PACKAGING UNIT FOR PACKAGING ARTICLES IN BOXES AND METHOD FOR PACKAGING ARTICLES IN BOXES

Abstract

A packaging unit for packaging articles in boxes, including a mandrel, a movement device, a feeding device, a folding device, and an actuation device. The mandrel is configured to accommodate at least one of said articles inside it. The movement device is configured to move said mandrel along a movement trajectory at a desired movement speed. The feeding device is configured to feed at least one blank towards said mandrel along a feeding trajectory which intersects said movement trajectory. The folding device is intended to abut said blank and is configured to cooperate with said mandrel to fold said blank around said mandrel when said blank is positioned between said mandrel and said folding device to form one of said boxes. The actuation device is configured to displace said folding device along at least one folding stroke with an accompanying speed having at least one accompanying component with the same direction as the movement speed of the mandrel and modulus lower than the movement modulus in said folding stroke.

Claims

1.-15. (canceled)

16. A packaging unit for packaging articles in boxes, comprising: a mandrel configured to accommodate at least one of said articles inside it, a movement device configured to move said mandrel along a movement trajectory at a movement speed, the movement speed having a movement modulus and a movement direction, a feeding device configured to feed at least one blank towards said mandrel along a feeding trajectory which intersects said movement trajectory, a folding device configured to abut said blank and configured to fold said blank around said mandrel when said blank is positioned between said mandrel and said folding device, to form one of said boxes, and an actuation device configured to displace said folding device along at least one folding stroke, the at least one folding stroke having an accompanying speed, the accompanying speed having at least one accompanying component with a same direction as the movement direction, the accompanying component having an accompanying modulus, wherein the accompanying modulus is lower than the movement modulus.

17. The packaging unit according to claim 16, wherein said accompanying speed is parallel to said movement speed in said folding stroke.

18. The packaging unit according to claim 16, wherein said actuation device is configured to displace said folding device (a) along a first portion of said folding stroke in which said folding device is spaced apart from said blank, and (b) along a second portion of said folding stroke in which said folding device is in contact with said blank to fold said blank on said mandrel.

19. The packaging unit according to claim 16, wherein said folding device comprises a first folding element and a second folding element, the first folding element and the second folding element arranged to respectively abut a first panel and a second panel of said blank, said first panel and said second panel being provided on opposite sides of said blank with respect to an advancement plane defined by said mandrel when moved along said movement trajectory.

20. The packaging unit according to claim 19, at least one of said first folding element and second folding element comprising: a folding portion shaped to interact with said blank, and a movement arm extending from said folding portion and coupled to said actuation device to actuate said at least one of said first folding element and second folding element.

21. The packaging unit according to claim 19, the first folding element and the second folding element each comprising: a respective folding portion shaped to interact with said blank, and a movement arm extending from said folding portion; said actuation device comprising: a first actuation element arranged to actuate said first folding element, and a second actuation element arranged to actuate said second folding element.

22. The packaging unit according to claim 16, wherein said actuation device is configured to actuate said folding device along said folding stroke between a first position and a second position at an accompanying speed and to further actuate said folding device from said second position to said first position at a return speed with approach to said mandrel, said return speed having a return direction opposite to said movement direction.

23. The packaging unit according to claim 20, wherein said folding portion defines a first impact surface to interact with said blank, the first impact surface having a rounded shape.

24. The packaging unit according to claim 23, wherein the rounded shape of the first impact surface is convex toward said blank.

25. The packaging unit according to claim 16, the packaging unit further comprising a retaining device displaceable between an operating position and a non-operating position, wherein, in the operating position, said retaining device approaches a first abutment surface to retain said blank against said first abutment surface, and wherein, in the non-operating position, said retaining device is spaced apart from said first abutment surface.

26. The packaging unit according to claim 25, the packaging unit further comprising an actuation member configured to displace said retaining device along an actuation trajectory to bring said retaining device towards said operating position.

27. A method for packaging articles in boxes comprising: providing a mandrel configured to accommodate at least one of said articles, providing a folding device configured to fold a blank around said mandrel to form said box, providing a feeding device configured to feed at least one blank towards said mandrel, depositing at least one of said articles in a mandrel, moving said mandrel along a movement trajectory at a movement speed, the movement speed having a movement modulus and a movement direction, positioning a blank along said movement trajectory of said mandrel in an advanced position with respect to said mandrel so that said blank is interposed between said folding device and said mandrel, moving said folding device along at least one folding stroke of said movement trajectory with an accompanying speed, the accompanying speed having at least one accompanying component with a same direction as the movement direction, the accompanying component having an accompanying modulus, wherein the accompanying modulus is lower than the movement modulus.

28. The method according to claim 27, the moving said folding device comprising the accompanying speed that is parallel to said movement speed in said folding stroke.

29. The method according to claim 27, wherein said folding device comprises a first folding element and a second folding element and wherein said moving said folding device comprises displacing said first folding element at the accompanying speed and displacing said second folding element at the accompanying speed.

30. The method according to claim 29, wherein said moving said folding device comprises displacing said first folding element and displacing said second folding element in a synchronised manner.

31. The method according to claim 27, wherein said folding device comprises a first folding element and a second folding element and wherein said moving said folding device comprises actuating said first folding element at a first accompanying speed and further actuating said second folding element at a second accompanying speed, said second accompanying speed having the same direction as said first accompanying speed and a second modulus lower than a first modulus of said first accompanying speed.

32. The packaging unit for packaging articles in boxes according to claim 16, wherein said packaging unit further comprises a plurality of mandrels, wherein each mandrel is configured to accommodate at least one of said articles inside it, wherein said movement device is configured to move each mandrel along said movement trajectory, and wherein said folding device is configured to fold one of a plurality of blanks around one of the plurality of mandrels when said one of the plurality of blanks is positioned between said one of the plurality of mandrels and said folding device to form one of said boxes.

Description

[0214] FIGS. 1 and 2 are two schematic plan views of an embodiment example of a packaging unit in accordance with the present solution;

[0215] FIG. 3-5 are partial schematic views of a folding device and of a mandrel of the packaging unit of FIG. 1 and of a blank in three distinct positions of use;

[0216] FIG. 6-7 are partial schematic views of a folding device of the packaging unit of FIG. 1 respectively in a first position and in a second position;

[0217] FIG. 8 is a schematic figure of a folding device and of a mandrel of the packaging unit of FIG. 1 and of a blank in a position of use;

[0218] FIG. 9 is a schematic view of a blank usable in the packaging unit of FIG. 1

[0219] FIGS. 10A and 10B are two interrupted graphs of a movement trajectory of the packaging unit of FIG. 1;

[0220] FIG. 11 is a schematic view of a portion of the packaging unit of FIG. 1;

[0221] FIG. 12 is a schematic view showing the movement of a retaining element of the packaging unit of FIG. 1;

[0222] FIG. 13 is a schematic figure of a folding device and of a mandrel of a further version of the packaging unit of the invention and of a blank in a position of use;

[0223] FIGS. 14A and 14B are two interrupted graphs of a movement trajectory of the packaging unit in the version of FIG. 13.

[0224] In the accompanying figures, a packaging unit made in accordance with this solution is indicated as a whole with 100. The packaging unit 100 is of the wrap-around type, performing the packaging by wrapping a box around an article 1 to be packaged. In the present example the article 1, better visible in FIG. 3 or 4, consists of one or more flexible bags, filled with predetermined quantities of bulk products in the form of a discrete particulate consisting of granules and/or corn flakes and suitably sealed. The box 2, better visible in FIG. 5, is formed by wrapping a blank 7 around a mandrel 10 bearing the article 1, as better clarified below.

[0225] The packaging unit 100 is provided to move objects along a process direction indicated with F in the Figures.

[0226] The packaging unit 100 is fed by a straight conveyor belt 101 on which the articles 1 to be packaged are conveyed, which in the present example consist of the bags described above, coming from the respective filling and sealing plant. The conveyor belt 101 transports the articles 1 to a first unloading end 102 at which the articles 1 are picked up by a transfer carousel 103 which is provided to pick up an article 1 to be packaged from the conveyor belt 101 and to transfer it to the packaging unit 100 in which the execution of a wrapping step of a box is provided, as better clarified below.

[0227] The packaging unit 100 comprises in its more general units a forming carousel 3 which is provided to receive the articles 1 from the transfer carousel 103 and to form a box 2, a feed carousel 5 for feeding blanks 7 to the forming carousel 3 and an outlet carousel 6, intended to pick up the boxes 2 formed by the forming carousel 3 and to deposit them on an evacuation belt 8 through which the boxes 2 are transported to subsequent processing units provided in the packaging unit 100.

[0228] The forming carousel 3, the feed carousel 5 and the outlet carousel 6 are brought into rotation, by means of respective movement devices not shown, in order to be rotatable about respective axes of rotation which are substantially parallel to a vertical direction that is indicated in the figures generally with Z and that is perpendicular to the plane of FIGS. 1 and 2.

[0229] The forming carousel 3 is provided with a plurality of mandrels 10, each mandrel 10 is configured to accommodate one of the articles 1 inside it and is operatively connected to a movement device of the forming carousel 3 to be displaced along a movement trajectory M at a desired movement speed VM, as better explained below. The movement trajectory M lies on an advancement plane 200 of the mandrel 10 and is a line oriented in the shape of an arc of circumference. The movement speed VM is a vector having at each point a direction tangent to the movement trajectory M and a desired modulus M2 which is constant along the movement trajectory M as best schematized in FIG. 10A-10B. The advancement plane of the mandrel 200 has an XY orientation in an orthogonal Cartesian reference system XYZ.

[0230] The feeding carousel 5 comprises a plurality of feeding devices 30, each configured to feed a blank 7 towards a mandrel 10. Each feeding device 30 is configured to pick up a single blank 7 from a group of blanks stacked in a hopper 700 and to bring it to the forming carousel 3 and is configured to feed the blank 7 along a feeding trajectory which intersects the movement trajectory M. Each feeding device 30 comprises a plurality of retaining elements 31 arranged to retain the blank 7 in different portions thereof. Each retaining element 31 comprises a suction cup, not shown in the Figures, operatively connected to a suction device, also not visible in the Figures, and arranged to releasably retain a desired portion of a blank, as better clarified below. An application device 701 is also provided which is intended to apply a desired amount of glue on an edge portion 7D of the blank 7, when the blank 7 is retained on a retaining device 30 before feeding it to the forming carousel 3.

[0231] The packaging unit 100 further comprises a folding device 20, better visible in FIGS. 6 and 7, intended to abut the blank 7 and configured to cooperate with the mandrel 10 to fold the blank 7 around the mandrel 10, as better clarified below. The packaging unit 100 further comprises an actuation device 40 configured to displace the folding device 20 along at least one folding stroke P which, in the version shown, is defined on the movement trajectory M of the mandrel 10.

[0232] The packaging unit 100 further comprises a guide device 15, provided immediately downstream of the folding device 20 and comprising a first guide plate 16 and a second guide plate 17 that are mutually facing and defining a housing 18 for a box to be formed. The first guide plate 16 and the second guide plate 17 extend for a guide stroke G of the movement trajectory M. The first guide plate 16 and the second guide plate 17 extend respectively between a first end 16A, 17A and a second end 16B, 17B, the first end 16A, 17A being provided in a backward position with respect to the second end 16B, 17B and the first guide plate 16 and the second guide plate 17 allow to maintain the shape of the box 2 being formed avoiding unwanted openings thereof. The first end 16A, 17A of the first 16 and second plate 17 define the inlet for the housing 18 through which the mandrel 10 enters the housing 18.

[0233] Each mandrel 10 is carried along the movement trajectory M between a receiving zone 202, in which the mandrel 10 receives an article 1 from the transfer carousel 103, an abutment zone 203, in which the mandrel 10 abuts a blank 7 supplied by the feeding device 30 in a first abutment position R1, a forming zone 204, in which the blank 7 is folded on the mandrel so as to form a box 2 containing the article 1, an unloading zone 205, in which the box 2 containing the article 1 is deposited on the outlet carousel 6 and, finally, a return zone 206 in which the mandrel 10 is returned to the receiving zone 202. From the outlet carousel 6, the box 2 is then deposited on the evacuation belt 8 to be transported to the subsequent processing stations.

[0234] The blank 7, better visible in FIG. 9, is made of cardboard with a thickness comprised between 0.4 and 0.8 mm, in this case about 0.5 mm, and is suitably shaped to form a box 2 when folded around the mandrel 10. For this purpose, folding lines 70 are obtained on the blank 7 that divide the blank 7 into a plurality of panels 71 intended to form, alone or in combination with each other, the different faces of the box 2. The folding lines 70 are preferably creases and each pair of adjacent panels 71 is oscillatable around a respective folding line 70 that separates them. In particular, as better visible in FIG. 9, an intermediate panel 7C is identified in the blank 7 that is intended to be abutted as first by the mandrel 10, as well as a first and a second panel 7A, 7B respectively extended on two opposed sides of the intermediate panel 7C, and separated therefrom by respective folding lines 70, a third panel 7D positioned so that the first panel 7A is interposed between the third panel 7D and the intermediate panel 7C and a closing panel 7E positioned so that the second panel 7B is interposed between the closing panel 7E and the intermediate panel 7C. The first and second panels 7A, 7B are intended to form two opposed faces of the box 2. The first and second panels 7A, 7B are intended to be folded on the mandrel 10 on opposite sides with respect to the advancement plane 200, as better clarified below. On an edge portion of the third panel 7D it is provided to apply glue for the closure of the box 2.

[0235] The mandrel 10 comprises a first unit 11 and a second unit 12, which are distinct and separated from each other, both mounted on an arm not extended radially by the movement carousel 3 and passing below a fixed work surface 9 of the packaging unit 100.

[0236] The first unit 11 and the second unit 12 are positioned so as to define an accommodation seat 13 for an article 1 to be transported. Advantageously, the first 11 and the second unit 12 are displaceable with respect to each other so as to define an accommodation seat 13 for the articles 1 with variable dimensions.

[0237] The mandrel 10 further comprises a first abutment surface 10A defined as the surface of the mandrel 10 intended to be the first to abut the blank 7 when the latter is positioned in the movement trajectory M. The first abutment surface 10a is the surface of the mandrel 10 provided in the further advanced position along the movement trajectory M.

[0238] The folding device 20, better visible in FIGS. 6-8, comprises a first folding element 21 and a second folding element 22 which are arranged to abut respectively the first panel 7A and the second panel 7B of the blank 7. The first and second folding elements 21, 22 are positioned so as to respectively abut a first and a second panel of the blank 7 which are positioned on opposite sides with respect to the advancement plane 200 defined by the mandrel 10.

[0239] The first folding element 21 comprises a folding portion 21A shaped to interact with the blank 7 and a movement arm 21B extending from the folding portion 21A and intended to be coupled to the actuation device 40 to actuate the first folding element 21.

[0240] Similarly, the second folding element 22 comprises a second folding portion 22A shaped to interact with the blank 7 and a second movement arm 22B extending from the folding portion 22A and intended to be coupled to the actuation device 40 to actuate the second folding element 22.

[0241] The folding portion 21A, 22A is made integral with the respective movement arm 21B, 22B.

[0242] The actuation device 40 comprises an actuation motor 41 coupled to the first folding element 21 through a first movement member 21D for transmitting motion from the actuation motor 40 to the first folding element 21, and a second transmission element 42 coupled to the second folding element 22 through a second movement member 22D. The transmission element 42 is operatively interposed between the actuation motor 41 and the second movement arm 22B so as to transmit motion from the actuation motor 41 to the second movement arm 22B. The first and second movement members 21D, 22D comprise a plurality of mutually hinged levers to form an articulated polygon movement member.

[0243] The first 21 and the second folding element 22 are associated respectively with the first 16 and the second guide plate 17. This measure increases the stability of the folding device 20 and optimises the folding of the box avoiding unwanted openings.

[0244] In a version not shown there is provided a first actuation motor for actuating the first folding element and a second actuation motor for actuating the second folding element.

[0245] Each folding portion 21A, 22A defines a respective first impact surface 21C, 22C of the blank 7 against the respective folding element 21, 22. The first impact surface 21C, 22C is the surface of each folding element 21, 22 which abuts the blank 7 as first when positioned on the movement trajectory M.

[0246] The first impact surface 21C, 22C has a rounded shape, convex towards the blank 7 with a curvature such as to form with the blank an angle of about 45. The first impact surface 21C, 22C is made of low friction coefficient material, usually plastic, or metallic material. In some versions the first impact surface 21C, 22C is made of stainless steel.

[0247] Each folding element 21, 22 comprises an adjustment element, not visible in the figures, for adjusting the extension of the first impact surface 21C, 22C along an adjustment direction transversal to the movement trajectory M to vary the portion pf the blank 7 which is abutted by the first impact surface 21C, 22C.

[0248] The actuation device 40 is configured to move the folding device 20 alternately in a direction concordant to the movement trajectory M and in a direction opposite to the movement trajectory M.

[0249] In particular, as better schematized in FIGS. 10A and 10B, the folding device 20 is moved along the folding stroke P in a direction concordant to the movement trajectory M with an accompanying speed Va to fold the blank 7 on the mandrel 10 and along the folding stroke P in a direction contrary to the movement trajectory M with a return speed VR so as to be brought towards the mandrel 10.

[0250] The folding device 20 is movable along the folding stroke P between a first position P1 which corresponds to the further backward position of the folding device 20 along the movement trajectory M and a second position P2 which corresponds to the most advanced position of the folding device 20 along the movement trajectory M. The second position P2 is provided near the first end 16a, 17A of the first 16 and the second plate 17.

[0251] The actuation device 40 moves the folding device 20 from the second position P2 to the first position P1 with a return speed VR to bring it towards the mandrel 10 and moves the folding device 20 from the second position P2 to the first position P1 with an accompanying speed concordant to the movement speed VM to fold the blank 7.

[0252] In particular, the actuation device 40 moves the folding device 20 in succession along a first portion PA of the folding stroke P between the first position P1 and an abutment position R2 and along a second portion PB of the folding stroke P between the abutment position R2 and the second position P2. In the first portion PA the folding device 20 is spaced apart from the mandrel 10 and from the blank 7, while in the second portion PB the folding device 20 is in contact with the blank 7.

[0253] In the first portion PA, the distance between the folding device 20 and the mandrel 10 is progressively reduced up to the abutment position R2 in which the folding device 20 abuts the blank 7. The abutment position R2 is provided downstream of the first abutment position R1. In the second portion of the folding stroke PB the folding device is at least partially overlapped on the mandrel 10.

[0254] In the first position P1, which is provided downstream of the first abutment position R1, the folding device 20 is spaced apart from the mandrel 10 and from the blank 7 and positioned at an advanced position with respect to the mandrel 10. In the second position P2 the folding device is overlapped on the mandrel 10.

[0255] By moving the folding device 20 along the folding stroke P in a direction concordant to the movement trajectory M and in a direction contrary to the movement trajectory M, it is possible to bring the folding device 20 to subsequently interact with each mandrel 10 of the plurality of mandrels 10.

[0256] In a version not shown, the second movement arm comprises two arm portions internally provided with a serration and mutually spaced apart so as to define a housing seat for a rotatable toothed wheel. The teeth of the toothed wheel are shaped to couple with the serration of the arm portions, so that, following the rotation of the toothed wheel, a displacement of the second movement arm and, therefore, of the second folding device are generated.

[0257] The packaging unit 201 further comprises a retaining device 60, shown in greater detail in FIG. 11, displaceable along an actuation trajectory between an operating position E1 in which the retaining device 60 is approached to the first abutment surface 10A of the mandrel to retain the blank 7 against the first abutment surface 10A and a non-operating position not shown in the Figures in which the retaining device 60 is spaced apart from the first abutment surface 10A.

[0258] The retaining device 60 comprises a lamina 61 having a retaining surface 62 shaped so as to couple with shape coupling with the first abutment surface 10A.

[0259] The retaining device 60 is positioned so as to be interposed, in the operating position E1, between the first folding element 21 and the second folding element 22 to retain the intermediate panel 7C of the blank 7. The lamina 61 is configured to couple to the intermediate panel 7C.

[0260] The packaging unit 201 further comprises an actuation member 63 intended to move the retaining device 60 between the operating position E1 and the non-operating position.

[0261] The retaining device 60 is operatively associated with the mandrel 10 so as to be carried, via the movement device 40, together with the mandrel 10, along the movement trajectory M. The retaining device 60 is also movable with respect to the mandrel 10 in order to be displaced between the operating position E1 and the non-operating position.

[0262] As best shown in FIG. 12, in the version shown, the lamina 61 is constrained at a first end 61a thereof to a support element 64 interposed between the lamina 61 and the actuation element 63 so as to be displaced between the operating position E1 and the non-operating position along an actuation trajectory having a transverse component Tx transverse to the movement trajectory M and a thrust component Ty parallel to the movement trajectory M. The transverse component Tx and the thrust component Ty are perpendicular to each other and parallel to the advancement plane 200.

[0263] The operation of the packaging unit 100 is now explained. An article 1 is deposited on a mandrel 10 at the receiving zone 202 and moved together with the mandrel 10 along the movement trajectory M. The mandrel 10 is moved along the movement trajectory M at a movement speed VM having modulus M2.

[0264] The feeding device 30 feeds a blank 7 towards the movement carousel 3, positioning it in a feeding position A1 provided along the movement trajectory M in an advanced position with respect to the mandrel 10 and moves the blank 7 along the movement trajectory M for a feeding stroke comprised between the feeding position A1 and a release position R3.

[0265] The mandrel 10 in movement along the trajectory M approaches the blank 7 until, in the first abutment position R1, the first abutment surface 10A of the mandrel 10 abuts the blank 7.

[0266] Subsequently, the mandrel 10 moves along the movement trajectory M together with the blank 7 and the feeding device 30 up to a release position R3 in which the feeding device 30 releases the blank 7. From the release position R3 the feeding device 30 is moved away from the movement trajectory M. From the release position R3 the mandrel 10 transports the blank 7 up to the abutment position R2 in which the folding device 20 abuts the blank 7. From the abutment position R2 to the second position P2 the mandrel 10 and the folding device 20 both move along the movement trajectory M folding the blank 7 around the mandrel. In the second position P2 the folding device 20 stops while the mandrel 10 continues its movement along the movement trajectory M coming out of the folding device 20 to enter the housing 18 defined between the first guide plate 16 and the second guide plate 17.

[0267] In the abutment position R2 the folding device 20 is moving along the folding stroke P at the accompanying speed Va which is parallel to the movement speed VM and has modulus M1 lower than the modulus M2 of the movement speed VM.

[0268] It is noted that when the folding device 20 abuts the blank 7, the folding device 20 is moved in a manner concordant to the mandrel 10 even if at a speed with a lower modulus and this prevents there being kickbacks on the blank 7 and sudden strokes being imparted on the same.

[0269] The folding device 20 abuts the blank 7 in the abutment position R2 and accompanies the mandrel up to the second position P2, that is up to the inlet of the housing 18.

[0270] Since the accompanying speed Va of the folding device 20 has a modulus M1 lower than the further modulus M2 of the movement speed VM, in the second portion PB of the folding stroke P a relative motion between the folding device 20 and the mandrel 10 and, therefore, between the folding device 20 and the blank 7 is generated since the latter is integral with the mandrel 10.

[0271] In other words, since in the second folding stroke PB the folding device 20 is slower than the mandrel 10 it progressively slides along the blank 7 in the direction opposed to the movement trajectory M, effectively folding the blank 7 around the mandrel 10.

[0272] Between the first abutment position R1 and the release position R3, on the movement trajectory M a retaining position R4 is defined in which the retaining device 60 is positioned in the operating position E1 and engages the intermediate panel 7C of the blank 7 to retain it on the mandrel 10.

[0273] The actuation member 63 is configured to displace the retaining device 60 towards the blank 7 so as to bring it against the intermediate panel 7C of the blank 7.

[0274] The presence of the retaining device 60 makes it possible to make the positioning of the blank on the mandrel 10 more precise so as to fold the blank around the mandrel in an extremely precise manner.

[0275] Between the abutment position R2 and the second position P2 a detachment position R5 can be provided in which the retaining device 60 moves away from the mandrel 10 and then from the blank 7 returning to the non-operating position. Since said detachment position R5 is provided downstream of the abutment position R2, when the retaining device 60 detaches itself from the blank 7, the latter is retained on the mandrel 10 in addition to the friction force generated by the movement of the mandrel 10 itself, also by the folding device 20 which has already engaged the blank 7 and which exerts a thrust force on the blank 7 to fold it on the mandrel 10. The blank 7 is therefore interposed between the mandrel 10 and the folding device 20. Thus, the blank 7 does not displace itself from the desired position.

[0276] Conveniently, by acting on the actuation element 63, it is possible to vary the duration of the retaining phase, i.e. the distance between the retention position R4 and the detachment position R5, based, for example, on the characteristics of the blank 7. In one embodiment, the retaining device 60 is held in the operating position E1 until the end of the forming step for forming the box 2.

[0277] In the version shown, the mandrel 10 and/or the folding device 20 are moved at respective speeds such as to define a relative speed comprised between about 0.1 and 1 m/s.

[0278] These values allow to effectively fold a blank around the mandrel avoiding damages to the blank and avoiding unwanted splashes of glue.

[0279] In the version shown, the release position R3 is provided upstream of the abutment position R2, however in other versions it may be provided downstream of the abutment position R2.

[0280] In other versions, moreover, the retaining device 60 may not be provided. This version of the packaging unit is particularly compact, moreover the absence of the retaining device and of the relative actuation members reduces the weight of the packaging unit simplifying its operation.

[0281] An alternative version of the packaging unit is shown in FIGS. 13, 14A, 14B. This version of the transfer unit is completely similar to that described above, therefore, corresponding parts will be indicated with the same numerical references and will not be described in detail. Such a packaging unit differs from the one described above substantially in that it lacks the retaining device. This implies a different succession of the operations for transferring the blank 7, as better clarified below.

[0282] The operation of the aforesaid variant of the packaging unit 100 is now explained. An article 1 is deposited on a mandrel 10 at the receiving zone 202 and moved together with the mandrel 10 along the movement trajectory M. The mandrel 10 is moved along the movement trajectory M at a movement speed VM having modulus M2.

[0283] The feeding device 30 feeds a blank 7 towards the movement carousel 3, positioning it in a feeding position A1 provided along the movement trajectory M in an advanced position with respect to the mandrel 10 and moves the blank 7 for a feeding stroke of the movement trajectory M.

[0284] The mandrel 10 in movement along the trajectory M approaches the blank 7 until, in the first abutment position R1, the first abutment surface 10A of the mandrel 10 abuts the blank 7. Subsequently, the mandrel 10 moves along the feeding stroke together with the blank 7 and the feeding device 30 up to a release position R3 in which the feeding device 30 releases the blank 7. From the release position R3 the mandrel 10 transports the blank 7 up to the abutment position R2 where the folding device 20 abuts the blank 7. From the abutment position R2 to the second position P2 the mandrel 10 and the folding device 20 both move along the movement trajectory M folding the blank 7 around the mandrel 10. In the second position P2 the folding device 20 stops while the mandrel 10 continues its movement along the movement trajectory M coming out of the folding device 20 to enter the housing 18 defined between the first guide plate 16 and the second guide plate 17.

[0285] The blank 7 is abutted by the folding device 20 after having been released by the feeding device 30 in the release position R3. Between the release position R3 and the abutment position R2 the blank 7 is transported only by the mandrel 10. There are no further devices intended to keep the blank 7 on the mandrel 10. The blank 7 is kept on the mandrel 10 by the friction generated by the movement of the mandrel 10 along the movement trajectory M.

[0286] The number of components of the packaging unit 100 placed near the blank 7 is extremely small, therefore the packaging unit 100 is particularly compact and of reduced weight, therefore more easily actuatable. This also implies that the risk of interferences between the different components of the packaging unit 100 is extremely low.

[0287] In addition, the folding device can be freely moved towards the mandrel to abut the blank.

[0288] Furthermore, in the portion of movement trajectory between release position R3 and abutment position R2, the blank 7 is kept on the mandrel 10 by the friction generated by the movement of the mandrel 10 itself. Therefore, due to the high movement speeds of the mandrel 10, the risk of unwanted displacements of the blank 7 is reduced.

[0289] In the abutment position R2 the folding device 20 is moving along the folding stroke P at the accompanying speed Va which is parallel to the movement speed VM and has modulus M1 lower than the modulus M2 of the movement speed VM.

[0290] Therefore, when the folding device 20 abuts the blank 7, the folding device 20 is moved in a manner concordant to the mandrel 10 even if at a speed with a lower modulus and this prevents there being kickbacks on the blank 7 and sudden strokes being imparted on the same. This prevents unwanted displacements of the blank 7 from the desired position on the mandrel 10.

[0291] The actuation device 40 moves the first 21 and the second folding element 22 so that they abut the blank 7 almost simultaneously. In other words, both the first 7A and the second panel 7B are abutted in the abutment position R2. This avoids slippages of the blank 7 with respect to the desired position.

[0292] The first folding element 21 and the second folding element 22 are positioned symmetrically with respect to the advancement plane 200, so as to avoid unwanted displacements of the blank 7 from the desired position.

[0293] The folding device 20 abuts the blank 7 in the abutment position R2 and accompanies the mandrel up to the second position P2, that is up to the inlet of the housing 18.

[0294] Since the accompanying speed Va of the folding device 20 has a modulus M1 lower than the further modulus M2 of the movement speed VM, in the second portion PB of the folding stroke P a relative motion between the folding device 20 and the mandrel 10 and, therefore, between the folding device 20 and the blank 7 is generated since the latter is integral with the mandrel 10.

[0295] In other words, since in the second folding stroke PB the folding device 20 is slower than the mandrel 10 it progressively slides along the blank 7 in the direction opposed to the movement trajectory M, effectively folding the blank 7 around the mandrel 10.

[0296] In the version shown, the mandrel 10 and/or the folding device 20 are moved at respective speeds such as to define a relative speed comprised between about 0.1 and 1 m/s.

[0297] Such values allow to effectively fold a blank 7 around the mandrel 10 avoiding damages to the blank 7 and avoiding unwanted splashes of glue.

[0298] In an alternative version not shown, the folding device 20 abuts the blank 7 before the mandrel 10, that is, the abutment position R2 is provided upstream of the first abutment position R1. In this case the release position R3 is provided downstream of the abutment position R2 and upstream of the first abutment position R1, between the release position R3 and the abutment position R2 the blank 7 is retained only by the folding device 20 and kept thereon by effect of friction.

[0299] Therefore, a packaging unit is obtained that allows the blank to be folded precisely on a mandrel.