HK1077791B - A forming unit for producing sealed packages from a tube of sheet packaging material - Google Patents

Description

Forming apparatus for producing sealed packages from a tube made of sheet packaging material

Technical Field

The present invention relates to a forming apparatus for producing sealed packages from a tube of sheet packaging material filled with a pourable food product.

Background

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

A typical example of such a package is a parallelepiped-shaped package for liquid or pourable food products known as Tetra Brik Aseptic (registered trade mark), which is formed by folding or sealing a web of laminated packaging material.

The packaging material has a multilayer structure comprising a layer of paper material covered on both sides with layers of heat-seal plastic material, for example polyethylene; and, in the case of aseptic packages for long-storage products, such as UHT milk, the packaging material also comprises a layer of oxygen barrier material, defined for example by a sheet of aluminium, which is superimposed on a layer of heat-seal plastic material eventually defining the inner face of the package contacting the food product, and is in turn covered with another layer of heat-seal plastic material.

As is known, such packages are formed on fully automatic packaging machines, on which a continuous tube is formed from a web of packaging material fed. More specifically, the web of packaging material is unwound from a reel and passed through an aseptic chamber on the packaging machine, in which sterilization takes place, for example by applying a chemical sterilizing agent, such as hydrogen peroxide, which is later evaporated by heating and/or subjecting the packaging material to radiation of a suitable wavelength and intensity; the web thus sterilized is maintained in a closed, sterile environment and is folded and sealed longitudinally in a known manner into a cylindrical shape to form a continuous tube.

The tube of packaging material, which in other words forms an extension of the aseptic chamber, is fed continuously in a vertical direction, filled with the sterilized or sterile-processed food product, and passed through a forming apparatus for forming the individual packages.

The forming apparatus comprises two pairs of gripping members acting cyclically and continuously on the tube of packaging material to grip and heat-seal it along equally spaced cross sections, thus forming a continuous pillow-like packaging band connected to each other by respective transverse sealing bands, i.e. sealing bands extending perpendicularly to the travelling direction of the tube. The pillow packs are separated by cutting the relative transverse sealing bands and are then fed to a folding station where they are folded mechanically into the finished parallelepiped shape.

The tube portion held between each pair of the holding members is heat sealed by a heating device supported by one of the holding members and serving to locally melt the two layers of heat-seal plastic material held firmly between the holding members.

When the heat sealing is completed, one cutting member is actuated to cut the tube along the centre line of the transverse sealing band, thus separating the pillow packs from the bottom end of the tube of packaging material, which cutting member is supported by one of the jaws and interacts with the tube of packaging material, so that the bottom end is sealed transversely, and the jaws are opened when the bottom dead centre position is reached to avoid interference with the above-mentioned portion of the tube, while the other pair of jaws, operating in the same way, is moved downwards from the top dead centre position, repeating the clamping/forming, sealing and cutting operations as described above.

One problem encountered with known forming apparatuses concerns the so-called "decoration correction" systems.

I.e. on the part which finally forms the outer surface of the package, the web of packaging material usually comprises a series of equally spaced printed images or decorations, so that the web must be supplied to the forming apparatus in such a way that, in the case of a continuous decoration, the formation, sealing and cutting of the packages takes place "in register" with the succession of decorations. In actual use, since the decorations are printed equidistantly apart, the position of each decoration relative to the position of the jaws on the forming device may vary, firstly because of the different deformations of the packaging material caused by the mechanical pressure exerted by the jaws on the packaging material, and secondly because of the pulsating pressure of the pourable food product inside the tube of packaging material. There is therefore a need for a system for correcting the position of decorations, since on packaging machines operating at very high output speeds, even small variations in the position of the decorations with respect to the theoretical register position may increase over time, if not corrected in real time, resulting in the production of unacceptable packages which must be discarded.

On modern packaging machines, such systems comprise an optical sensor for detecting the position of the bar code on each package; and a control unit for comparing the detected position with a theoretical position.

On some commercial machines, each pair of jaws has a pair of traction members for pulling the tube of packaging material, which are fitted movably to one of the jaws in each pair of jaws, forming triangular projections at the top and bottom corners of the pillow pack; and, upon detection of a decoration position error, the control unit adjusts the speed of the feed motor of the web of packaging material. If the correction is not sufficient, the pulling member is controlled to slightly increase or decrease the pulling force on the wrapper. On other machines, the control unit acts directly on the traction member, without it being possible to adjust the speed of the packaging material web feed motor; and the operation is repeated until the position of the decoration coincides with the theoretical position.

Recently, solutions have been conceived whereby the position of the decoration on the packaging material is controlled by adjusting the movement and timing of the pair of clamps acting on the tube.

For example, as described in italian patent 1296062, the traction means are operated by a continuous linear actuator, for example a pneumatic cylinder, which is mounted on the supporting structure of the forming apparatus, is actuated by the control unit of the decoration correction system and is connected to the traction means by transmission means.

More specifically, in the case described, the transmission means comprise an actuating rod fitted movably to the gripping member provided with the traction member, fitted at one end with a tappet member and connected at the opposite end to the traction member by means of a respective articulated lever. The tappet member is in turn mounted for movement along a cam profile, which is adjustably mounted on the support structure of the forming apparatus, connected by a motion transfer assembly to the drive member and movable relative to the support structure by the drive member.

In other words, the operation of the drawing members requires extremely complex, cumbersome transmission means to transmit the movement from the driving member mounted on the fixed part of the forming apparatus to the drawing member mounted on the movable gripping member, thus involving a large number of parts on the support structure and gripping member of the forming apparatus, thus considerably increasing the overall cost of the packaging machine and increasing the time spent on mounting and dismounting the forming apparatus for any maintenance work.

The complexity of the known forming apparatuses is further increased by the grippers, which, in addition to the traction members, usually comprise movable members, for example so-called "volume boxes", which cooperate to determine the volume and shape of the pillow packs formed and which require dedicated actuating means.

Disclosure of Invention

It is an object of the present invention to provide a forming apparatus for producing sealed packages from a tube of sheet packaging material filled with a pourable food product, and designed to eliminate the drawbacks normally associated with the aforementioned known apparatuses.

According to the present invention, there is provided a forming apparatus for producing sealed packages from a tube of sheet packaging material fed along a feed path and filled with a pourable food product, said apparatus comprising gripping means comprising at least two forming assemblies, each having a pair of gripping members cyclically co-operating with one another and cyclically acting on said tube to grip and seal said tube at equally spaced cross sections defining opposite sealing bands of said packages; -interaction means movably fitted to said gripping means, and-actuating means for operating said interaction means, said interaction means comprising traction means for exerting a pulling force on the tube of packaging material to correct the travel of said tube along said feed path; characterized in that said actuating means are completely mounted on said gripping means and comprise, for each of said gripping members, a first control actuator and transmission means interposed between said first actuator and said traction means.

In other aspects, the drawing device comprises two movable members supported by one of the pair of grippers of each of the forming assemblies and interacting with the tube on opposite sides. Said movable member comprising a respective pin which rotates with respect to the associated gripping member; and a corresponding projection eccentrically supported by the pin. Each of the first actuators includes a first output movable in a direction that intersects the feed path and the axis of the pin; and for each of said jaws, said transmission means comprise a lever having a connecting portion hinged to said first output and defining two fixed portions, and an arm hinged to said fixed portions and eccentrically supported by said pin for actuating said movable member. Said interaction means comprise a box means having a predetermined shape and volume of the portion surrounding said tube and eventually defining said package. For each of said forming assemblies, said box device comprises a pair of boxes movably connected to said clamp and cooperating with each other to define a cavity of predetermined shape and volume and to enclose said tube. For each of said forming assemblies, said actuating means comprises pushing means selectively driven to clamp said pair of magazines together. For each said gripper, said pushing means comprises a second control actuator having a second output movable in a direction that intersects said feed path of said tube; and a toggle-like mechanism extending crosswise to the moving direction of the second output, the toggle-like mechanism being interposed between one of the grippers and one of the pair of magazines, and being actuated by the second output.

Drawings

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

figures 1 and 2 show respective front and side views of a forming apparatus according to the present invention with parts removed for clarity purposes, which produces sealed packages from a tube of sheet packaging material filled with a pourable food product;

FIG. 3 shows an exploded rear perspective side view of one of the seal holders of the forming apparatus of FIGS. 1 and 2 with parts removed for clarity;

FIG. 4 shows a front side perspective view of the clamp of FIG. 3;

FIG. 5 shows a rear elevational view, on a larger scale, of a portion of the clamp of FIG. 3; and

fig. 6 shows a rear side perspective view of a variant of the sealing device of fig. 3, with parts removed for clarity.

Detailed Description

Number 1 in figure 1 indicates as a whole a forming apparatus for producing sealed packages 2 from a tube 3 of sheet packaging material, tube 3 having an axis a, which is filled with pourable food product and is fed along a vertical path P parallel to axis a.

More specifically, tube 3 is formed in a known manner by longitudinally folding and sealing a strip of packaging material and is filled with the food product to be packaged upstream from apparatus 1.

The strip of packaging material has a multilayer structure (not shown) and conveniently comprises a layer of paper material covered on both sides with layers of heat-seal plastic material, for example polyethylene. In the case of aseptic packages for long-storage products, such as UHT milk, the packaging material also comprises a layer of oxygen-barrier material, defined for example by a sheet of aluminium, which is superimposed on a layer of heat-seal plastic material eventually defining the inner face of package 2 contacting the food product, and is in turn covered with another layer of heat-seal plastic material.

On the side which ultimately determines the outer surface of the packages 2, the web of packaging material has a succession of graphics or decorations which are repeated at equal intervals.

The apparatus 1 comprises a supporting structure 4 defining two vertical guides 5, the two guides 5 being arranged symmetrically with respect to a central longitudinal vertical plane M of the apparatus 1, the plane M passing through the axis a and the respective axes of the two guides 5 lying in a central transverse vertical plane T of the apparatus 1, the axis a thus defining the intersection of the planes M and T.

The apparatus 1 comprises, in a known manner, two forming assemblies 6, 6' which move vertically along respective guides 5 and interact alternately with the tube 3 of packaging material to grip and heat seal the cross section of the tube.

Since the assemblies 6, 6 'are symmetrical with respect to the plane M, only one (assembly 6) is shown in detail in fig. 2 and described below, the corresponding parts of the assemblies 6, 6' being indicated in the figures with the same reference numerals.

With reference to fig. 1 and 2, the assembly 6 essentially comprises a slider 7 moving along the respective guide 5; and two gripping members 8a, 8B hinged at the bottom to the slider 7 about respective horizontal axes B parallel to and symmetrical with respect to the plane T, so as to open and close substantially like a book.

The reciprocating movement of the slider 7 and the opening/closing movement of the jaws 8a, 8b are controlled in a known manner (not depicted) by pairs of vertical rods (not shown) which are in turn controlled by rotary cams or servomotors.

More specifically, each clamp 8a, 8B comprises a main control body 10, substantially in the form of a quadrangular plate (fig. 1 and 2) suitably ribbed, which extends along a work plane V of the clamp 8a, 8B containing the respective axis B, the main control body 10 being hinged to the slide 7 near its bottom and having, on the side opposite to the plane V, a control arm 11 projecting from one surface of the body 10, the main control body 10 being actuated in a known manner (not shown) by one of said vertical rods.

The jaws 8a, 8B also comprise respective supporting arms 12a, 12B, which supporting arms 12a, 12B are fixed to the top end of the respective main body 10 and project towards and beyond the plane M in a direction parallel to the respective axis B and substantially along the respective work plane V, so as to be located on opposite sides of the tube 3.

The projecting portions of the supporting arms 12a, 12b are provided with respective rod-like sealings 13a, 13b (figure 2), the sealings 13a, 13b interacting with the tube 3 and being able to be determined, for example, by an inductor for generating an electric current in the aluminium layer of the packaging material and thus melting the thermoplastic layer due to the joule effect, and by a contrast pad (or matching pad) providing the necessary mechanical support to bring the clamping of the tube 3 to the required pressure.

The gripping members 8a, 8b are movable between a closed position in which the respective sealing members 13a, 13b grip the pipe 3 and a fully open position.

In the transverse sealing step, the tube 3 is heat-sealed along equally spaced cross sections to form respective sealing bands 15.

Above the respective seal 13a, 13b, the supporting arms 12a, 12b of the jaws 8a, 8b support respective so-called "volume boxes" for controlling the volume of the packages 2, which are shown in more detail in fig. 6.

The boxes 16 are hinged at the bottom, about respective axes C parallel to axis B, to the arms 12a, 12B of the respective jaws 8a, 8B, and are held in a predetermined position on the arms 12a, 12B by known elastic means, not shown.

The boxes 16 have a C-shaped cross section open at the front and are then sealed transversely by seals 13a, 13b, the boxes 16 cooperating with each other to define a cavity of given shape and volume which encloses the tube 3 in a configuration of rectangular section.

Each magazine 16 comprises a flat rear wall 17, rear wall 17 facing arms 12a, 12b of respective jaws 8a, 8b and being substantially parallel to relative plane V; and two flat side walls 18, the side walls 18 extending perpendicularly from two opposite side edges of the rear wall 17.

This forming step produces pillow packs 2 having a main portion 20, the main portion 20 being of the same shape and volume as the final pack; and creating a transition portion 21 connecting the main portion 20 to the respective adjacent sealing band 15, the transition portion 21 being laterally determined by a substantially triangular surface 22.

As shown in figures 2, 3, 4 and 5, one 8a of the gripping members 8a, 8b comprises, in a known manner, two movable drawing members 23, the movable drawing members 23 serving to control the longitudinal feeding of the tube 3 through the apparatus 1.

The movable member 23 is located symmetrically on each side of the tube 3 with respect to the axis a and adjacent to the tube 3, and more specifically the movable member 23 comprises a respective pin 24 mounted in an axially fixed rotary manner through a respective hole formed through the supporting arm 12a and having an axis D, E perpendicular to the plane V; and comprises a corresponding projection 26 eccentrically supported by pin 24, projection 26 interacting with the packaging material of tube 3.

More specifically, the projections 26 project from respective front ends of the pins 24, which face the tubes 3, so that the projections 26 project from the supporting arms 12a on the same side of the relative seal 13a and above the relative seal 13a, and are curved at their concave portions, the projections 26 facing in the direction of the tubes 3 and tapering in section.

By means of an actuating device 27, movable member 23 is counter-rotated about respective axis D, E, i.e. so as to draw equal counter-angles, thus moving projections 26 symmetrically about path P. Actuating device 27 acts during the forming step so as to cause projections 26 to act on sides 22 of transition portion 21 of pillow packs 2 and to apply a varying pulling force on tube 3 in the direction of feed of the tube, so as to correct any error in the position of the decoration on the packaging material.

More specifically, actuating device 27 is controlled by a known control unit, not shown since it does not form part of the present invention, which detects the actual position of the decoration on the packaging material forming package 2 by means of one or more optical sensors and compares the actual position with a theoretical reference position, so as to adjust the pulling force exerted by movable traction members 23. Alternatively, actuating device 27 may operate movable member 23 between two predetermined positions to simply form individual packages 2.

According to an important feature of the invention, the actuating means 27 are fitted to and completely supported by the supporting arm 12a of the clamp 8 a.

More specifically, the actuating means 27 comprise a continuous linear actuator 28, for example a pneumatic cylinder; and comprises a transmission 29 interposed between the actuator 28 and the pin 24 of the movable element 23.

The actuator 28 comprises a casing 30 fixed to the supporting arm 12a of the clamp 8a, adjacent to the main body 10, and having an axis F parallel to the direction of maximum extension of the supporting arm 12 a; and a movable member 31 fitted to slide axially in the housing 30 and having a rod 32 projecting from the housing 30 and connected to the transmission mechanism 29.

As shown in particular in fig. 3 and 5, the transmission 29 comprises a contoured rod 33, the rod 33 having an end 34 hinged to the free end of the rod 32 and defining two fixed portions 35, 36, to which respective actuating arms 37, 38 for actuating the movable member 23 are hinged, and the fixed portions 35, 36 being fitted to and radially projecting from the rear ends of the respective pins 24.

More specifically, the rod 33 is substantially S-shaped, extends along a plane parallel to the plane V and faces the side of the supporting arm 12a opposite to the side on which the respective seal 13a projects. In the example shown, one 35 of the fixed portions 35, 36 is defined by the end of the rod 33 opposite to the end 34, while the other fixed portion 36 is defined by an intermediate portion of the rod 33.

The actuating arms 37, 38 form different angles with the lever 33, so that the linear displacement of the lever 32 corresponds to the relative rotation of the movable member 23 about the respective axis D, E.

In the variant of figure 6, in addition to the actuating device 27, the gripping member 8a of each forming assembly 6, 6' supports a pushing device 40, which pushing device 40 acts on the relative magazine 16 to grip it against the corresponding magazine 16 of the gripping member 8 b. Obviously, a similar pushing device is fitted in exactly the same way on the gripper 8b of each forming assembly 6, 6' to actuate the relative magazine 16.

The pushing means 40 comprise a linear actuator 41, for example a pneumatic cylinder, fitted to the arm 12a of the clamp 8a and parallel to the cylinder 28; and comprises a toggle-like mechanism 42 interposed between the actuator 41 and the rear portion of the relative magazine 16.

More specifically, actuator 41 comprises a housing 43 fixed to supporting arm 12a of clamp 8a, adjacent to main body 10, and having an axis G parallel to axis F; and comprises a movable member 44 fitted to slide axially inside the casing 43 and having a rod 45 projecting from the casing 43 and connected by its free end to the toggle-like mechanism 42.

Toggle-like mechanism 42 comprises two levers 46, 48 which extend crosswise to lever 45 of movable member 44 and have adjacent ends hinged to each other and to lever 45, and opposite ends hinged respectively to rear wall 17 of relative box 16 and to supporting arm 12a, close to the side of supporting arm 12a facing lever 33.

The lever 45 is movable between a forward position, corresponding to maximum extension from the casing 43, in which the lever 45 holds the levers 46, 48 substantially perpendicular to the rear wall 17 of the relative magazine 16, so as to exert maximum pressure on the magazine 16 of the opposite clamp 8b, and a retracted position, corresponding to minimum extension from the casing 43.

In actual use, the gripping members 8a, 8b of each forming assembly 6, 6' are closed when the assembly is moved downwards, so as to grip the tube 3 with the lower vertical assembly in motion at a speed equal to the running speed of the tube 3. More specifically, the jaws 8a, 8b of each forming assembly 6, 6' are drawn together to gradually deform the tube 3 and flatten it at one cross-section or transverse band. At this point, the seals 13a, 13b seal two overlapping portions of the packaging material, which form a flattened transverse band.

Once the heat-sealing is completed, boxes 16 of jaws 8a and 8b are drawn forward together to define a cavity of parallelepiped shape defining the volume of main portion 20 of formed package 2.

Magazines 16 of opposite jaws 8a, 8b are pushed into contact with each other, opposite the respective elastic means and by actuation of respective pushing means 40. More specifically, the movement of the lever 45 of each actuator 41 opens the levers 46 and 48 of the toggle-like mechanism 42 to a position in which the levers 46 and 48 are substantially aligned with each other, thus pushing the relative magazine 16 against the opposite magazine 16.

During the above-described forming step, in cooperation with the grippers 8a, 8b, the actuator 28 is operated to actuate the movable member 23. More specifically, rod 32 protrudes from casing 30 (fig. 5) along axis F, so as to move rod 33; and movement of the rod 33, by actuating the arms 37, 38, causes the movable member 23 to rotate in the opposite direction to pull the tube 3 downwards.

In a position close to the bottom dead centre in the downward stroke of each forming assembly 6, 6', the grippers 8a, 8b open to release the tube 3, continue to open as they move upwards and are fully open before reaching the top dead centre position; at this point, the grippers 8a, 8b start to close and are fully closed as they start to move downwards.

Obviously, the movement of the two forming assemblies 6, 6' is offset by half a cycle: when the forming assembly 6' is moved downwards and the jaws 8a, 8b are closed, the forming assembly 6 is moved upwards and the jaws 8a, 8b are opened so as not to interfere with each other.

From the foregoing description, the advantages of the device 1 according to the teachings of the present invention will be apparent.

In particular, by integrally and directly fitting the actuating means 27 of the movable member 23 to the relative jaws 8a, 8b, or the pushing means 40 of the box 16 to the relative jaws 8a, 8b, the number of parts of the forming assemblies 6, 6' is considerably reduced, thus simplifying the assembly, reducing the costs and the overall weight of the apparatus 1, and therefore allowing the apparatus 1 to be assembled and disassembled relatively quickly for any maintenance work.

Clearly, changes may be made to apparatus 1 as described herein without, however, departing from the scope of the accompanying claims.

In particular, the apparatus 1 may comprise two sets of gripping members 8a and 8b forming part of respective chain conveyors which in turn define respective endless gripping feed paths, the gripping members 8a and 8b extending on opposite sides of the feed path of the tube 3 and cooperating cyclically with one another in pairs. In this case, each forming assembly 6, 6' is defined by one gripper on one of the two conveyors and an opposite gripper on the other conveyor.

Claims (8)

1. A forming apparatus (1) for producing sealed packages (2) from a tube (3) of sheet packaging material fed along a feed path (a) and filled with pourable food products, said apparatus (1) comprising gripping means (6, 6 ', 8a, 8b) comprising at least two forming assemblies (6, 6') each having a pair of jaws (8a, 8b) cyclically cooperating with each other and cyclically acting on said tube (3) to grip and seal it at equally spaced cross sections defining opposite sealing bands (15) of said packages (2); -interaction means (16, 17, 23, 24, 26) movably fitted to said gripping means (6, 6', 8a, 8b), and actuation means (27, 28, 29, 31, 33-38, 40, 41, 42, 44) for operating said interaction means (16, 17, 23, 24, 26), said interaction means (16, 17, 23, 24, 26) comprising traction means (23, 24, 26) for exerting a pulling force on the tube (3) of packaging material to correct the running of said tube along said feed path (a); characterized in that said actuating means (27, 28, 29, 31, 33-38, 40, 41, 42, 44) are completely mounted on said gripping means (6, 6', 8a, 8b) and comprise, for each of said grippers (8a, 8b), a first control actuator (28, 31) and transmission means (29, 33-38) interposed between said first actuator (28, 31) and said traction means (23, 24, 26).

2. Apparatus as in claim 1, characterized in that said drawing means (23, 24, 26) comprise two movable members (23) supported by one (8a) of said pairs of jaws (8a, 8b) of each of said forming assemblies (6, 6') and interacting with said tube (3) on opposite sides.

3. The apparatus according to claim 2, wherein the movable member (23) comprises a respective pin (24), the pin (24) rotating with respect to the relative grip (8 a); and a corresponding projection (26), said projection (26) being eccentrically supported by said pin (24).

4. Apparatus according to claim 3, wherein each of said first actuators (28) comprises a first output (31) movable in a direction (F) crosswise to the axes (D, E) of said feed path (A) and of said pins (24); and in that for each of said jaws (8a, 8b), said transmission means (29, 33-38) comprise a rod (33) having a connecting portion (34) hinged to said first output (31) and defining two fixed portions (35, 36), and an arm (37, 38) hinged to said fixed portions (35, 36) and eccentrically supported by said pin (24) for actuating said movable member (23).

5. The apparatus according to claim 1, characterized in that said interaction means comprise box means (16, 17) having a predetermined shape and volume of a portion (20) surrounding said tube (3) and eventually defining said package (2).

6. The apparatus according to claim 5, characterized in that said box means (16, 17) comprise, for each of said forming assemblies (6, 6'), a pair of boxes (16) movably connected to said jaws (8a, 8b) and cooperating with each other to define a cavity of predetermined shape and volume and to enclose said tube (3).

7. The apparatus according to claim 6, wherein, for each of said forming assemblies (6, 6'), said actuating means (27, 28, 29, 31, 33-38, 40, 41, 42, 44) comprise pushing means (40, 41, 42, 44) selectively driven to clamp said pair of magazines (16) together.

8. Apparatus according to claim 7, wherein, for each of said grippers (8a, 8b), said pushing means (40, 41, 42, 44) comprise a second control actuator (41) having a second output (44) movable in a direction (G) crosswise to said feed path (A) of said tube (3); and a toggle-like mechanism (42) extending crosswise to the direction of movement (G) of the second output (44), the toggle-like mechanism (42) being interposed between one of the grippers (8a, 8b) and one of the pair of magazines (16) and being actuated by the second output (44).