panel 2, 2' also have at least one second straight section 3b, 3b', 4b, 4b' oriented perpendicularly with respect to the third straight edge 5, 5' and adjacent thereto.

In other words the first edge and second edge 5, 5' of each panel 2, 2' assume an outer profile defined by a broken line.

As shown in Figures 5 and 6, the two panels 2, 2' can be folded onto each other (by means of a folding or "clinching" operation) about the respective third edges 5, 5' arranged alongside each other, so as to obtain a superimposed configuration suitable for providing the side wall "P" of the box with a multilayer structure. In this way, a first panel defines the inner face of the side wall "P" of the box, while the other panel defines the outer face of the side wall "P".

Since the panels 2, 2' are staggered along the third edge 5, 5', in the superimposed configuration, each panel 2, 2' covers only partially the other panel 2, 2', leaving an end portion 9, 9' of the other panel 2, 2' exposed.

The exposed end portion 9 of a panel 2 can be associated by means of superimposition on a corresponding, opposite, exposed, end portion 9' of the other panel 2' following folding of the panels 2, 2' along the curved trajectory (Figures 7 and 8).

By means of suitable gluing of the two exposed end portions 9, 9' the blank 1 can be fixed in the folded configuration defining the side wall "P" of the box in a multilayer configuration.

Moreover, the aforementioned joining line "G", following folding of the blank 1 along the said curved trajectory, has at least one straight section "R" defined by joining together of the said second straight sections 3b, 3b'; 4b, 4b' of the first edge and second edge 3, 3'; 4, 4'.

This straight section "R" therefore defined by the aforementioned steps 8, 8' of the panels 2, 2' has the dual function of strengthening the ends of the panels 2, 2' and ensuring frontal locking abutment between the ends of the panels 2, 2' during folding of the blank along the curved trajectory. This allows the mutual position of the first edge and second edge 3, 3'; 4, 4' to be precisely determined when sealing them in order to obtain the side wall "P", preventing damaging sliding movements which could arise if the second straight sections 3b, 3b'; 4b, 4b' were not present.

More precisely, moreover, in the multilayer configuration shown in Figures 4-8 the blank 1 gives rise to two joining lines "G", one directed towards the outer face of the side wall "P" and one directed towards the inner face of the side wall "P". The two joining lines "G", which can be seen in Figure 8, are angularly staggered about the axis of extension of the side wall "P".

As can be seen in Figure 4, in the non-superimposed configuration of the panels 2, 2', the first inclined sections 3a, 4a of a panel 2 are inclined in the opposite direction to the corresponding first inclined sections 3a', 4a' of the other panel 2' so that, on one side of the blank 1 , the first inclined sections 3a, 3a' converge, while, on the other side, they diverge. This provides the blank 1 with an "arrow-like" configuration. As a result, by folding over one panel 2 onto the other panel 2', the first inclined sections 3a, 3a' arranged on the same side of the blank 1 are parallel or substantially parallel to each other.

In particular, it is possible that the angle "a" formed between the first inclined sections 3a, 4a of a first panel 2 (which, as described above, are parallel to each other) and the third edge 5 of the first panel 2 is different from the angle "α'" formed by the first inclined sections 3a', 4a' of the second panel 2 with respect to the third straight edge 5" of the second panel 2'.

In the embodiment shown in Figures 4-8, moreover, the second straight sections 3b, 4b of a panel 2 (which have the same length, since they must come into contact against each other) have a different length compared to the second straight sections 3b', 4b' of the other panel 2'.

As regards the curvature guide means 104, the following should be noted. Preferably the guide means 104 comprise a pair of rollers configured to keep the blank 1 slidably inserted therein.

In particular, the guide means 104 comprise an inner roller 41 and an outer roller 42; these rollers are arranged alongside each other, defining a slit inside which the blank 1 , inserted between the two rollers, is slidable. Preferably, the inner roller 41 is movable between an operating position and a spaced position so as to allow removal of the box (or the side wall of the box) at the exit.

Preferably, the inner roller 41 is connected to the fixed frame 1 12 so as to be movable along a trajectory which performs an axial displacement (along the axis of the said cylinder) and a radial displacement (away from the other roller); the inner roller 41 is connected to the fixed frame 1 12 by means of a hinged quadrilateral (not shown, of the type known per se). It should be noted that, alternatively or in addition, it is envisaged that the outer roller 42 is movable.

The rollers 41 and 42 remain stationary, while the gripper 1 10 rotates, during folding of the blank 1 for formation of the side wall of the box. Preferably, the guide means 1 14 also comprise a blade 43 with the function of a deviator, or for providing a constraint for the position of the blank 1 during folding thereof.

Preferably, the blade 43 is preferably arranged tangentially with respect to a cylindrical surface having as its axis the folding axis X (about which the gripper rotates) and as radius the distance between the gripper 1 10 and said axis.

The round box to be made comprises, in addition to the (cylindrical) side wall P formed by folding the blank 1 , also a bottom wall B (also called "base" of the box).

Preferably, the side wall is cylindrical and the bottom wall is a circular disc. In this respect, it should be noted that, preferably, the machine 100 comprises a retaining member 51 (for example a suction cup) suitable for retaining the bottom wall of the box in the folding station, without interfering with an edge thereof.

This retaining member 51 is connected to the folding station 108 (or interacts with it) so as to arrange said bottom wall B in a predetermined position, so that the blank 1 is folded around said bottom wall B.

Preferably, the retaining member 51 is connected to the rotatable or rotating support 109; moreover, the retaining member 51 is coaxial with the folding axis X, or the axis of rotation of the rotating support 109.

As regard the gripper 1 10, the following should be noted.

The gripper 1 10 comprises two parts, a first part 61 and a second part 62, which are movable relative to each other between a position close to each other, where they press against the blank 1 arranged in between so as to grip and retain it, and a spaced position, where they allow the blank 1 to enter into and come out of the space present between the two said parts 61 and 62.

Preferably, at least one of said two parts 61 and 62 of the gripper 1 10 is movable between a first operating position, where it grips the blank, and a second operating position, where it does not interfere with the blank. In the example shown, the first part 61 of the gripper 1 10 is movable relative to the second part 62 and to the rotating support 109, while the second part 62 of the gripper 1 10 is in a fixed position relative to the rotating support 109.

In the example shown, the first part 61 of the gripper 1 10 is arranged internally (i.e. is in a position close to the folding axis X) and the second part 62 is arranged externally (i.e. is in a position remote from the folding axis X), with respect to the wall P formed by folding of the blank 1 .

Preferably, the first part 61 of the gripper 1 10 is movably connected to the rotating support 109, so as to be displaced between said operating positions, while remaining associated with the rotating support 109.

Preferably, the first part 61 of the gripper 1 10 is rotationally movable in a radial plane passing through the folding axis X (namely the axis of rotation of the rotating support), so as to move between said operating positions. This allows the formed box to be extracted in a particularly easy manner. The first part 61 of the gripper 1 10 is pivotably mounted on a bracket 63 of the rotating support 109 at a pivot point 64.

The movement of the first part 61 of the gripper 1 10 relative to the rotating support 109 is performed by an actuator (not shown), preferably of the single-acting type, preferably in cooperation with a spring 65.

It should be noted that the rotating support 109 and the gripper 1 10 form part of an assembly 66 rotating about the folding axis X.

Preferably, the rotating assembly 66 is connected to an electric motor (not shown, of the type known per se) which is preferably coaxial with the folding axis X.

The present invention also provides a procedure (or a method) for making round boxes (in general) and in particular for forming the side wall of a round box.

The method of making round boxes, using a blank of the type described above, therefore essentially comprises a step of folding of the blank (or the panels 2, 2') along a curved trajectory (preferably a circumference), as can be seen in Figure 7, until the first edge and second edge 3, 4; 3', 4' of each panel 2, 2' make end-to-end contact with each other (Figure 8), and then joining together said first edge and second edge 3, 4; 3', 4', obtaining a round side wall "P" of a box.

This step of folding along the curved trajectory is preceded by a step of folding over the two panels 2, 2' onto each other about the third edges 5, 5' so as to obtain a superimposed configuration suitable for providing the side wall "P" of the box with a multilayer structure.

The step of folding over onto each other the two panels 2, 2' about the third edges 5, 5' results in a superimposed arrangement of the panels 2, 2' along their respective contact surfaces, except for the aforementioned exposed end portions 9, 9'.

Preferably the said contact surfaces intended to be superimposed are lined with a slow setting glue (with a setting time for example of about 3 minutes, preferably at least 1 minute) suitable for allowing relative sliding of the two panels 2, 2' during folding along said curved trajectory. This folding operation in fact arranges the two panels 2, 2' along two curved paths having a different distance from a centre of instantaneous rotation and this inevitably results in the relative sliding of the two panels 2, 2' along their mutual contact surface.

This sliding action is moreover favoured precisely by the fact that the two panels 2, 2' are totally separate from each other apart from the small connecting portion 7.

With reference to the exposed end portions 9, 9', which are not superimposed, they are preferably lined with a fast setting or normal setting glue (with a setting time for example of 5 seconds, preferably 2 to 10 seconds).

In a preferred embodiment of the method, the step of applying the glue onto the exposed end portions is performed after the step of folding over of the panels onto each other and therefore after application of the slow setting glue. Advantageously, the particular form of the panels 2, 2' allows them to be folded about the curved trajectory simply by gripping a front end of the blank 1 with the two panels 2, 2' which are already superimposed.

Continuation of the folding action may be assisted by a series of rollers which produce a curved or circular path and terminate in the mutually superimposed arrangement of the exposed end portions 9, 9'.

Advantageously, this operation may be performed without the use of a central mounting spindle and simply requires a system for supporting a gripper arranged on the side of the curved trajectory followed by the blank. Owing to the particular "arrow-like" form of the blank, in fact, following folding over of one panel onto the other one, a substantially parallelogram configuration of the blank may be obtained, this being able to be easily gripped at a vertex of the parallelogram defining an acute angle. This vertex, in fact, also where it is defined by the said second straight section 3b, 3b'; 4b, 4b', forms a "tip" of the parallelogram which is particularly suitable for griping by means of special gripping systems which will be described below.

A machine for making round boxes according to the present invention, in accordance with Figures 9-13 and preferably for implementing the method described above, is now described.

The machine, denoted overall by 100, comprises means 101 for feeding a blank 1 along a feeding path "A".

The feeding means 101 comprise preferably one or more conveyor belts 102 arranged in succession with each other.

The feeding means 101 define a horizontal conveying surface 102a on which a succession of blanks 1 are conveyed.

The embodiment of the machine 100 shown in Figures 9-13 is specifically designed to fold blanks 1 comprising two panels 2, 2' of the type shown in Figure 4. However, it may also be used for blanks 1 of the type shown in Figures 1A-3A.

In greater detail, as can be seen in Figure 9, a clinching station 103 is arranged along the feeding path "A", said station being suitable for performing folding of the blank 1 onto itself about the said third edges 5, 5', namely about a folding line parallel to the feeding path "P" of the feeding means 101 .

This clinching station 103 comprises preferably a twisted belt 104 defined by a succession of rollers. These rollers are gradually inclined from an initial orientation, parallel to and alongside the conveying surface 102a defined by the feeding means 101 , into a final orientation, parallel to and arranged over said conveying surface 102a. During the transition from the initial orientation into the final orientation, rotation through 180° of one panel 2' onto the other panel 2 occurs, therefore resulting in a "clinched" arrangement in accordance with Figures 5 and 6.

A first gluing station 105 is arranged downstream of the clinching station, relative to the feeding path "A", and is designed to release onto the blank 1 a layer of glue at least along one of the aforementioned exposed end portions 9, 9' of the blank 1 .

The first gluing station is configured to release the said layer of glue onto the blank 1 in a direction transverse and not perpendicular to the feeding path "A", in particular along a direction parallel to the first edge and second edge 3, 3'; 4, 4' of the blank 1 .

Moreover, the first gluing station 105 is configured to coordinate the glue releasing action with feeding of the blank 1 along the feeding path "A". In order to achieve this, the first gluing station 105 comprises a glue dispensing arm 106 arranged above the conveying surface 102a and movable along the feeding path "A" so as to assume the same speed of feeding of the blank 1 during release of the glue onto the blank 1 .

As can be seen in Figure 10, the dispensing arm 106 is mounted so as to project from a longitudinal guide 107 arranged alongside the conveying surface 102a and aligned along the feeding path "A". The dispensing arm 106 can also be inclined with respect to the guide 107 so to vary its inclination with respect to the feeding path "A". A folding station 108 is arranged downstream of the first gluing station 105 and is configured so as to perform folding of the blank 1 along a curved trajectory so as to bring opposite edges 3, 3'; 4, 4' of the blank 1 (in particular the first and second edges) into end-to-end contact with each other, thus defining the said joining line "G".

Advantageously, the first gluing station 105 is configured so as to release the layer of glue onto the blank 1 along a direction defining, once the blank 1 has been folded, an at least partly helical trajectory.

In other words, the first gluing station 105 distributes the glue along a line, which is preferably straight and even more preferably parallel to the first and/or second edge 3, 3'; 4, 4' of the blank 1 , such as to define a trajectory which is at least partly helical, once the blank 1 has been folded, substantially coinciding with the joining line "G".

Therefore, the glue released by the first gluing station 105 has the aim of fixing the blank 1 in a folded cylindrical configuration by means of sealing along, or opposite, the joining line "G". The glue deposited by the first gluing station 105 is in fact intended to connect together the first and second edges 3, 3; 4, 4' and, more specifically, exposed end portions 9, 9' (at least one of the latter in fact forms the portion of the blank 1 intended to receive the glue from the first gluing station 105).

In greater detail, the folding station 108 comprises a rotatable support 109 having an axis of rotation "X" parallel to the conveying surface 102a and preferably perpendicular to the feeding path "A", and therefore horizontal, and preferably defined by a rotating disc lying in a vertical plane.

A gripper 1 10 is mounted on the rotatable support 109 and is designed to grip a front end portion of the blank 1 (namely that portion directed in the feeding direction) and movable along a circular trajectory so as to impart to the aforementioned end portion of the blank 1 the circular folding trajectory.

The gripper 1 10 comprises a pair of teeth, at least one of which is movable towards and away from each other so as to grip stably the said end portion of the blank 1 .

The gripper 100 therefore grips the blank 1 and pulls it along the curved trajectory, performing permanent curving thereof.

Advantageously, the gripper 1 10 is mounted on the rotatable support adjustably so as to vary the distance of the gripper 100 from the axis of rotation "X" of the rotatable support.

In order to achieve this, the gripper 1 10 is slidably inserted along a radial groove 1 1 1 , namely extending along a direction passing through the axis of rotation "X", and the position of the gripper 1 10 along the groove 1 1 1 is adjustable by means of adjusting means, not shown (for example a screw/female thread actuating system.

As a consequence, the variation in position of the gripper 1 10 along the groove 1 1 1 produces different radii of curvature of the curved trajectory and therefore different diameters of the side wall "P" of the resultant box. By way of example, Figures 1 1 and 12 show two successive instants of curving of the blank 1 which takes place in the folding station 108, while Figure 13 shows an instant of an operation for curving the blank 1 along a trajectory having a diameter greater than the preceding diameter, obtained by means of movement of the gripper 1 10 away from the axis of rotation "X".

Preferably, moreover, the folding station comprises a fixed frame 1 12 and the rotatable support 109 is mounted adjustably on the fixed frame 1 12 so as to vary the distance of the axis of rotation "X" of the rotatable support

109 from the conveying surface 102a.

This adjustment is obtained by providing a slotted upright 1 13 on the fixed frame and connecting in an adjustable manner the rotatable support 109 on the slotted upright 1 13. The position of the axis of rotation "X" of the rotatable support 109 is therefore adjustable along the slot of the upright 1 13 and this has the function in particular of adjusting the position of the rotatable support 109 depending on the position assumed by the gripper

1 10 along the slot 1 1 1 . In fact, it is preferable that, during operation of the machine, the gripper 1 10 should follow a trajectory which is tangential or in any case very close to the conveying surface 102a and therefore, if the gripper 1 10 is moved towards the axis of rotation "X", the latter is moved towards the conveying surface 102a so as to move the trajectory of the gripper 1 10 closer to the conveying surface 102a.

In particular, Figure 13 shows the rotatable support 109 in a fixing position removed from the conveying surface 102a so as to compensate for the greater diameter of the trajectory followed by the gripper 1 10.

As can be seen in Figures 1 1 -13, the folding station 108 also comprises guide means 1 14 which are arranged on the outside of the curved trajectory (identified by the gripper 1 10) so as to favour curving of the blank 1 during feeding along the curved trajectory.

These guide means 1 14 comprise a succession of rollers and/or deviating members suitable for defining a succession of supporting points for the blank 1 along the curved trajectory.

Preferably, these guide means 1 14 are also adjustable so as to adapt to the different configurations assumed by the gripper 1 10 and by the rotatable support 109.

In order to assist gripping of the end portion of the blank 1 by the gripper 1 10, a pre-folding station 1 15 is arranged upstream of the folding station 108 and preferably downstream of the clinching station 103, along the feeding path "A", said station being designed to impart to the blank 1 a partial curvature smaller than the curvature provided by the folding station 108. This partial curvature causes raising of the front end portion of the blank 1 (which is partially curved with its concavity directed upwards, i.e. so that it rests on the rear side), and this end can therefore be easily gripped by the gripper 1 10.

In the embodiment shown in Figure 9, the pre-folding station comprises a train of rollers (at least three, one of which is arranged in between the other two and facing them) defining a curved through-trajectory for the blank 1 , with in any case a diameter greater than the curved trajectory imparted by the folding station 108.

Preferably, moreover, the feeding path "A" has, arranged along it, upstream of the clinching station 103 a second gluing station (not shown) for introducing at least one layer of glue between two surface portions of the blank intended to face each other following superimposition performed in the clinching station 103.

It should be noted that, preferably the method according to the invention comprises the following steps:

- supplying at least one paper or cardboard disc, suitable for defining a bottom wall B of the box, to the retaining member 51 ;

- retaining said disc, without interfering with a perimetral edge thereof (by means of the retaining member 51 ), in the folding station 108, in a predetermined position where the edge of said disc is operationally surrounded by the blank 1 folded so as to define the side wall P of the box. It should be noted that the method according to the invention envisages a step of providing a gripper 1 10 operationally active on an edge of the blank and movable along said curved trajectory.

Moreover, the method according to the invention envisages a step of providing guide means 1 14 arranged in a fixed position with respect to the movement of the gripper 1 10 and operationally interacting with the blank 1 during folding.

Moreover, the method according to the invention envisages a step of displacing, following the fixing step (or the step for forming the side wall P of the box by joining together the edges of the blank 1 ), at least one part 61 of the gripper 1 10 from a first configuration, where it is operationally active on the blank 1 , to a second configuration, where it is arranged in position such as not interfere with the blank 1 , in order to allow movement of the box (or the side wall P of the box) leaving the machine.

Moreover, the method according to the invention envisages a step of displacing, following the fixing step (or the step for forming the side wall P of the box by joining together the edges of the blank 1 ), at least one part of the guide means 1 14 (preferably the inner roller 41 ) from a first configuration, where it is operationally active on the blank 1 , into a second configuration, where it is arranged in position such as not interfere with the blank 1 , so as to allow movement of the box (or the side wall P of the box) leaving the machine.

The invention thus conceived may obviously be implemented on an industrial level; moreover it may also be subject to numerous modifications and variations all falling within the scope of the inventive idea; all the details may be replaced moreover by technically equivalent elements. The invention therefore achieves the predefined objects, overcoming the problems associated with the prior art.

The machine according to the invention operates without using a central mounting spindle for the blank. The provision of a folding system based on the gripper mounted on a rotatable support, in fact, is able to perform permanent curving of the blank without the need for continuous internal supporting of the blank, namely inside the curved trajectory. This results in a logistical simplification since it is no longer required to take into account the need for storing spindles and tubes from which the sections for forming the boxes are cut.

Moreover, owing to the possibility of adjusting the position of the gripper on the rotatable support, it is possible to vary continuously the diameter of curvature of the blank, achieving a high degree of versatility in terms of the formats which can be produced.

Owing to the use of the specific blank described, it is possible to obtain an optimum cylindrical form of the cylindrical side wall once curving has been completed, together with a high manufacturing precision in keeping with tolerances.

Claims

1 . Machine for making round paper or cardboard boxes, comprising:

- means (101 ) for feeding a blank (1 ) along a feeding path (A);

- a folding station (108) arranged along said feeding path (A) and configured to perform folding of the blank (1 ) along a curved trajectory so as to bring opposite edges (3, 3'; 4, 4') of said blank (1 ) into end-to-end contact with each other, thus defining a joining line (G);

- at least one gluing station (105) for releasing onto said blank (1 ) a layer of glue for sealing said joining line (G);

characterized in that said first gluing station (105) is configured to release said layer of glue onto the blank (1 ) along a direction defining, once the blank (1 ) has been folded, an at least partly helical trajectory.

2. Machine according to claim 1 , wherein:

said folding station (108) is configured to perform folding of the blank (1 ) along a circular trajectory around a folding axis, and wherein

said first gluing station (105) is configured to release said layer of glue onto the blank (1 ) along a segment inclined with respect to said folding axis (X).

3. Machine according to claim 2, wherein said first gluing station (105) comprises a glue dispenser (106) arranged above said feeding means (101 ) and movable along said feeding path (A) so as to assume the same speed of feeding of the blank (1 ) during release of the glue onto the blank

(1 )-

4. Machine according to any one of the preceding claims, wherein said folding station (108) comprises a gripper (1 10) designed to grip an end portion of a blank (1 ) and movable along a circular trajectory so as to impart to said end portion of the blank (1 ) said circular trajectory.

5. Machine according to claim 4, wherein said folding station (108) comprises a rotatable support (109) on which said gripper (1 10) is mounted, said rotatable support (109) having an axis of rotation (X) parallel to a conveying surface (102a) defined by said feeding means (101 ) and wherein said gripper (1 10) is mounted on said rotatable support (109) in an adjustable manner so as to vary a distance of the gripper (1 10) from said axis of rotation (X).

6. Machine according to claim 5, wherein said folding station (108) comprises a fixed frame (1 12) and wherein said rotatable support (109) is mounted in an adjustable manner on the fixed frame (1 12) so as to vary a distance of the said axis of rotation (X) from the conveying surface (102a).

7. Machine according to any one of the preceding claims 4 to 6, wherein said folding station (108) also comprises guide means (1 14) arranged on the outside of said circular trajectory defined by the gripper (1 10) so as to assist curving of the blank (1 ) during feeding along said circular trajectory.

8. Machine according to any one of the preceding claims, comprising a retaining member suitable for retaining a bottom wall of the box without interfering with an edge thereof and connected to the folding station so as to arrange said bottom wall in a predetermined position where the edge of said wall is surrounded by the blank folded so as to define the side wall of the box.

9. Machine according to any one of the preceding claims, also comprising a pre-folding station (1 15) arranged upstream of the folding station (108) and designed to impart to said blank (1 ) a partial curvature smaller than the curvature provided by said folding station (108).

10. Machine according to any one of the preceding claims, also comprising a clinching station (103) arranged upstream of the folding station (108) and suitable for performing folding of the blank (1 ) onto itself about a folding line parallel to the feeding path (A) of the feeding means (101 ).

1 1 . Machine according to claim 10, comprising moreover a second gluing station arranged upstream of the clinching station (103) for introducing at least one layer of glue between two surface portions of the blank (1 ) intended to face each other following superimposition performed in the clinching station (103).

12. Method for making round boxes, comprising the following steps:

- preparing a blank (1 ) comprising at least one panel (2, 2') having a first edge and second edge (3, 4; 3', 4') situated opposite each other and a third edge and fourth edge (5, 6, 5', 6') also situated opposite each other and transverse to said first edge and second edge (3, 4; 3', 4'), said first edge and second edge (3, 4; 3', 4') having respective outer profiles complementing each other and formed so that they can be brought into end-to-end contact with each other along a joining line (G) which is at least partly helical following folding of said panel (2, 2') along a curved trajectory;

- folding said at least one panel (2, 2') along a curved trajectory so as to bring said first edge and second edge (3, 4; 3', 4') into end-to-end contact with each other in order to define said joining line (G) which is at least partly helical;

- fixing together said first edge and second edge (3, 4; 3', 4'), obtaining a round side wall (P) of a box.

13. Method according to claim 12, wherein said step of folding said at least one panel (2, 2') along a curved trajectory is performed by moving one of said first or second edges (3, 4; 3', 4') along a circular trajectory.

14. Method according to claim 12 or claim 13, wherein said step of preparing the blank is performed by preparing a blank comprising two of said panels (2, 2') which are arranged alongside each other along the respective third edge (5, 5') and can be folded onto each other so as to obtain a superimposed configuration suitable for providing said side wall (P) of the box with a multilayer structure and wherein the step of folding said at least one panel (2, 2') along the curved trajectory is preceded by a step of clinching one of said panels (2') onto the other panel (2) about said third edges (5, 5').

15. Method according to claim 14, wherein said step of clinching onto each other said two panels (2, 2') about said third edges (5, 5') results in mutual superimposition of said panels (2, 2') along respective mutual contact surfaces and wherein said step of clinching about said third edges (5, 5') is preceded by a step for applying, on at least a part of said contact surface of at least one of the panels (2, 2'), a slow setting glue suitable for allowing relative sliding of the two panels (2, 2') during folding along said curved trajectory.

16. Method according to claim 15, wherein said step of clinching about said third edges (5, 5') is performed so as to superimpose on each other only partly said panels (2, 2;) without superimposing at least one exposed end portion (9, 9') of each panel (2, 2') and wherein said step of clinching about said third edges (5, 5') is followed by a step for applying a fast setting glue onto at least one of said exposed end portions (9, 9').

17. Method according to any one of the preceding claims 14 to 16, wherein, between the step of clinching about said third edges (5, 5') and the step of folding along said curved trajectory, a step for pre-folding said superimposed panels (2, 2') is inserted so as to impart a partial curvature to said superimposed panels (2, 2').

18. Method according to any one of the preceding claims 12 to 17, wherein said blank (1 ) has a substantially parallelogram form and wherein said step of folding said at least one panel (2, 2') along the curved trajectory is performed by gripping a vertex of said parallelogram, defining an acute angle, by means of a gripper (1 10) movable along said curved trajectory.

19. Method according to any one of the preceding claims 12 to 18, comprising the following steps:

- supplying a paper or cardboard disc, suitable for defining a bottom wall of the box, to a retaining member;

- retaining said disc, without interfering with a perimetral edge thereof, in the folding station, in a predetermined position where said perimetral edge is operationally surrounded by the blank folded so as to define the side wall of the box.

20. Method according to any one of the preceding claims 12 to 19, comprising the following steps:

- providing a gripper (1 10) operationally active on an edge of the blank and movable along said curved trajectory;

- providing guide means arranged in a fixed position with respect to the movement of the gripper and operationally interacting with the blank during folding;

- displacing, following the fixing step, at least one part of the gripper (1 10) and/or at least one part of the guide means from a first configuration, where they are operationally active on the blank, into a second configuration, where they are arranged in a position where they do not interfere with the blank, so as to allow movement of the box leaving the machine.