WO2008122623A2

WO2008122623A2 - Folding unit for producing sealed packages of pourable food products

Info

Publication number: WO2008122623A2
Application number: PCT/EP2008/054122
Authority: WO
Inventors: Davide Sabbadini; Roberto Ansaloni
Original assignee: Tetra Laval Holdings & Finance S.A.
Priority date: 2007-04-05
Filing date: 2008-04-04
Publication date: 2008-10-16
Also published as: CN101652288A; JP5542654B2; JP2010523412A; ITTO20070243A1; WO2008122623A3; HK1141262A1; CN101652288B

Abstract

A folding unit (1) for packaging machines for packaging pourable food products, having : conveying means (40) for feeding along a forming path (B) at least one sealed pack (3) containing a pourable food product and having a portion (6, 7) to be folded to form a finished package (2); and first folding means (50; 65) having at least one first interacting member (51; 66, 67) movable back and forth between a work position, in which it cooperates with the pack (3) along the path (B) to perform a first forming operation on the pack, and a rest position, in which it is detached from the pack (3); the first interacting member (51; 66, 67) being movable along a first trajectory intersecting the path (B) at a first station (B3; B5) of the path (B), where the first forming operation is performed; the first folding means (50; 65) having at least one first control member (52; 68) rotating about a first axis (D, F), and a first transmission (53; 70) functionally connecting the first control member (52; 68) and the first interacting member (51; 66, 67); the first transmission (53; 70), in use, converting one-way rotation of the first control member (52; 68) into a back-and- forth movement of the first interacting member (51; 66, 67) between the work position and the rest position.

Description

FOLDING UNIT FOR PRODUCING SEALED PACKAGES OF POURABLE FOOD PRODUCTS

TECHNICAL FIELD The present invention relates to a folding unit for producing sealed packages of pourable food products from a tube of packaging material.

It should be pointed out that, in the following description and Claims, the term "package" is used in its widest sense to indicate any type of container for packaging liquid or pourable food products, and therefore includes, not only the packs of multilayer sheet material and similar referred to herein by way of example, but also glass or plastic bottles, cans, etc. BACKGROUND ART

As is known, many pourable food products, such as fruit juice, UHT (ultra- high-temperature treated) milk, wine, tomato sauce, etc., are sold in packages made of sterilized packaging material.

A typical example of this type of package is the parallelepiped-shaped package for liquid or pourable food products known as Tetra Brik Aseptic (registered trademark), which is made by folding and sealing laminated strip packaging material. The packaging material has a multilayer structure comprising a layer of base material, e.g. paper, covered on both sides with layers of heat-seal plastic material, e.g. polyethylene. In the case of aseptic packages for long-storage products, such as UHT milk, the packaging material comprises a layer of oxygen- barrier material, e.g. aluminium foil, which is superimposed on a layer of heat-seal plastic material, and is in turn covered with another layer of heat-seal plastic material eventually forming the inner face of the package contacting the food product.

As is known, packages of this sort are produced on fully automatic packaging lines, on which a continuous tube is formed from the web-fed packaging material; the web of packaging material is sterilized, e.g. by applying a chemical sterilizing agent such as hydrogen peroxide, which, once sterilization is completed, is removed, e.g. evaporated by heating, from the surfaces of the packaging material; and the sterilized web of packaging material is maintained in a closed, sterile environment, and is folded and sealed longitudinally to form a vertical tube.

The tube is filled with the sterilized or sterile-processed food product, and is sealed and cut along equally spaced cross sections to form pillow packs.

The pillow packs are then folded mechanically on a folding unit into finished packages, e.g. substantially parallelepiped-shaped packages or so-called "gable-top" packages known by the trade name Tetra Rex (registered trademark).

More specifically, the pillow packs comprise a parallelepiped-shaped main portion; and opposite, respectively top and bottom, end portions tapering from the main portion to respective sealing lines crosswise to the pack. Each end portion has substantially triangular flaps projecting from opposite sides of the main portion; and a low rectangular tab projecting from the relative sealing line.

Packaging machines of the above type are known, on which the pillow packs are folded into gable-top packages by automatic folding units.

The folding units substantially comprise a first and second folding station for performing a first and second folding operation on the packs respectively; and a trolley for transferring the packs from the first to the second folding station.

More specifically, the first folding station comprises a first conveyor rotating about a first axis to feed each pack along an arc-shaped path.

The first conveyor comprises first clamping means, which clamp a first end portion of each pack as it is moved along, while allowing access to a second end portion opposite the first end portion.

The first folding station also comprises a first folding assembly for folding the second end portion of each pack as it is moved along by the first conveyor.

Similarly, the second folding station comprises a second conveyor rotating about a second axis to feed each pack along an arc-shaped path, and comprising second clamping means, which clamp the second end portion of each pack as it is moved along.

The second folding station also comprises a second folding assembly for folding the first end portion of each pack as it is moved along by the second conveyor.

More specifically, the first folding assembly is located radially outwards of the first conveyor with respect to the first axis; and, similarly, the second folding assembly is located radially outwards of the second conveyor with respect to the second axis.

The first and second folding assembly each comprise an interacting surface movable cyclically between a work position, in which it interacts with and folds the relative end portion of the pack, and a rest position, in which it is detached from the relative end portion of the pack. The first and second folding assembly each comprise a drive member connected functionally by a transmission to the relative interacting surface to move it back and forth between the rest position and the work position.

More specifically, when each drive member rotates in a first direction, the relative interacting surface moves from the rest position to the work position; and, conversely, when each drive member rotates in a second direction, opposite the first direction, the relative interacting surface moves from the work position to the rest position.

Though reliable and efficient, folding units of the above type still leave room for improvement. That is, in actual use, each drive member performs a work cycle comprising a number of alternating rotations in the first and second direction, and which must be performed rapidly for the folding unit to operate at a high output rate.

As a result, the drive members and the folding unit are subjected, in use, to fatigue stress that limits the output rate and the working life of the folding unit.

High torques must also be transmitted to the interacting surfaces to accelerate and decelerate them rapidly as they move between the respective work and rest positions. For this reason, each transmission must necessarily comprise a reducer, which receives a given torque from the relative drive member, multiplies it, and transmits it to a mechanism connecting the reducer functionally to the relative interacting surface.

Being subjected periodically to torques in alternating directions, the reducers and mechanisms are also subject to fatigue and wear that limit the output rate and the working life of the folding unit.

Finally, the trolley is operated by a relative drive member by means of a drive belt, and, in use, performs a number of back and forth strokes between the first and second folding station. More specifically, during the forward stroke, the trolley transfers a pack from the first to the second folding station, and, during the return stroke, moves from the second to the first folding station.

In use, the drive member of the trolley therefore also performs a number of alternating rotations in a first and second direction, and which further stress the folding unit.

DISCLOSURE OF INVENTION

It is an object of the present invention to provide a folding unit for producing sealed packages of pourable food products, and designed to provide a straightforward, low-cost solution to at least one of the aforementioned drawbacks typically associated with known units.

According to the present invention, there is provided a folding unit for producing sealed packages of pourable food products, as defined in Claim 1.

BRIEF DESCRIPTION OF THE DRAWINGS A preferred, non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:

Figure 1 shows a front view of a folding unit, for pourable food product packaging machines, in accordance with the present invention;

Figure 2 shows a rear view of the Figure 1 folding unit;

Figure 3 shows a larger-scale front view of a first assembly of the Figure 1 unit;

Figure 4 shows a larger-scale view in perspective, with parts removed for clarity, of a second assembly of the Figure 1 unit;

Figures 5 and 6 show a larger-scale view in perspective and a larger-scale front view, respectively, of a first folding device of the Figure 1 unit;

Figures 7 and 8 show a larger-scale view in perspective and a larger-scale, partly sectioned top plan view, respectively, of a second folding device of the Figure 1 unit;

Figures 9 to 14 show schematic front views of a preferred folding sequence performed on a pillow pack by the Figure 1 unit to form a parallelepiped-shaped package.

BEST MODE FOR CARRYING OUT THE INVENTION Number 1 in Figure 1 indicates as a whole a folding unit for a packaging machine for continuously producing sealed, parallelepiped-shaped packages 2 (Figure 14) of a pourable food product, such as pasteurized or UHT milk, fruit juice, wine, etc., from a known tube, not shown, of packaging material.

More specifically, the tube is formed in known manner upstream from folding unit 1 by longitudinally folding and sealing a web of heat-seal sheet material, and is filled with the sterilized or sterile-processed food product.

The tube of packaging material is then filled with the food product for packaging, and is sealed and cut along equally spaced cross sections to form a number of pillow packs 3 (Figure 9), which are then sent to unit 1 where they are folded mechanically into respective packages 2.

With reference to Figure 9, each pack 3 has an axis A, and comprises a parallelepiped-shaped main portion 4; and opposite, respectively top and bottom, end portions 6, 7 tapering from portion 4 to respective sealing lines 8, 9, crosswise to axis A, of pack 3.

More specifically, portion 4 of each pack 3 is bounded laterally by two flat rectangular walls 10 parallel to each other, to axis A, and to sealing lines 8, 9; and by two flat rectangular walls 11 extending between walls 10. Each portion 6, 7 is defined by two walls 12 substantially in the form of an isosceles trapezium, sloping slightly towards each other with respect to a plane perpendicular to axis A, and having minor edges defined by respective end edges of walls 10 of portion 4, and major edges joined to each other by the respective sealing line 8, 9. For each portion 6, 7, each pack 3 has an elongated, substantially rectangular tab 13, 14 projecting from respective sealing line 8, 9; and two substantially triangular flaps 15, 16 projecting laterally from opposite sides of portion 4 and defined by end portions of relative walls 12.

To form a package 2, unit 1 presses portions 6, 7 of pack 3 towards each other, while at the same time folding respective tabs 13, 14 onto portions 6, 7; folds and seals flaps 15 of portion 6 onto relative walls 12; and folds and seals flaps 16 of portion 7 onto respective walls 11 of portion 4.

More specifically, flaps 15, 16 are folded with respect to walls 12, 11 about respective fold lines 17, 18 coincident with respective edges between walls 11 and portions 6, 7.

Unit 1 (Figure 1) comprises a known supporting frame 20, of which only a vertical wall 21 is shown; a main conveyor 40 fitted to wall 21 of frame 20 to rotate about an axis C and feed a succession of packs 3 in steps along an arc-shaped forming path B; and a number of pairs of rails 22, 23, 24, 25, 26, 27 (Figure 4) and 28 (Figure 1) fitted in fixed positions to frame 20 and cooperating with packs 3 along path B to perform a number of folding operations on the packs, as described in detail below. Unit 1 also comprises a folding device 50 (shown in detail in Figures 5 and

6) fitted to frame 20 and having an interacting surface 51, which interacts with portions 6 of packs 3 travelling along path B to perform a folding operation on the packs; a heating device 60 fitted to frame 20 to heat the unfolded flaps 15, 16 of each pack 3 travelling along path B, preparatory to heat sealing flaps 15, 16 to respective walls 12, 11; and a final folding device 65 (shown in more detail in Figures 7 and 8) fitted to frame 20 and having an interacting surface 66 and a pair of interacting surfaces 67 for pressing flaps 15, 16, respectively, of each pack 3 travelling along path B onto respective walls 12, 11, as flaps 15, 16 cool.

More specifically (Figure 1), path B extends from a loading station B₁, where conveyor 40 receives each pack 3 from an input conveyor 80, to an unloading station B₂, where conveyor 40 unloads a relative package 2 onto an output conveyor 90.

From station Bi towards station B₂, path B also comprises:

- a first portion, along which rails 22, 24, 25 interact with each pack 3 to convert it from a pillow configuration (Figure 9) to a configuration (Figure 10) in which portions 6, 7 are pressed towards each other to fold walls 12 of portions 6, 7 into a position perpendicular to axis A, and to fold tabs 13, 14 onto respective walls 12;

- a station B3 where interacting surface 51 of folding device 50 interacts with each pack 3 to fold flaps 15 about fold lines 17 into a position parallel to axis

A, and to fold flaps 16 about fold lines 18 into a position sloping slightly with respect to axis A and towards portion 6 (Figure 11); and

- a second portion, along which rails 23, 24, 25 interact with each pack 3 to convert it from the Figure 11 configuration to a configuration in which flaps 15, 16 slope forty- five degrees with respect to relative walls 12, 11, and extend from respective fold lines 17, 18 towards axis A and away from axis A respectively.

From the second portion to station B₂, path B also comprises: - a station B₄ where heating device 60 heats flaps 15, 16 of each pack 3, preparatory to heat sealing them onto respective walls 12, 11;

- a third portion, along which rails 26, 27 fold flaps 15, 16 of each pack 3 to convert it to the Figure 13 configuration, in which flaps 15, 16 slope roughly ten degrees with respect to walls 12, 11, and extend from fold lines 17, 18 towards axis A and away from axis A respectively;

- a station B5 where surfaces 66 and 67 of folding device 65 fold flaps 15, 16 of each pack 3 onto relative walls 12, 11 to complete formation of package 2 (Figure 14); and

- a fourth portion terminating at station B₂, and along which rails 28 keep flaps 15 pressed onto walls 12 to prevent accidental detachment of the flaps as they cool.

In the example shown, the angular distance covered by conveyor 40 between stations Bl and B3, stations B3 and B4, and stations B4 and B5 is seventy- two degrees. More specifically, conveyor 40 comprises a hub 41 rotating about axis C; and a number of - in the example shown, five - clamping devices 42 for gripping respective packs 3 at station Bi, and feeding them along path B to station B₂, so packs 3 interact with rails 22, 23, 24, 25, 26, 27, 28, folding devices 50, 65, and heating device 60. More specifically, hub 41 is rotated in steps about axis C by a motor 43 only shown in Figure 2.

Clamping devices 42 are equally spaced angularly about axis C, project from hub 41, on the opposite side to axis C and in respective radial directions with respect to axis C, and are therefore angularly integral with hub 41.

Each clamping device 42 comprises two members 44 projecting from hub 41.

More specifically, each member 44 defines a respective flat surface 45 elongated radially with respect to axis C; and members 44 are positioned with surfaces 45 facing each other.

Surfaces 45 cooperate with respective walls 10 of relative pack 3, so as to guide pack 3 along path B.

Rails 22, 23, 24, 25 and 26, 27 (Figure 4) are arc-shaped and fitted to a structure 29 (only shown partly in Figure 4) fixed to wall 21 of frame 20.

More specifically, structure 29 substantially comprises two parallel walls (only one shown in Figure 4) connected to each other a given distance apart to define a gap housing rails 22, 23, 24, 25 and 26, 27.

One of rails 22, 23, 24, 25 and 26, 27 is fixed to a first wall of structure 29, and the other of rails 22, 23, 24, 25 and 26, 27 is fixed to a second wall of structure 29.

Rails 22 are fixed to structure 29 at such a distance apart that corresponding points of rails 22 are the same radial distance from axis C.

Similarly, corresponding points of rails 23, 24, 25, 26 and 27, 28 are the same radial distance from axis C, and are spaced apart in a direction parallel to axis C.

Each rail 22, 23 is further away from axis C than a corresponding rail 24.

Each rail 24 is further away from axis C than a corresponding rail 25.

Rails 22, 23 cooperate with portion 6 of each pack 3. More specifically, rails 23 cooperate with portion 6 after rails 22.

Rails 24, 25 cooperate with walls 11 and portion 7 of each pack 3.

Each rail 22 comprises a wall lying in a plane perpendicular to axis C, and defining a supporting surface 30 on the axis C side. Rails 23, 24 are defined by respective walls extending radially with respect to axis C. More specifically, surfaces 30 extend perpendicularly to the planes of rails 23, 24.

Each rail 25 comprises a wall 31 substantially parallel to rails 24; and a wall 33 projecting from wall 31 and substantially parallel to surface 30.

More specifically, walls 33 extend from respective ends 32 of rails 25 at station B₁, and along an arc equal to the arc travelled by conveyor 40 to guide the packs from station Bi to station B₃.

Walls 31 are positioned facing each other, and each wall 33 extends from a radially outer surface of relative wall 31 and on the opposite side to the other wall 31.

Rails 22, 24 have respective first ends 34, 35 at station B₁; and respective second ends 36, 37 opposite first ends 34, 35. More specifically, ends 36 of rails 22 are located at station B₃. Rails 23 have respective first ends 39 located at station B3 and facing corresponding ends 36 of rails 22; and respective second ends 46 opposite ends 39.

Rails 25 also have respective ends 38 opposite ends 32.

The radial distance, with respect to axis C, between rails 22, 25 decreases from respective ends 34, 32 to station B₃. And similarly, the radial distance, with respect to axis C, between rails 23, 25 decreases from station B3 to respective ends 46, 38.

Rails 22, 23 are separated in a direction parallel to axis C to permit passage of interacting surface 51 at station B₃.

Rails 26, 27 are fixed to structure 29 so as to be spaced apart angularly from rails 23, 24, 25, and located downstream from rails 23, 24, 25 along path B in the travelling direction of packs 3.

More specifically, rails 26, 27 have respective first ends 47, 48; and respective second ends 49, 58 opposite ends 47, 48. More specifically, ends 49, 58 are located at station B5 and therefore downstream from ends 47, 48 in the travelling direction of packs 3 along path B.

Rails 26, 27 are defined by respective walls lying in planes substantially radial with respect to axis C. With reference to axis C, each rail 26 is located radially outwards with respect to a corresponding rail 27.

Rails 26 converge slightly along respective initial portions adjacent to respective ends 47; and, similarly, rails 27 converge slightly along respective initial portions adjacent to respective ends 48. Rails 28 are fitted in fixed positions to unit 1, cooperate with flaps 15 along the portion of path B extending from station B₅ to station B₂, and extend at such a distance from axis C as to prevent detachment of flaps 15 from walls 12.

More specifically, rails 28 are L-shaped, and each comprise a first wall (not shown in Figure 1) cooperating with a respective flap 15 of pack 3; and a second wall 59 perpendicular to the first wall and cooperating with a portion of relative wall 11 adjacent to flap 15.

The first walls of rails 28 extend at the same radial distance from axis C.

Folding device 50 is fixed to wall 21 so that interacting surface 51 interacts with each pack 3 at station B₃ of path B. More specifically, folding device 50 is fixed to wall 21 on the opposite side of hub 41 to axis C.

With reference to Figures 5 and 6, folding device 50 comprises a pulley 52 rotating about an axis D parallel to axis C; and a transmission 53 for transmitting motion from pulley 52 to interacting surface 51. More specifically, transmission 53 comprises a shaft 54 coaxial with pulley

52; a cam 55 angularly integral with shaft 54; and a cam follower 56 (only shown in Figure 6) engaging cam 55 and integral with interacting surface 51.

More specifically, cam follower 56 is integral with a structure 57 extending perpendicular to axis D and fitted at one end with interacting surface 51.

Shaft 54 extends through wall 21, is connected at a first axial end to pulley 52, and is connected to cam 55 at the opposite end to the first end.

More specifically, cam 55 defines a groove 63 extending eccentrically about axis D and housing cam follower 56.

Transmission 53 advantageously converts a full one-way turn of shaft 54 about axis D into a back-and-forth translatory movement of structure 57 and interacting surface 51 along an axis E perpendicular to axis C and, more specifically, intersecting path B at station B₃. Said back-and-forth translatory movement extends between a work position, in which interacting surface 51 exerts pressure on walls 12 of portion 6 of each pack 3 folded by rails 22, 24, 26 into the Figure 10 configuration, to convert pack 3 into the Figure 11 configuration; and a rest position, in which interacting surface 51 is detached from pack 3 to allow travel of the pack along path B. Groove 63 is so shaped that, for each full turn of cam 55 about axis D, cam follower 56 moves interacting surface 51 first from the work position to the rest position, and then from the rest position to the work position.

As shown in Figure 1, folding device 65 is fixed to wall 21 so that surfaces 66, 67 interact with each pack 3 at station B₅ of path B. Folding device 65 is also fixed to wall 21 to extend on the opposite side of hub 41 to axis C.

With reference to Figures 7 and 8, folding device 65 comprises a pulley 68 rotating about an axis F parallel to axis C; a shaft 69 (only shown in Figure 8) angularly integral with pulley 68 and connected functionally to interacting surfaces 66, 67; and a transmission 70 for transmitting motion from pulley 68 to interacting surfaces 66, 67.

Transmission 70 advantageously converts a full one-way turn of pulley 68 about axis F into a back-and-forth translatory movement of interacting surface 66 between a work position, in which it presses flaps 15 of each pack 3 onto walls 12 of portion 6 of pack 3, and a rest position, in which it is detached from flaps 15. Transmission 70 also converts the above full one-way turn of pulley 68 into a back- and- forth movement of interacting surfaces 67 between a work position, in which interacting surfaces 67 press respective flaps 16 of each pack 3 onto respective walls 11 , and a rest position, in which they are detached from flaps 16 to permit travel of pack 3 along path B.

More specifically, transmission 70 comprises a cam 71 fitted to shaft 69 and engaged by a cam follower 72 integral with interacting surface 66; and two cams 73 fitted to shaft 69 and each engaged by a respective cam follower 100 integral with a respective interacting surface 67.

More specifically, cam 71 is fitted to shaft 69 in a position interposed axially between cams 73; and interacting surface 66 moves between its rest and work positions in a direction parallel to an axis G perpendicular to axes C and F and intersecting path B at station B₅.

Cam 71 defines a groove 101 extending eccentrically about axis F and housing cam follower 72.

Groove 101 is so shaped that, for each full one-way turn of cam 71 about axis F, cam follower 72 moves interacting surface 66 first from the work position to the rest position, and then from the rest position to the work position.

Similarly, cams 73 define respective grooves (only shown partly in Figure 8) extending eccentrically about axis F and housing respective cam followers 100.

Cam followers 100 are connected to respective interacting surfaces 67 by respective lever mechanisms 74. Each lever mechanism 74 comprises a lever 75 having a first end integral with respective cam follower 100, and a second end hinged to a plate 79 fixed to a frame of folding device 65; a plate 76 integral with respective interacting surface 67; and a lever 77 hinged at opposite ends to the second end of lever 75 and to plate 76 about respective axes perpendicular to axes F and G.

Each lever mechanism 74 also comprises a lever 78 hinged at opposite ends to plates 79 and 76 about respective axes perpendicular to axes F and G.

Levers 75, 77, 78 are rotated by cams 73 about plates 76, 79 to move interacting surfaces 67 between the work position and the rest position.

More specifically, lever mechanisms 74 and the grooves housing cam followers 100 are so designed that, for each full one-way turn of cams 73 about axis F, interacting surfaces 67 are first moved from the work position to the rest position, and then from the rest position to the work position. Heating device 60 (only shown partly in Figure 1) is fixed to frame 20 to interact with each pack 3 at station B₄ of path B.

Heating device 60 is fixed to wall 21 on the opposite side of hub 41 to axis C.

Heating device 60 comprises an air heating unit not shown; two first nozzles 61 (only one shown in Figure 1) connected to the air heating unit and for directing hot air onto the unfolded flaps 16 preparatory to heat sealing the flaps onto respective walls 11; and two second nozzles (not shown) connected to the air heating unit and for directing hot air onto the unfolded flaps 15 of each pack 3 preparatory to heat sealing the flaps onto respective walls 12. Conveyor 80 (Figures 1 and 3) comprises an endless belt 81 looped about a drive pulley 82 and a return pulley 83; and a number of push members 84 fitted given distances apart to belt 81, and which interact with portions 6 of respective packs 3 to move the packs from a loading unit to conveyor 40.

More specifically, push members 84 are equally spaced along belt 81, and travel, in use, along an endless path of the same shape as belt 81.

Push members 84 receive respective packs 3 from the loading unit (not shown) located upstream from conveyor 40 and adjacent to pulley 83. Packs 3 are then fed by respective push members 84 along a straight path sloping with respect to axis C, and are fed to conveyor 40 at a point adjacent to pulley 82 and at station B₁.

Belt 81 then moves each push member 84 from pulley 82 to pulley 83, where each push member 84 interacts with another respective pack 3. On conveyor 80, each pack 3 is positioned with portion 7 facing conveyor

40, and with portion 6 facing away from conveyor 40 and resting against relative push member 84.

Pulleys 82, 83 rotate about respective axes parallel to axis C. More specifically, the axis of pulley 82 is higher than that of pulley 83. As a result, packs 3 travel along an upward-sloping path from the input station to conveyor 40.

As shown in Figure 3, pulley 82 is fitted to a shaft 85 extending through wall 21 of frame 20. More specifically, at the opposite end to pulley 82, shaft 85 is connected functionally to a motor 88, of which only an output pulley 87 is shown in Figure 2.

Conveyor 80 also comprises a guard structure 86 extending alongside and over the portion of belt 81 along which packs 3 travel, to prevent packs 3 from falling laterally off or becoming detached from belt 81.

Conveyor 90 (only shown schematically in Figure 1) comprises a belt 91 looped about a drive pulley (not shown in Figure 1) powered by a motor 92, and about a return pulley (not shown).

Belt 91 comprises a number of push members 93 (only one shown in Figure 1), which engage respective packages 2 at station B₂ of path B, and feed packages 2, in a direction parallel to an active branch of belt 91, to an unloading unit (not shown) downstream from unit 1.

The active branch of belt 91 extends parallel to axis C.

As shown in Figure 2, wall 21 divides frame 20 into a first compartment housing motors 43, 88 and pulleys 52, 68, 87; and a second compartment housing the other parts of conveyors 40, 80 and folding devices 50, 65, and housing rails 22, 23, 24, 25, 26, 27, 28, and heating device 60.

As shown in Figure 1 , motor 92 is also housed in the first compartment.

Pulleys 87, 52, 68 are advantageously connected functionally to one another by an endless belt 95 shown in Figure 2.

One-way rotation of motor 88 therefore powers the forward movement of push members 84 and the back-and- forth movement of interacting surfaces 51, 66, 67.

More specifically, belt 95 comprises a first branch 96 extending between pulleys 87, 52 and kept taut by a belt tensioner; a second branch 97 extending between pulleys 52, 68; and a third branch 98 extending between pulleys 68, 87.

As shown in Figure 2, third branch 98 comprises a first end portion adjacent to pulley 87; and a second end portion adjacent to pulley 68 and sloping with respect to the first portion. To connect the first and second portion, branch 98 extends about a number of - in the example shown, three - guide pulleys.

Motor 88 is synchronized electronically with motor 43 of conveyor 40 and with motor 92 of conveyor 90.

More specifically, motors 43 and 88 are so synchronized that each clamping device 42 at station Bi receives a respective pack 3 from a respective push member 84.

Motors 43 and 92 are so synchronized that each push member 93 of conveyor 90 at station B₂ receives a respective package 2 from a respective clamping device 42. Operation of unit 1 will be described with reference to one pack 3, and as of the instant in which a push member 84 of conveyor 80 receives pack 3 from the loading unit at pulley 83.

Motor 88 rotates continuously in one direction to rotate belt 81 and feed push members 84 and relative packs 3 towards pulley 82.

At the same time, pulley 87 and, by means of belt 95, pulleys 52, 68 rotate continuously in one direction. In particular, pulleys 52, 68 rotate about axes D, F.

As push member 84 starts to rotate about the axis of pulley 82, the speed of belt 81 is such as to accelerate pack 3 towards conveyor 40 and in a direction substantially parallel to the travelling direction of pack 3 on belt 81.

Motors 88, 43 are so synchronized that pack 3, accelerated as described above, is gripped by the clamping device 42 located at station Bi.

More specifically, members 44 of clamping device 42 at station Bi are parted slightly to permit insertion of pack 3.

As soon as pack 3 is inserted inside relative clamping device 42, members 44 are brought together so that surfaces 45 rest on walls 10.

More specifically, pack 3 is housed inside clamping device 42 with portion 7 facing axis C, and with portion 6 projecting radially from surfaces 45. Pack 3 is moved along forming path B by conveyor 40 rotating clockwise about axis C.

Along the first portion of path B, surfaces 30 of rails 22 cooperate with the lateral ends of tab 13, and walls 32 of rails 25 with the lateral ends of tab 14.

Because of the reduction, along the first portion of path B, in the distance between surfaces 30 and corresponding walls 32, portions 6, 7 of pack 3 are pressed towards each other into a position perpendicular to axis A.

More specifically, walls 12 and flaps 15, 16 of portions 6, 7 are made perpendicular to axis A, and tabs 13, 14 are folded onto respective walls 12 to convert pack 3 to the Figure 10 configuration. By the time pack 3 reaches station B₃, the synchronization of motors 88, 43 has moved interacting surface 51 of folding device 50 into the work position, in which it compresses the intermediate portion of wall 12, between flaps 15, of portion 6 towards axis C. The above compression produces a slight translation of pack 3 towards axis

C, so that flaps 15 rotate about respective fold lines 17 into a position parallel to axis A, and flaps 16 rotate about respective fold lines 18 into a position sloping roughly ten degrees with respect to the plane of walls 12 of portion 7, as shown in Figure 11.

At this point, further travel of belt 95 produces further rotation of pulley 52, which, by means of transmission 53, moves interacting surface 51 into the rest position.

Conveyor 40 then moves pack 3 along the second portion of path B. Along the second portion of path B, rails 23, 25 fold flaps 15, 16 towards axis A so that, by the time they reach station B₄, they are positioned as shown in Figure 12.

This is achieved by virtue of the reduction in the radial distance between each rail 23 and corresponding rail 25, and by virtue of both rails 23 and rails 25 coming closer together along the second portion of path B.

More specifically, at station B₄, flaps 15, 16 slope roughly forty- five degrees with respect to axis A, and extend from respective fold lines 17, 18 away from axis C, as shown in Figure 12.

Walls 1 1 of pack 3 cooperate with respective rails 24 along the whole of the first and second portion of path B.

At station B₄, conveyor 40 stops, and heating device 60 blows hot air onto flaps 15, 16 of pack 3, preparatory to heat sealing the flaps to walls 12, 11.

Further operation of motor 43 of conveyor 40 feeds pack 3 along the third portion of path B. Along the third portion, rails 26, 27 fold respective flaps 15, 16 of pack 3 further to convert the pack from the Figure 12 to the Figure 13 configuration.

More specifically, rails 26, 27 fold flaps 15 towards walls 12 of portion 6, so that each flap 15 forms an angle of roughly ten degrees with walls 12, and fold flaps 16 towards walls 11, so that each flap 16 forms an angle of roughly ten degrees with relative wall 11.

This is achieved by virtue of the reduction in the distance between each rail 26 and corresponding rail 27 from ends 47, 48 to ends 49, 58. Folding as described above is also achieved by virtue of rails 26 coming closer together, in a direction parallel to axis C, along respective portions adjacent to ends 47, and by virtue of rails 27 coming closer together, in a direction parallel to axis C, along respective portions adjacent to ends 48.

At station B₅, conveyor 40 stops, and interacting surfaces 66, 67 of folding device 65 are moved into their respective work positions by belt 95 rotating pulley

68 in a first direction. In the work position, interacting surface 66 presses the heated flaps 15 onto walls 12 of pack 3, and interacting surfaces 67 press the heated flaps

16 onto walls 11 of pack 3 to complete package 2 (Figure 14).

The pressure applied as described above seals flaps 15, 16 to walls 12, 11. Next, further travel of belt 95 rotates pulley 68 further, still in said first direction, to detach interacting surfaces 66, 67 from flaps 15, 16.

Motor 43 is then operated again, and conveyor 40 feeds package 2 along the fourth portion of path B to station B₂.

Along the fourth portion, rails 28 cooperate with flaps 15 to keep them pressed onto walls 12 of portion 6 and so prevent detachment of flaps 15.

As clamping device 42 reaches station B₂, members 44 are parted slightly to withdraw surfaces 45 slightly from relative walls 10.

At this point, package 2 falls by gravity onto belt 91 of conveyor 90. By synchronizing motors 43, 92, a push member 93 on conveyor 90 receives the package 2 dropping from clamping device 42, and supplies it to the unloading unit.

The advantages of unit 1 according to the present invention will be clear from the foregoing description. In particular, unit 1 supplies packs 3 to conveyor 40 and moves interacting surfaces 51, 66, 67 back and forth between their respective work and rest positions by simply operating motor 88 a constant speed, and connecting motor 88 to pulleys 52, 68. Rotating motor 88, pulleys 87, 52, 68, and belt 95 at constant steady speed greatly reduces wear and fatigue of the various component parts of folding unit 1, thus prolonging the working life and increasing the output rate of unit 1.

Moreover, pulleys 52, 68 are connected to interacting surfaces 51, 66, 67 with no reducers or torque multiplying devices, thus reducing the number of component parts and simplifying maintenance and production of unit 1.

Unit 1 is also highly versatile, by catering to packs 3 of different sizes by simply adjusting the distance between rails 22, 23, 25 and between rails 26, 27.

Clearly, changes may be made to unit 1 as described and illustrated herein without, however, departing from the scope defined in the accompanying Claims. In particular, unit 1 may be used for producing other than parallelepiped- shaped packages.

More specifically, unit 1 may be used for producing wedge-shaped, so- called "Terra Wedge" (registered trademark), packages, which, very briefly, comprise a flat rectangular base wall; two isosceles-trapezium-shaped lateral walls projecting from respective opposite sides of the base wall; and by two triangular lateral walls projecting from the other sides of the base wall and forming, with the trapezoidal lateral walls, a wedge-shaped end portion opposite the base wall and including a transverse sealing strip of the package.

In which case, this would call for using fixed rails designed differently from rails 22, 23, 24, 25, 26, 27, 28, and folding devices having interacting surfaces operated and designed differently from interacting surfaces 51, 66, 67.

Claims

1) A folding unit (1) for packaging machines for packaging pourable food products, comprising: - conveying means (40) for feeding along a forming path (B) at least one sealed pack (3) containing a pourable food product and having a portion (6, 7) to be folded to form a finished package (2); and

- first folding means (50; 65) comprising at least one first interacting member (51; 66, 67) movable back and forth between a work position, in which it cooperates with said pack (3) along said path (B) to perform a first forming operation on the pack, and a rest position, in which it is detached from said pack (3); said first interacting member (51; 66, 67) being movable along a first trajectory intersecting said path (B) at a first station (B₃; B₅) of the path (B), where said first forming operation is performed; said first folding means (50; 65) comprising at least one first control member (52; 68) rotating about a first axis (D, F); and a first transmission (53; 70) functionally connecting said first control member (52; 68) and said first interacting member (51; 66, 67); characterized in that said first transmission (53; 70), in use, converts one- way rotation of said first control member (52; 68) into a back-and- forth movement of said first interacting member (51; 66, 67) between said work position and said rest position.

2) A unit as claimed in Claim 1, characterized in that said first transmission (53; 70) comprises at least one first cam (55; 71, 73) angularly integral with said first control member (52; 68) and engaged by a first cam follower (56; 72, 100) integral with said first interacting member (51; 66, 67); said first cam (55; 71, 73) and said first cam follower (56; 72, 100) being designed so that a full one-way turn of said first cam (55; 71, 73) about said first axis (D, F) produces a forward movement of said first interacting member (51; 66, 67) from said work position to said rest position, and a return movement of said first interacting member (51; 66, 67) from said rest position to said work position.

3) A unit as claimed in Claim 1 or 2, characterized by comprising second folding means (65; 50) in turn comprising at least one second interacting member

(66, 67; 51) movable back and forth between a work position, in which it cooperates with said pack (3) along said path (B) to perform a second forming operation on the pack, and a rest position, in which it is detached from said pack

(3); said second interacting member (66, 67; 51) being movable along a second trajectory intersecting said path (B) at a second station (B₅; B₃) of the path (B), where said second forming operation is performed; said second folding means (65, 50) comprising at least one second control member (68; 52) rotating about a second axis (F; D) and connected functionally to said first control member (52; 68); and a second transmission (70; 53) which, in use, converts one-way rotation of said second control member (68; 52) into a back- and- forth movement of said second interacting member (66, 67; 51) between said work position and said rest position.

4) A unit as claimed in Claim 3, characterized in that said second transmission (70; 53) comprises at least one second cam (71, 73; 55) angularly integral with said second control member (68; 52) and engaged by a second cam follower (72, 100; 56) integral with said second interacting member (66, 67; 51); said second cam (71, 73; 55) and said second cam follower (72; 100) being designed so that a full one-way turn of said second cam (71, 73; 55) produces a forward movement of said second interacting member (66, 67; 51) from said work position to said rest position, and a return movement of said second interacting member (66, 67; 51) from said rest position to said work position.

5) A unit as claimed in any one of the foregoing Claims, characterized by comprising a loading device (80) for supplying said conveying means (40) with said pack (3); said loading device (80) comprising:

- at least one push member (84) which is movable along an endless path extending, in use, in one direction, and pushes said pack (3), along at least one portion of said endless path, onto said conveying means (40); and

- a third control member (82) rotating about a third axis and connected functionally to said push member (84) by a transmission member (81); said transmission member (81), in use, converting a full one-way turn of said third control member (82) into a forward movement of said push member (84) along said endless path.

6) A unit as claimed in Claim 5, characterized in that said third control member (82) is connected functionally to at least one of said first and said second control member (52; 68).

7) A unit as claimed in Claim 6, characterized in that said third control member (82) is connected functionally to both said first and said second control member (52; 68), and at least one of said first, second, and third control member (52; 68; 82) is connected functionally to a first drive member (88).

8) A unit as claimed in Claim 7, characterized in that said first, second, and third control member (52; 68; 82) are connected functionally to each other by a drive belt (95).

9) A unit as claimed in Claim 7 or 8, characterized in that said conveying means (40) comprise:

- a second drive member (43); and

- at least one clamping device (42) which receives said pack (3) from said loading device (80) at an initial station (Bi) of said path (B), and is connected functionally to said second drive member (43) so as to be rotated, in use, about a further axis (C); said first and said second drive member (88, 43) being synchronized so that said conveying means (40) position said clamping device (42) at said initial station (Bi) as said push member (84) supplies said pack (3) to the conveying means (40).

10) A unit as claimed in Claim 9, characterized by comprising an unloading device (90) for removing said package (2) from said conveying means (40) at a final station (B₂) of said path (B), and unloading said package (2) off said unit (1); said unloading device (90) comprising:

- at least one further push member (93) for pushing said package (2) along an unloading path at least partly facing said path (B); and

- a third drive member (92) connected functionally to said further push member (93); said second and third drive member (43, 92) being synchronized so that said further push member (93) and said clamping device (42) are positioned facing each other at said final station (B₂).