A folding unit for folding a tuck-in closing flap of a head of boxes in tubular configuration

Abstract

The folding unit (100) carries out the folding of the tuck-in closing flap (L) of a head (T) of boxes (A) in a tubular configuration which are fed along an infeed direction (V) and positioned in a pause position (P).

Description

[0001] A FOLDING UNIT FOR FOLDING A TUCK-IN CLOSING FLAP OF A HEAD OF BOXES IN TUBULAR CONFIGURATION

[0002] DESCRIPTION OF THE INVENTION

[0003] FIELD OF THE INVENTION

[0004] The present invention relates to the technical sector relating to the packaging of products internally of boxes.

[0005] In particular, the invention relates to a folding unit for carrying out the folding of the tuck-in closing flap which is present in the heads of boxes of tubular shape, once the boxes have been filled with relative products.

[0006] DESCRIPTION OF THE PRIOR ART

[0007] A particular type of boxes used for packaging products is conformed in such a way as to comprise, once opened out into a tubular configuration, two open heads, in which, in at least one of the two heads, a tuck-in closing flap is present which comprises a first main flap, hinged by means of a respective first fold line, to an end edge of a face of the box, and a second auxiliary flap, which is hinged to the first main flap by means of a respective second fold line.

[0008] The first main flap usually has a dimension (area) substantially corresponding to the dimensions (area) of the head of the tubular box which is to be closed and, when the box is opened out into the tubular configuration, the first main flap is located in a configuration that is substantially coplanar to the face of the tubular box to which it is hinged, and the second auxiliary flap is substantially coplanar to the first main flap.

[0009] For the closure of the head of the box, the first main flap must be folded with respect to the face to which it is hinged in a first position of partial folding, in which the first main flap is rotated with respect to the first fold line by an angle of less than 90° in order to near the second auxiliary flap to in proximity of the edge of the face of the box opposite the face to which the first main flap is hinged.

[0010] Therefore, the second auxiliary flap must be folded about the second fold line, with respect to the first main flap, so that the end thereof is facing the open head of the box and, thereafter, the first main flap must be further folded with respect to the first fold line so as to perform a complete rotation of 90°, with respect to the face to which it is hinged, until moving into a closed position of the head, with the second auxiliary flap being contemporaneously pushed and completely inserted internally of the head of the box to constitute a sort of tuck-in which maintains the first main flap closed against the head of the box.

[0011] Figures 1A, 1 B and 1C illustrate a folding sequence of a tuck-in closing flap (L) of a box (A) that is opened out into a tubular configuration, in which the tuck-in closing flap (L) is hinged to an upper face (A1 ) of the box (A) in tubular configuration.

[0012] To carry out the folding operations of the tuck-in closing flap (L), the box (A) once opened out and in a tubular configuration, is supplied along an infeed direction (V) until reaching a pause position (P).

[0013] Then, as illustrated in figure 1A, the first main flap (L1 ) of the tuck-in closing flap (L) is folded downwards, with respect to the upper face (A1 ) of the tubular box (A) and brought into a first position of partial folding (P1 ), following a rotation about the first fold line (F1 ) by an angle of less than 90°, to bring the second auxiliary flap (L2) into a position neared to the open head (T) of the tubular box (A).

[0014] Therefore, as illustrated in figure 1 B, the second auxiliary flap (L2) is folded with respect to the first main flap (L1 ) about the second fold line (F2) so that the end of the second auxiliary flap (L2) is located facing the open head (T) of the tubular box (A).

[0015] Thereafter, as illustrated in figure 1 C, the first main flap (L1 ) is further folded with respect to the first fold line (F1 ) to perform a complete rotation downwards by 90°, with respect to the face (F1 ) of the box to which it is hinged, and to be brought to be completely facing against the head (T) of the box in order to close it, and at the same time, the second auxiliary flap (L2), folded with respect to the first main flap (L1 ), is completely inserted and pushed internally of the head (T) of the box (A) to constitute a tuck-in which maintains the first main flap (L1 ) closed against the head (T) of the box (A).

[0016] Figures 2A, 2B and 2C instead illustrate a folding sequence of a tuck-in closing flap (L) when the tuck-in closing flap (L) is hinged to a lower face (F2) of a box (A) once opened out into a tubular configuration.

[0017] To carry out the folding operations of the tuck-in closing flap (L), the box (A) once opened out and in a tubular configuration, is supplied along an infeed direction (V) until reaching a pause position (P).

[0018] Then, as illustrated in figure 2A, the first main flap (L1 ) of the tuck-in closing flap (L) is folded upwards, with respect to the lower face (F2) of the tubular box (A) and brought into a first position of partial folding (P1 ), following a rotation about the first fold line (F1 ) by an angle of less than 90°, to bring the second auxiliary flap (L2) into a position neared to the open head (T) of the tubular box (A).

[0019] Thereafter, as illustrated in figure 2B, the second auxiliary flap (L2) is folded with respect to the first main flap (L1 ) about the second fold line (F2) in such a way that the end of the second auxiliary flap (L2) is located facing the open head (T) of the box (A).

[0020] Subsequently, as illustrated in figure 2C, the first main flap (L1 ) is further folded with respect to the first fold line (P1 ) to perform a complete rotation upwards by 90°, with respect to the lower face (F2) of the tubular box (A) to which it is hinged, and to be brought to completely facing against the head (T) of the box (A) in order to close it, and at the same time, the second auxiliary flap (L2), folded with respect to the first main flap (L1 ), is completely inserted and pushed internally of the head (T) of the box (A) to constitute a tuck-in which maintains the first main flap (L1 ) closed against the head (T) of the box (A).

[0021] To carry out the folding sequence of the first main flap and the second auxiliary flap of the tuck-in closing flap as previously described, both in the case where the tuck-in closing flap is hinged to the upper face or hinged to the lower face of the tubular box once opened out, at present two distinct folding units are used.

[0022] A first folding unit is used to carry out the folding of the first main flap with respect to the face of the box in a tubular configuration to which it is hinged, to bring it into the first position of partial folding and can rotate it by an angle of less than 90°, while a second folding unit is used both for setting up the folding of the second auxiliary flap with respect to the first main flap of the tuck-in flap and for completing the folding of the first main flap with the complete rotation by 90° and bringing it to abut the head of the box for the closure thereof.

[0023] The first folding unit and the second folding unit are arranged and positioned in two distinct working positions which can usually be located on opposite sides, with respect to the infeed direction of the boxes in tubular configuration, at the pause position in which they are positioned for the folding of the tuck-in closing flap.

[0024] The first folding unit comprises a first drive shaft which is drivable in rotation about a first horizontal axis and a flat cam, which is coaxially mounted on the first drive shaft in order to be driven in rotation about the first horizontal rotation axis, for moving a first folding element in a vertical direction.

[0025] In this regard, the flat cam comprises, on a face thereof, a first annular channel and the first folding element is borne by a first kinematism which is connected, by means of a first roller, to the first annular channel of the first flat cam.

[0026] The first annular channel is conformed in such a way that when the first drive shaft performs a complete rotation, the first flat cam also carries out a complete rotation about the first horizontal rotation axis, and the first roller internally of the first annular channel performs a complete sliding cycle internally of the first annular channel which causes the first folding element to perform, by means of the first kinematism, a complete vertical oscillation.

[0027] In this regard, the first kinematism is configured in such a way as to cause the first folding element to perform a complete oscillation in a vertical direction at each complete rotation of the first drive shaft, and therefore of the flat cam, i.e. at each complete sliding cycle of the first roller internally of the first annular channel.

[0028] In this way, the first folding element can perform a complete oscillation in a vertical direction and be used for carrying out the folding of the first main flap of the tuck-in closing flap and to position it in the first position of partial folding, with a rotation thereof by an angle of less than 90° with respect to the face of the tubular box to which it is hinged.

[0029] For example, in a case in which the tuck-in closing flap is hinged to the upper face of the boxes once placed in a tubular configuration, then the first folding unit, which will be arranged on a first side of the infeed direction of the tubular boxes, the first channel of the first flat cam, and the first kinematism which connects the first folding element to the first roller present in the first channel of the flat cam, will be configured in such a way that, following a complete rotation of the first drive shaft, the first folding element will carry out a first vertical translation downwards, in order to fold the first main flap downwards about the first fold line with respect to the upper face of the tubular box, by an angle of less than 90° and to position it in the first position of partial folding, and, then, once the folding of the tuck-in closing flap has been completed, for the closure of the head of the box, will perform a second vertical translation upwards to return to the start position.

[0030] Instead, in a case in which the tuck-in closing flap is hinged to the lower face of the boxes once set in the tubular configuration, then the first folding unit, arranged, again, on a first side of the infeed direction of the tubular boxes, the first channel of the first flat cam, and the first kinematism which connects the first folding element to the first roller present in the first channel of the flat cam, will be configured in such a way that, following a complete rotation of the first drive shaft, the first folding element will carry out a first vertical translation in an upwards direction, to fold the first main flap upwards about the first fold line with respect to the lower face of the box in tubular configuration, by an angle of less than 90°, in order to position it in the first position of partial folding, and, thereafter, once the folding the tuck-in closing flap has been completed, for the closure of the head of the box, will perform a second vertical translation downwards to return to the start position.

[0031] The second folding unit comprises, in turn, a second drive shaft, drivable in rotation about a second horizontal rotation axis, and a drum cam, coaxially mounted on the second drive shaft and activatable in rotation about the second horizontal rotation axis following the driving in rotation of the second drive shaft, for respectively moving a second folding element and a third folding element.

[0032] In this regard, the drum cam comprises, in the lateral surface thereof, respectively a second annular channel and a third annular channel, with the second folding element being borne by a second kinematism which is connected, by means of a second roller, to the second annular channel of the drum cam and with the third folding element borne by a third kinematism which is connected, by means of a third roller, to the third annular channel of the drum cam.

[0033] The second annular channel is conformed in such a way that when the second drive shaft performs a complete rotation, the second drum cam also carries out a complete rotation about the second horizontal rotation axis, and the second roller performs a complete sliding cycle internally of the second annular channel which causes the second folding element to perform, by means of the second kinematism, a complete horizontal oscillation.

[0034] In this regard, the second kinematism is configured so as to cause the second folding element to perform a complete oscillation in a horizontal direction at each complete rotation of the second drive shaft, and therefore of the drum cam, i.e. at each complete sliding cycle of the second roller internally of the second annular channel.

[0035] In this way, the second folding element can perform a complete oscillation in a horizontal direction and be used for carrying out the folding of the second auxiliary flap of the tuck-in closing flap, about the second fold line, with respect to the first main flap.

[0036] In turn, the third annular channel is conformed in such a way that when the second drive shaft performs a complete rotation, and the drum cam in turn carries out a complete rotation about the second horizontal rotation axis, the third roller performs a complete sliding cycle internally of the third annular channel which causes the third folding element, by means of the third kinematism, to make a complete horizontal oscillation. In this regard, the third kinematism is configured in such a way as to cause the third folding element to perform a complete oscillation in a horizontal direction at each complete rotation of the second drive shaft, and therefore of the drum cam, i.e. at each complete sliding cycle of the third roller internally of the third annular channel.

[0037] In this way, the third folding element can perform a complete oscillation in a horizontal direction and be used to carry out the complete folding of the first main flap of the tuck-in closing flap, and bring it to abut the head of the box for the closure thereof, and the contemporaneous insertion of the second auxiliary flap internally of the head of the box.

[0038] As previously mentioned, in a case in which the tuck-in closing flap is hinged to the upper face or the lower face of the boxes once opened in the tubular configuration, the second folding unit will be arranged on a second side of the infeed direction of the tubular boxes, on the opposite side with respect to the first folding unit.

[0039] In both cases, the second channel and the third channel of the drum cam, the second kinematism, which connects the second folding element to the second roller present in the second channel, and the third kinematism, which connects the third folding element to the third roller internally of the third channel, will be reciprocally conformed and configured in such a way as to carry out the following movements for each complete rotation of the second drive shaft about the second horizontal rotation axis: the second folding element will carry out a first horizontal translation towards the head of the box, in order to abut and fold the second auxiliary flap about the second fold line, with respect to the first main flap which was previously folded by the first folding element in the first position of partial folding, and to position the end of the second auxiliary flap facing the open head of the box; the third folding element will carry out a first horizontal translation towards the head of the box in order to abut and further fold the first main flap with respect to the first fold line, and complete the rotation by 90° thereof with respect to the face of the box hinged thereto, bringing the first main flap completely facing and abutting against the head of the box, in order to close it, and at the same time, the second auxiliary flap, folded with respect to the first main flap, is completely inserted and pushed internally of the head of the box to constitute a tuck-in which maintains the first main flap closed against the head of the box; the second folding element will carry out a second horizontal translation by moving away from the head of the box to return into the initial position, the third folding element will then carry out a second horizontal translation by moving away from the head of the box to return into the initial position.

[0040] Although the use of two distinct folding units, as described above, enables carrying out, in a substantially effective way, the folding of the tuck-in closing flap of the heads of the boxes, there are however various drawbacks.

[0041] In fact, according to packaging needs, and / or the type of products to be packaged, which require corresponding particular conformations of the boxes, it can occur that two successive series of boxes to be used for packaging respective products, once opened out and infed along the infeed direction, have the tuck-in closing flap thereof in different positions, i.e. a first series of boxes can have the tuck-in closing flap above, and a second series of boxes can have the tuck-in closing flap below.

[0042] In these cases, time by time, before proceeding with the packaging operations, it will be necessary to demount the two folding units and invert the positions thereof with respect to the infeed line of the boxes. Further, there may be boxes which, once opened out and infed along the infeed direction, have, in a first head, a closing flap arranged superiorly, and in a second head, a closing flap arranged inferiorly.

[0043] In this case, for the closure of each of the two heads, it will be necessary to use two pairs of folding units such as those described above, arranged in an inverted manner for each of two sides of the infeed direction of the boxes.

[0044] The complication are clear, time by time, for the demounting and remounting of the two folding units, in each of the two sides of the infeed direction of the boxes.

[0045] SUMMARY OF THE INVENTION

[0046] The aim of the present invention is therefore to provide a novel folding unit for folding the tuck-in closing flap of a head of boxes in tubular configuration that is able to obviate the drawbacks described in the foregoing.

[0047] In particular, an aim of the invention is to provide a novel folding unit able to carry out, autonomously and completely, the folding of the tuck-in closing flap for the closure of the head of the tubular boxes.

[0048] The above-mentioned advantages are obtained according to the contents of the claims.

[0049] BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The characteristics of a preferred embodiment of the folding unit object of the present invention will be described in the following description with reference to the appended tables of drawings, in which:

[0051] - figures 1A, 1 B, 1 C, cited in the foregoing, illustrate, in respective schematic perspective views, the advancement of boxes in tubular configuration, and having at least a tuck-in closing flap in a front head thereof and hinged to an upper face thereof, along an infeed direction, wherein the final box on the right is halted in a pause position at which the folding sequence of the tuck-in closing flap takes place for the closure of the head of the box;

[0052] - figures 2A, 2B, 2C, cited in the foregoing, illustrate, in respective schematic perspective views, the advancement of boxes in tubular configuration, and having at least a tuck-in closing flap in a front head thereof and hinged to a lower face thereof, along an infeed direction, wherein the final box on the right is halted in a pause position at which the folding sequence of the tuck-in closing flap takes place for the closure of the head of the box;

[0053] - figures 3A and 3B illustrate, schematically and according to respective perspective views from different angles, the folding unit of the invention in a particular paused configuration before carrying out the folding of the first tuck-in closing flap hinged to an upper face of a box in tubular configuration which is advancing towards a pause position;

[0054] - figures 4A and 4B illustrate, schematically and according to respective perspective views from different angles, the folding unit of the invention in a particular operating step for the folding of the tuck-in closing flap hinged to an upper face of a box in tubular configuration halted in a pause position, in particular of the folding of the first main flap of the tuck-in closing flap towards a first position of partial folding;

[0055] - figures 5A and 5B illustrate, schematically and according to respective perspective views from different angles, the folding unit of the invention in a particular operating step for the folding of the tuck-in closing flap hinged to an upper face of a box in tubular configuration halted in a pause position, in particular of the folding of the first main flap of the tuck-in closing flap towards a first position of partial folding; figures 6A and 6B illustrate, schematically and according to respective perspective views from different angles, the folding unit of the invention in a particular operating step for the folding of the tuck-in closing flap hinged to an upper face of a box in tubular configuration halted in a pause position, in particular of the folding of the first main flap of the tuck-in closing flap in a first position of partial folding;

[0056] - figures 7A and 7B illustrate, schematically and according to respective perspective views from different angles, the folding unit of the invention in a particular operating step for the folding of the tuck-in closing flap hinged to an upper face of a box in tubular configuration halted in a pause position, in particular of the folding of the second auxiliary flap of the tuck-in closing flap with respect to the first main flap;

[0057] - figures 8A and 8B illustrate, schematically and according to respective perspective views from different angles, the folding unit of the invention in a particular operating step for the folding of the tuck-in closing flap hinged to an upper face of a box in tubular configuration halted in a pause position, in particular of the folding of the second auxiliary flap of the tuck-in closing flap with respect to the first main flap;

[0058] - figures 9A and 9B illustrate, schematically and according to respective perspective views from different angles, the folding unit of the invention in a particular operating step for the folding of the tuck-in closing flap hinged to an upper face of a box in tubular configuration halted in a pause position, in particular of the folding of the second auxiliary flap of the tuck-in closing flap with respect to the first main flap;

[0059] - figures 10A and 10B illustrate, schematically and according to respective perspective views from different angles, the folding unit of the invention in a particular operating step for the folding of the tuck-in closing flap hinged to an upper face of a box in tubular configuration halted in a pause position, in particular of the further folding of the first main flap to bring the first main flap facing against the head of the box, with a contemporaneous push and insertion of the second auxiliary flap internally of the head of the box to complete the tuck-in closure;

[0060] - figures 11A and 11 B illustrate, schematically and according to respective perspective views from different angles, the folding unit of the invention in a particular operating step for the folding of the tuck-in closing flap hinged to an upper face of a box in tubular configuration halted in a pause position, in particular of the further folding of the first main flap to bring the first main flap facing against the head of the box, with a contemporaneous push and insertion of the second auxiliary flap internally of the head of the box to complete the tuck-in closure;

[0061] - figure 12 illustrates, in a partial frontal view, some significant components of the folding unit of the invention;

[0062] - figure 13 illustrates, in a section view according to a vertical section plane, other special components of the folding unit of the invention;

[0063] - figures 14A and 14B illustrate, according to respective schematic perspective views from different angles, a possible preferred embodiment of significant components of the folding unit of the invention for carrying out the folding of the first main flap of the tuck-in closing flap and for bringing it into the first position of partial folding, and configured to carry out the folding of the first main flap when the closing flap is hinged to a first upper face of the boxes in tubular configuration;

[0064] - figures 15A, 15B, 15C illustrate, according to respective schematic perspective views from different angles, a possible preferred embodiment of significant components of the folding unit of the invention for setting up the folding of the second auxiliary flap of the tuck-in closing flap with respect to the first main flap, and configured to carry out the folding of the first main flap when the closing flap is hinged to a first upper face of the boxes in tubular configuration;

[0065] - figure 16 is a schematic perspective view, of a possible preferred embodiment of further and other significant components of the folding unit of the invention for carrying out the further folding of the first main flap to bring it to facing the head of the box for the closure thereof, and configured to carry out the further folding of the first main flap when the closing flap is hinged to a first upper face of the boxes in tubular configuration;

[0066] - figures 17A and 17B illustrate, according to respective schematic perspective views from various angles, a possible preferred embodiment of possible other components which can be present in the folding unit of the invention when the tubular boxes also comprise transversal flaps which must be folded, and maintained folded, before carrying out the folding of the tuck-in closing flap;

[0067] - figures 18A and 18B illustrate, according to respective schematic perspective views from different angles, a possible configuration of the folding unit of the invention, in which the components of the folding unit of the invention of figures 14A, 14B are configured and arranged for carrying out the folding of the first main flap of the tuck-in closing flap and for bringing it into the first position of partial folding, when the tuck-in closing flap is hinged to the lower face of a box which is positioned in the pause position;

[0068] - figure 19 illustrates, in a respective schematic perspective view, a possible configuration of the folding unit of the invention in which the components of the folding unit of the invention of figure 15A are configured and arranged for carrying out the folding of the second auxiliary flap of the tuck-in closing flap with respect to the first main flap, when the tuck-in closing flap is hinged to the lower face of a box which is positioned in the pause position;

[0069] - figure 20 illustrates, in a respective schematic perspective view, a possible configuration of the folding unit of the invention in which the components of the folding unit of the invention of figure 16 are configured and arranged for carrying out the further folding of the first main flap to bring it to facing the head of the box for the closure thereof, when the tuck-in closing flap is hinged to the lower face of a box which is positioned in the pause position.

[0070] DESCRIPTION OF THE EMBODIMENTS

[0071] With reference to the accompanying tables of drawings, reference numeral (100) denotes, in its entirety, the folding unit, object of the present invention, for folding a tuck-in closing flap (L) of a head (T) of boxes (A) in a tubular configuration.

[0072] The boxes (A) in tubular configuration are fed along an infeed direction (V) and are time by time positioned in a pause position (P) for folding the tuck-in closing flap (L).

[0073] The boxes (A) in tubular configuration can be advanced along the infeed direction (V), and positioned in the pause position (P), in various ways.

[0074] For example, the machine for advancement of the boxes (A) in tubular configuration along the infeed direction (V) can comprise members / components configured in such a way to advance the boxes alternatingly, or even in movements that are partially alternating or partially continuous.

[0075] The tuck-in closing flap (L) comprises a first main flap (L1 ), hinged by means of a first fold line (F1 ) to a face (D) of the tubular box (A) which is parallel to the infeed direction (V), and a second auxiliary flap (L2), hinged by means of a second fold line (F2), to the first main flap (L1 ). The tuck-in closing flap (L) can be hinged to the upper face of the tubular boxes once opened out into the tubular configuration (as illustrated in figures from 1A to 1 C), or can be hinged to the lower face of the tubular boxes once opened out into the tubular configuration (as illustrated in figures from 2A to 2C).

[0076] The folding unit (100) of the invention is realised and configured to be able to carry out the folding of the tuck-in flap in both situations, as will become more apparent in the following part of the present description.

[0077] The folding unit (100) is suitable to be positioned in an operating position (0) on the side of the infeed line (V) in which position the tuck-in closing flap (L) projects when a box (A) in tubular configuration is positioned in the pause position (P) at which the folding of the tuck-in closing flap is to take place (see for example figures 4A and 4B).

[0078] The folding unit (100) of the invention comprises: a drive shaft (10), which is drivable in rotation about a horizontal rotation axis (H), and transversal to the infeed direction (V) of the boxes (A); a flat cam (1 ), which is coaxially mounted on the drive shaft (10) in such a way as to rotate about the horizontal rotation axis (H) when the drive shaft (10) is driven in rotation about the horizontal rotation axis (H), and comprising, on a respective face, a first annular channel (11 ) (see for example figures 13, 14A, 14B, 18A, 18B) in detail; a drum cam (2), which is coaxially mounted on the drive shaft (10) in such a way as to rotate about the horizontal rotation axis (H) when the drive shaft (10) is activated in rotation about the horizontal rotation axis (H), and comprising, on a respective lateral surface, respectively a second annular channel (21 ) and a third annular channel (22) (see for example in detail figures 13, 15A-15C, 16, 19, 20); a first folding element (3), which is borne by a first kinematism (31 ) connected by means of a first sliding element (32) to the first annular channel (11 ) of the flat cam (1 ), wherein the first sliding element (32) is conformed to slide internally of the first annular channel (11 ) following the driving in rotation of the flat cam (1 ) about the horizontal rotation axis (H); a second folding element (4), which is borne by a second kinematism (41 ) connected by means of a second sliding element (42) to the second annular channel (21 ) of the drum cam (2), wherein the second sliding element (42) is conformed to slide internally of the second annular channel (21 ) following the driving in rotation of the drum cam (2) about the horizontal rotation axis (H); a third folding element (5), which is borne by a third kinematism (51) connected by means of a third sliding element (52) to the third annular channel (22) of the drum cam (2), wherein the third sliding element (52) is conformed to slide internally of the third annular channel (22) following the driving in rotation of the drum cam (2) about the horizontal rotation axis (H).

[0079] In detail: the first annular channel (11 ), the second annular channel (21 ) and the third annular channel (22) are conformed according to respective pathways and reciprocally arranged on the face of the flat cam (1 ) and on the lateral surface of the drum cam (2); the first kinematism (31 ), the second kinematism (41 ) and the third kinematism (51 ) are configured in such a way that, starting from a first angular position (B1 ) of the drive shaft (10) (see figures 4A, 4B), in which the first sliding element (32), the second sliding element (42) and the third sliding element (52) are respectively positioned internally of the first annular channel (11 ), of the second annular channel (21 ), and of the third annular channel (22) so that the first folding element (3), the second folding element (4) and the third folding element (5) are positioned in respective start positions moved away with respect to the tuck-in closing flap (L) and to the head (T) of the tubular box (A) positioned in the pause position (P); following a driving in rotation of the drive shaft (10), about the horizontal rotation axis (H), from the first angular position (B1) towards a second angular position (B2) (sequence of figures 10A, 10B) the following movements are carried out in succession (illustrated in the sequence of figures 4A, 4B, 10A and 10B): the first sliding element (32), sliding internally of the first annular channel (11 ) during the rotation of the flat cam (1 ), causes the first folding element (3) to perform, by means of the first kinematism (31 ), a first vertical displacement towards the first main flap (L1 ) during which the first folding element (3) intercepts the first main flap (L1 ) of the tuck-in closing flap (L) and folds the first main flap (L1 ) about the first fold line (F1 ), rotating it by an angle of less than 90° with respect to the face (D) to which it is hinged, positioning the first main flap (L1 ) in a first position of partial folding (P1 ) in which it is folded towards the head (T) of the box (A) and the second auxiliary flap (L2) is neared to the head (T) of the tubular box (A) (in the sequence of figures from 4A, 4B, to 10A and 10B the first folding element (3) performs a first vertical displacement downwards to fold the first main flap of the tuck-in closing flap hinged to the upper face of the box); the second sliding element (42), sliding internally of the second annular channel (21 ) during the rotation of the drum cam (2), causes the second folding element (4) to perform, by means of the second kinematism (41 ), a first horizontal displacement towards the head (T) of the box (A) during which the second folding element (4) intercepts the second auxiliary flap (L2) of the tuck-in closing flap (L) and folds the second auxiliary flap (L2) about the second fold line (F2) with respect to the first main flap (L1 ), arranging the end of the second auxiliary flap (L2) facing the head (T) of the box (A), the third sliding element (52), sliding internally of the third annular channel (22) during the rotation of the drum cam (2), causes the third folding element (5) to perform, by means of the third kinematism (51 ), a second horizontal displacement towards the head (T) of the box (A) during which the third folding element (5) intercepts the first main flap (L1 ) folded in a first position of partial folding (P1 ) and further folds the first main flap (L1 ) about the first fold line (F1 ), with respect to the face (D) to which it is hinged, arranging the first main flap (L1 ) facing the head (T) of the box (A) while pushing and inserting, at the same time, the second auxiliary flap (L2) internally of the head (T) of the box (A), for the tuck-in closing of the head (T) of the box (A).

[0080] Therefore, owing to the special conformation and configuration of the folding unit of the invention, which includes both the flat cam and the drum cam both mounted coaxially to a single and same drive shaft, and owing to the presence and particular conformation of the first annular channel, on a face of the flat cam, and of the second annular channel and the third annular channel present on the lateral surface of the drum cam, with the rotation of the drive shaft it is possible to drive the three folding elements, one following another, to carry out the folding of all the part of the tuck-in flap so as to fold it against the head of the box, by inserting the second auxiliary flap into the head of the box to obtain a tuck-in closure.

[0081] In this way, it will no longer be necessary, as occurred in the prior art, to use two distinct folding units, on opposite sides with respect to the infeed direction of the boxes in tubular configuration. Further, simply by regulating the angular position (timing) of the flat cam with respect to the first angular position (B1 ) of the drive shaft (10), with the folding unit of the invention it is possible to carry out the folding of the first main flap of the tuck-in closing flap, both when the tuck-in flap is hinged to the upper face of the boxes in tubular configuration, and then to carry out the folding sequence illustrated in figures from 1A to 1 C (such as for example illustrated in the sequence of figures from 1A to 1 C and from 4A, 4B to 10A, 10B) and when the tuck-in flap is hinged to the lower face of the boxes in tubular configuration, and then to carry out the folding sequence illustrated in figures from 2A to 2C.

[0082] Therefore, with the folding unit of the invention, each time there is a size change and / or and change of the type of conformation of the boxes, and a change in the position of the tuck-in closing flap, then simply by regulating the timing of the flat cam with respect to the drive shaft, as well as other simple regulation of components, as will be further described in detail in the following, it will be possible to proceed with the folding operations without performing any other complicated regulating or demounting and remounting of the folding unit on the opposite side of the advancement direction of the boxes, as was required in the prior art.

[0083] Further and other aspects of the folding unit of the invention are described in the following.

[0084] The first annular channel (11 ), the second annular channel (21 ) and the third annular channel (22) are conformed according to respective pathways and reciprocally arranged on the face of the flat cam (1 ) and on the lateral surface of the drum cam (2), and the first kinematism (31 ), the second kinematism (41 ) and the third kinematism (51 ) are configured in such a way that, with the completion of a complete rotation of the drive shaft (10) about the horizontal rotation axis (H), for the repositioning of the drive shaft (10) in the first angular position (B1 ), the further following movements are carried out (see figures from 10A, 10B to 11 A, 11 B): the first sliding element (32), sliding further internally of the first annular channel (11 ) during the further rotation of the flat cam (1 ), causes the first folding element (3) to perform, by means of the first kinematism (31 ), a second vertical displacement in a moving away direction from the head (T) of the box (vertical displacement in the opposite direction with respect to the previous movement, therefore upwards in the case in which the tuck-in closing flap was hinged to the upper face of the box) returning the first folding element (3) into the respective moved-away starting position; the second sliding element (42), sliding further internally of the second annular channel (21 ) during the further rotation of the drum cam (2), causes the second folding element (4) to perform, by means of the second kinematism (42), a third horizontal displacement in a moving away direction from the head (T) of the box (A) (in an opposite direction to the preceding), returning the second folding element (4) into the respective moved-away starting position; the third sliding element (52), sliding further internally of the third annular channel (22) during the further rotation of the drum cam (2), causes the third folding element (5) to perform, by means of the third kinematism (51 ), a fourth horizontal displacement in a moving away direction from the head (T) of the box (A) (in an opposite direction to the preceding), returning the third folding element (5) into the respective moved-away starting position.

[0085] According to the preferred but not exclusive embodiment illustrated in the figures, the first kinematism (31 ) can be made in such a way as to comprise (see for example figures 14A, 14B, or figures 18A, 18B): a first lever (310) which is rotatably constrained, on a first side, to a frame (101 ) of the folding unit (100) about a first rotation axis (V1 ) parallel to the horizontal rotation axis (H) of the drive shaft (10) and which is connected to the first sliding element (32), and a second lever (311 ) which is rotatably constrained, at a respective first side, to the frame (101 ) of the folding unit (100) about a second rotation axis (V2) parallel to the first rotation axis (V1 ) and to the horizontal rotation axis (H) of the drive shaft (10), wherein the first lever (310) and the second lever (311 ) are rotatably connected, at a respective second side thereof, to an upright element (312) which bears the first folding element (3).

[0086] In particular, and preferably, the upright element (312) can comprise, longitudinally, a slot (313) which enables connection of the first lever (310) and the second lever (311 ) to the upright element (312) in different working positions (W1 , W2), in such a way as to vary and regulate the position of the first folding element (3) with respect to the position of the tuck-in closing flap when the tubular box is positioned in the pause position (P).

[0087] For example, in figures 14A and 14B, the upright element (312), which bears the first folding element (3), is connected to the first lever (310) and to the second lever (311 ) in a first working position (W1 ).

[0088] The arrangement of the upright element (312) in the first working position (W1 ), as shown in figures 14A and 14B, together with the regulation of the timing of the flat cam (1 ) with respect to the drive shaft (10), enables using the folding unit (100) of the invention to carry out the folding of the main flap of the tuck-in closing flap when the tuck-in flap is hinged to the upper face of the boxes in tubular configuration.

[0089] Instead, in figures 18A and 18B, the upright element (312) which bears the first folding element (3), is connected to the first lever (310) and to the second lever (311 ) in a second working position (W1 ), in which the first folding element (3) will be at a different (lower) height with respect to the infeed line of the tubular boxes.

[0090] The arrangement of the upright element (312) in the second working position (W2) as shown in figures 18A and 18B, together with the regulation of the timing of the flat cam (1 ) with respect to the drive shaft (10), enables using the folding unit (100) of the invention to carry out the folding of the main flap of the tuck-in closing flap when the tuck-in flap is hinged to the lower face of the boxes in tubular configuration.

[0091] Further, owing to the presence of the slot along the upright element, it is possible to regulate the position (height) of the first folding element between a minimum height and a maximum height, with respect to the infeed line of the boxes, which enables carrying out the folding of the tuck-in closing flap even in a case of size changes (dimensions) of the boxes, without having to carry out the demounting and remounting of the folding unit in different positions.

[0092] According to the preferred but not exclusive embodiment illustrated in the figures, in particular see figures from 15A to 15C and figure 19, the second kinematism

[0093] (41 ) can be made in such a way as to comprise: a third lever (410) which is connected, on a first side, to the second sliding element

[0094] (42), and which is rotatingly constrained, at a second side, to the frame (101 ) of the folding unit (100) about a third rotation axis (V3) perpendicular to a vertical plane containing the horizontal rotation axis (H) of the drive shaft (10), a fourth lever (411 ) which is hinged, on a respective side, to the third lever (410) coaxially to the third rotation axis (V3), and a first arm (412), hinged to a second side of the fourth lever (411 ) which bears the second folding element (4). Further, as can be observed in detail in some of figures from 3A to 3B and from 11 A, a 11 B, the second kinematism (41 ) comprises a first horizontal guide element

[0095] (413), arranged parallel to the horizontal rotation axis (H) of the drive shaft (10) and transversally to the infeed direction (V) of the boxes (A), and a first sleeve

[0096] (414), slidably mounted on the first horizontal guide element (413), wherein the first arm (412) is connected to the first sleeve (414).

[0097] To set up the folding unit to carry out the folding of the second auxiliary flap of the tuck-in closing flap when the tuck-in flap is hinged to the upper face or lower face of a box in tubular configuration, it will be sufficient to replace the first arm (412) with another first arm (412) of adequate length.

[0098] For example, in figures from 15A to 15C, the second kinematism (41 ) of the folding unit comprises a first arm (412) of a first length (E1 ), suitable to set up the folding unit to carry out the folding of the second auxiliary flap of the tuck-in closing flap when the tuck-in flap is hinged to the upper face of the boxes in tubular configuration, while in figure 19 the second kinematism (41 ) of the folding unit comprises a first arm (412) of a second length (E2), suitable to set up the folding unit to carry out the folding of the second auxiliary flap of the tuck-in closing flap when the tuck-in closing flap is hinged to the lower face of the boxes in tubular configuration.

[0099] Time by time, and simply by using a first arm of an adequate length, it will be possible to adjust the folding unit to the particular dimensions, i.e. to the size, of the tubular boxes with respect to the position of the tuck-in closing flap, without having to carry out any demounting and remounting of the folding unit into different positions with respect to the infeed direction of the boxes.

[0100] According to the preferred but not exclusive embodiment illustrated in the figures, the third kinematism (51 ) can be made in such a way as to comprise: a fifth lever (510), connected to the third sliding element (52), a sixth lever (511 ) which is rotatably constrained to the frame (101 ) of the folding unit (100) about a fourth rotation axis (V4) perpendicular to a vertical plane containing the horizontal rotation axis (H) of the drive shaft (10), a seventh lever (512) hinged, on a first side, to the fifth lever (510) and, at a second side, to the sixth lever (511 ), an eighth lever (513) which is hinged, at a respective side, to the sixth lever (511 ), coaxially to the fourth rotation axis (V4), and a second arm (514), hinged to a second side of the eighth lever (513) which bears the third folding element (5).

[0101] Further, as can be observed in detail in some of figures from 3A to 3B and from 11 A, a 11 B, the third kinematism (51 ) can comprise a second horizontal guide element (515), arranged parallel to the horizontal rotation axis (H) of the drive shaft (10) and transversally to the infeed direction (V) of the boxes (A), and a second sleeve (516), mounted slidably on the second horizontal guide element (515), wherein the second arm (514) is connected to the second sleeve (516).

[0102] To set up the folding unit to carry out the complete folding of the first main flap of the tuck-in closing flap, and arrange it completely facing the head of the box, when the tuck-in closing flap is hinged to the upper face or lower face of a box in tubular configuration, it will be sufficient to replace the first arm (514) with another second arm (514) of adequate length.

[0103] For example, in figure 16, the third kinematism (51 ) of the folding unit comprises a second arm (514) of a first length (C1 ), suitable to carry out the complete folding of the first main flap of the tuck-in closing flap, and arrange it completely facing the head of the box, when the closing flap is hinged to a first upper face of the boxes in tubular configuration, while in figure 20 the third kinematism (51 ) of the folding unit comprises a second arm (514) of a second length (C2), suitable to carry out the complete folding of the first main flap of the tuck-in closing flap, and arrange it completely facing the head of the box, when the closing flap is hinged to a first upper face of the boxes in tubular configuration.

[0104] Therefore, time by time, and simply by using a second arm of an adequate length, it will be possible to adjust the folding unit to the particular dimensions, i.e. to the size, of the tubular boxes, with respect to the position of the tuck-in closing flap, without having to carry out any demounting and remounting of the folding unit into different positions with respect to the infeed direction of the boxes.

[0105] Further, in another special aspect, the folding unit (100) can be made in such a way that the drum cam (2) comprises, in a respective head (29), a fourth annular channel (23) (see in particular figures 17a and 17B), and with the folding unit (100) comprising a fourth folding element (6), which is borne by a fourth kinematism (61 ) connected by means of a fourth sliding element (62) to the fourth annular channel (23) of the drum cam (2), wherein the fourth sliding element (62) is conformed so as to slide internally of the fourth annular channel (23) following the driving in rotation of the drum cam (2) about the horizontal rotation axis (H).

[0106] In greater detail: the fourth annular channel (23) is conformed according to a respective pathway and arranged on the head (29) of the drum cam (2); and wherein the fourth kinematism (61 ) is configured in such a way that, following the activation in rotation of the drive shaft (10), about the horizontal rotation axis (H), and for each complete rotation of the drive shaft (10) (sequence of figures from 3A-3B to 11A-11 B) the fourth folding element (6) performs an alternative translation along a movement direction parallel to the infeed direction (V) of the boxes (A), between a retracted position with respect to the pause position (P), and an advanced position at the pause position (P), in order to maintain folded transversal flaps present in the head (T) of the box (A) and previously bent during the advancement of the box (A) along the infeed direction (V) towards the pause position (P).

[0107] According to the special but not exclusive embodiment, in the special embodiment illustrated in the figures, the fourth kinematism (61 ) can be made in such a way as to comprise: a ninth lever (610), connected to the fourth sliding element (62), and which is rotatably constrained to the frame (101 ) of the folding unit (100) about a fifth rotation axis (V5) parallel to the horizontal rotation axis (H) of the drive shaft (10), a tenth lever (611 ) rigidly mounted on a connecting shaft (612) which is rotatably constrained to the frame (101 ) of the folding unit (100) about a sixth rotation axis (V6) parallel to the fifth rotation axis (V5), wherein the tenth lever (611 ) and the ninth lever (610) are reciprocally coupled to one another by means of respective cogged coupling profiles (613, 614), the fourth kinematism (61 ) further comprising an eleventh lever (615) rigidly mounted on the connecting shaft (612), a twelfth lever (616), hinged, on a first side, to the eleventh lever (615), and on the other side, to a third arm (617) which bears the fourth folding element (6).

[0108] The fourth kinematism (61 ) can comprise a fourth horizontal guide element (618), arranged parallel to the infeed direction (V) of the boxes (A), internally hollow, and a rod (619), slidably mounted internally of the fourth horizontal guide element (618), and connected to the third arm (617).

[0109] The first kinematism (31 ), the second kinematism (41 ), the third kinematism (51 ) and the fourth kinematism (61 ), for the movement, respectively, of the first folding element (3), the second folding element (4), the third folding element (5) and the fourth folding element (6) can also be realised using other configurations and conformations, different to those described in the foregoing, but in any case equivalent thereto in order to carry out the displacement of the first folding element (3), the second folding element (4), the third folding element (5) and the fourth folding element (6), as described herein above, and in any case falling withing the scope of protection of the invention.

Claims

CLAIMS1) A folding unit (100) for folding a tuck-in closing flap (L) of a head (T) of boxes (A) in a tubular configuration, wherein the boxes (A) in tubular configuration are fed along an infeed direction (V) and are time by time positioned in a pause position (P) for folding the tuck-in closing flap (L), with the tuck-in closing flap (L) comprising a first main flap (L1 ), hinged by means of a first fold line (F1 ) to a face (D) of the tubular box (A) which is parallel to the infeed direction (V), and a second auxiliary flap (L2), hinged by means of a second fold line (F2), to the first main flap (L1 ), wherein the folding unit (100) is positioned in an operating position (0) on the side of the infeed line (V) in which position the tuck-in closing flap (L) projects when a box (A) in tubular configuration is positioned in the pause position (P), wherein the folding unit (100) comprises: a drive shaft (10), activatable in rotation about a horizontal rotation axis (H), and transversal to the infeed direction (V) of the boxes (A); a flat cam (1 ), coaxially mounted on the drive shaft (10) in such a way as to rotate about the horizontal rotation axis (H) when the drive shaft (10) is activated in rotation about the horizontal rotation axis (H), and comprising, on a respective face, a first annular channel (11 ); a drum cam (2), coaxially mounted on the drive shaft (10) in such a way as to rotate about the horizontal rotation axis (H) when the drive shaft (10) is activated in rotation about the horizontal rotation axis (H), and comprising, on a respective lateral surface, respectively a second annular channel (21 ) and a third annular channel (22), a first folding element (3), which is borne by a first kinematism (31 ) connected bymeans of a first sliding element (32) to the first annular channel (11 ) of the flat cam (1 ), wherein the first sliding element (32) is conformed to slide internally of the first annular channel (11 ) following the driving in rotation of the flat cam (1 ) about the horizontal rotation axis (H); a second folding element (4), which is borne by a second kinematism (41 ) connected by means of a second sliding element (42) to the second annular channel (21 ) of the drum cam (2), wherein the second sliding element (42) is conformed to slide internally of the second annular channel (21 ) following the driving in rotation of the drum cam (2) about the horizontal rotation axis (H); a third folding element (5), which is borne by a third kinematism (51) connected by means of a third sliding element (52) to the third annular channel (22) of the drum cam (2), wherein the third sliding element (52) is conformed to slide internally of the third annular channel (22) following the driving in rotation of the drum cam (2) about the horizontal rotation axis (H); wherein the first annular channel (11 ), the second annular channel (21 ), the third annular channel (22) are conformed according to respective pathways and reciprocally arranged on the face of the flat cam (1 ) and on the lateral surface of the drum cam (2), and wherein the first kinematism (31 ), the second kinematism (41 ) and the third kinematism (51 ) are configured in such a way that, starting from a first angular position (B1 ) of the drive shaft (10), in which the first sliding element (32), the second sliding element (42) and the third sliding element (52) are respectively positioned internally of the first annular channel (11 ), of the second annular channel (21 ), and of the third annular channel (22) so that the first folding element (3), the second folding element (4) and the third folding element (5) are positioned in respective start positions moved away with respect to the tuck-inclosing flap (L) and to the head (T) of the tubular box (A) positioned in the pause position (P), following the driving in rotation of the drive shaft (10), about the horizontal rotation axis (H), from the first angular position (B1 ) towards a second angular position (B2) the following movements are carried out in succession: the first sliding element (32), sliding internally of the first annular channel (11 ) during the driving in rotation of the flat cam (1 ), causes the first folding element (3) to perform, by means of the first kinematism (31 ), a first vertical displacement towards the first main flap (L1 ) during which the first folding element (3) intercepts the first main flap (L1 ) of the tuck-in closing flap (L) and folds the first main flap (L1 ) about the first fold line (F1 ), rotating it by an angle of less than 90° with respect to the face (D) to which it is hinged, positioning the first main flap (L1 ) in a first position of partial folding (P1 ) in which it is folded towards the head (T) of the box (A) and the second auxiliary flap (L2) is neared to the head (T) of the tubular box (A); the second sliding element (42), sliding internally of the second annular channel (21 ) during the rotation of the drum cam (2), causes the second folding element (4) to perform, by means of the second kinematism (41 ), a first horizontal displacement towards the head (T) of the box (A) during which the second folding element (4) intercepts the second auxiliary flap (L2) of the tuck-in closing flap (L) and folds the second auxiliary flap (L2) about the second fold line (F2) with respect to the first main flap (L1 ), arranging the end of the second auxiliary flap (L2) facing the head (T) of the box (A), the third sliding element (52), sliding internally of the third annular channel (22) during the rotation of the drum cam (2), causes the third folding element (5) to perform, by means of the third kinematism (51 ), a second horizontal displacementtowards the head (T) of the box (A) during which the third folding element (5) intercepts the first main flap (L1 ) folded in a first position of partial folding (P1 ) and further folds the first main flap (L1 ) about the first fold line (F1 ), with respect to the face (D) to which it is hinged, arranging the first main flap (L1 ) facing the head (T) of the box (A) while pushing and inserting, at the same time, the second auxiliary flap (L2) internally of the head (T) of the box (A), for the tuck-in closing of the head (T) of the box (A).2) The folding unit (100) as claimed in claim 1 , wherein the first annular channel (11 ), the second annular channel (21 ) and the third annular channel (22) are conformed according to respective pathways and reciprocally arranged on the face of the flat cam (1 ) and on the lateral surface of the drum cam (2), and wherein the first kinematism (31 ), the second kinematism (41 ) and the third kinematism (51 ) are configured in such a way that, with the completion of a complete rotation of the drive shaft (10) about the horizontal rotation axis (H), for the repositioning of the drive shaft (10) in the first angular position (B1 ), the further following movements are carried out: the first sliding element (32), sliding further internally of the first annular channel (11 ) during the further rotation of the flat cam (1 ), causes the first folding element (3) to perform, by means of the first kinematism (31 ), a second vertical displacement in a moving away direction from the head (T) of the box, returning the first folding element (3) into the respective moved-away starting position; the second sliding element (42), sliding further internally of the second annular channel (21 ) during the further rotation of the drum cam (2), causes the second folding element (4) to perform, by means of the second kinematism (42), a third horizontal displacement in a moving away direction from the head (T) of the box(A), returning the second folding element (4) into the respective moved-away starting position; the third sliding element (52), sliding further internally of the third annular channel (22) during the further rotation of the drum cam (2), causes the third folding element (5) to perform, by means of the third kinematism (51 ), a fourth horizontal displacement in a moving away direction from the head (T) of the box (A), returning the third folding element (5) into the respective moved-away starting position.3) The folding unit (100) as claimed in claim 2, wherein the first kinematism (31 ) comprises a first lever (310) which is rotatably constrained, on a first side, to a frame (101 ) of the folding unit (100) about a first rotation axis (V1 ) parallel to the horizontal rotation axis (H) of the drive shaft (10) and which is connected to the first sliding element (32), and a second lever (311 ) which is rotatably constrained, at a respective first side, to the frame (101 ) of the folding unit (100) about a second rotation axis (V2) parallel to the first rotation axis (V1 ) and to the horizontal rotation axis (H) of the drive shaft (10), wherein the first lever (310) and the second lever (311 ) are rotatably connected, at a respective second side thereof, to an upright element (312) which bears the first folding element (3).4) The folding unit (100) as claimed in claim 3, wherein the upright element (312) comprises, longitudinally, a slot (313) which enables connection of the first lever (310) and the second lever (311 ) to the upright element (312) in different working positions (W1 , W2), in such a way as to vary and regulate the position of the first folding element (3) with respect to the position of the tuck-in closing flap when the tubular box is positioned in the pause position (P).5) The folding unit (100) as claimed in any one of claims from 2 to 4, wherein thesecond kinematism (41 ) comprises a third lever (410) which is connected, on a first side, to the second sliding element (42), and which is rotatingly constrained, at a second side, to the frame (101 ) of the folding unit (100) about a third rotation axis (V3) perpendicular to a vertical plane containing the horizontal rotation axis (H) of the drive shaft (10), a fourth lever (411 ) which is hinged, on a respective side, to the third lever (410) coaxially to the third rotation axis (V3), and a first arm (412), hinged to a second side of the fourth lever (411 ) which bears the second folding element (4).6) The folding unit (100) as claimed in claim 5, wherein the second kinematism (41 ) comprises a first horizontal guide element (413), arranged parallel to the horizontal rotation axis (H) of the drive shaft (10) and transversally to the infeed direction (V) of the boxes (A), and a first sleeve (414), slidably mounted on the first horizontal guide element (413), and wherein the first arm (412) is connected to the first sleeve (414).7) The folding unit (100) as claimed in any one of claims from 2 to 6, wherein the third kinematism (51 ) comprises a fifth lever (510), connected to the third sliding element (52), a sixth lever (511 ) which is rotatably constrained to the frame (101 ) of the folding unit (100) about a fourth rotation axis (V4) perpendicular to a vertical plane containing the horizontal rotation axis (H) of the drive shaft (10), a seventh lever (512) hinged, on a first side, to the fifth lever (510) and, at a second side, to the sixth lever (511 ), an eighth lever (513) which is hinged, at a respective side, to the sixth lever (511 ), coaxially to the fourth rotation axis (V4), and a second arm (514), hinged to a second side of the eighth lever (513) which bears the third folding element (5).8) The folding unit (100) as claimed in claim 7, wherein the third kinematism (51 )comprises a second horizontal guide element (515), arranged parallel to the horizontal rotation axis (H) of the drive shaft (10) and transversally to the infeed direction (V) of the boxes (A), and a second sleeve (516), mounted slidably on the second horizontal guide element (515), and wherein the second arm (514) is connected to the second sleeve (516).9) The folding unit (100) as claimed in any one of claims from 1 to 8, wherein the drum cam (2) comprises, in a respective head (29), a fourth annular channel (23), with the folding unit (100) comprising a fourth folding element (6), which is borne by a fourth kinematism (61 ) connected by means of a fourth sliding element (62) to the fourth annular channel (23) of the drum cam (2), wherein the fourth sliding element (62) is conformed so as to slide internally of the fourth annular channel (23) following the driving in rotation of the drum cam (2) about the horizontal rotation axis (H), wherein the fourth annular channel (23) is conformed according to a respective pathway and arranged on the head (29) of the drum cam (2), and wherein the fourth kinematism (61 ) is configured in such a way that, following the driving in rotation of the drive shaft (10), about the horizontal rotation axis (H), and for each complete rotation of the drive shaft (10), the fourth folding element (6) performs an alternating translation along a movement direction parallel to the infeed direction (V) of the boxes (A), between a retracted position with respect to the pause position (P) and an advanced position at the pause position (P), in order to maintain transversal flaps present in the head (T) of the box (A) folded which have been previously folded during the advancement of the box (A) along the infeed direction (V) towards the pause position (P).10) The folding unit (100) as claimed in claim 9, wherein the fourth kinematism(61 ) comprises a ninth lever (610), connected to the fourth sliding element (62), and which is rotatably constrained to the frame (101 ) of the folding unit (100) about a fifth rotation axis (V5) parallel to the horizontal rotation axis (H) of the drive shaft (10), a tenth lever (611 ) rigidly mounted on a connecting shaft (612) which is rotatably constrained to the frame (101 ) of the folding unit (100) about a sixth rotation axis (V6) parallel to the fifth rotation axis (V5), wherein the tenth lever(611 ) and the ninth lever (610) are reciprocally coupled to one another by means of respective cogged coupling profiles (613, 614), the fourth kinematism (61 ) further comprising an eleventh lever (615) rigidly mounted on the connecting shaft(612), a twelfth lever (616), hinged, on a first side, to the eleventh lever (615), and on the other side, to a third arm (617) which bears the fourth folding element (6).11 ) The folding unit (100) as claimed in claim 10, wherein the fourth kinematism (61 ) comprises a fourth horizontal guide element (618), arranged parallel to the infeed direction (V) of the boxes (A), internally hollow, and a rod (619), slidably mounted internally of the fourth horizontal guide element (618), and connected to a third arm (617).

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