EP3321192A1

EP3321192A1 - Forming member for controlling the volume of packs of pourable food products formed from a tube of packaging material

Info

Publication number: EP3321192A1
Application number: EP16198381.2A
Authority: EP
Inventors: Massimiliano BARBI; Roberto De Pietri Tonelli; Stefano Paradisi; Manuel ROCCHI; Davide ZANICHELLI
Original assignee: Tetra Laval Holdings and Finance SA
Current assignee: Tetra Laval Holdings and Finance SA
Priority date: 2016-11-11
Filing date: 2016-11-11
Publication date: 2018-05-16

Abstract

A forming member for controlling the volume of packs (3) of pourable food products formed from a tube (2) of packaging material comprises a forming half-shell (21) and a supporting element (30) supporting said forming half-shell (21), wherein said forming half-shell (21) comprises forming walls (25, 26) adapted to interact with said tube (2) and wherein said supporting element (30) comprises a connecting portion (33) intended to be connected to a jaw (8a, 8b) of a packaging machine and a forming portion (37) intended to interact with said tube (2) to form said packs (3), said forming portion (37) comprising a plurality of grooves (38).

Description

The present invention relates to a forming member for controlling the volume of packs of pourable food products formed from a tube of packaging material.
As is known, many liquid or 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 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 base layer, e.g. of paper or mineral-filled polypropylene, and a number of layers of heat-seal plastic material, e.g. polyethylene film, covering both sides of the base layer.
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, e.g. an aluminium foil or ethylene vinyl alcohol (EVOH), which is superimposed on a layer of heat-seal plastic material, and is in turn covered with another layer of heat-seal plastic material forming the inner face of the package eventually contacting the food product.
As is known, packages of this sort are normally produced on fully automatic packaging machines, on which a continuous tube is formed from the web-fed packaging material. The web of packaging material is sterilized in the packaging machine, e.g. by applying a chemical sterilizing agent, such as a hydrogen peroxide solution, which, once sterilization is completed, is removed from the surfaces of the packaging material, e.g. evaporated by heating, from the surfaces of the packaging material.
The sterilized web of packaging material is maintained in a closed, sterile environment, and is folded into a cylinder and sealed longitudinally to form a tube.
The tube is fed in a vertical direction parallel to its axis, and is filled continuously with the sterilized or sterile-processed food product.
The packaging machine comprises a forming unit that interacts with the tube to heat seal it at equally spaced cross sections and so form pillow packs connected to the tube by transverse sealing bands.
The pillows packs are then conveyed to a downstream folding unit, where they are folded so as to generate corresponding packages.
More specifically, the forming unit comprises two forming assemblies movable along respective guides, and which interact cyclically and successively with the tube to heat seal the packaging material of the tube.
Each forming assembly comprises a slide which moves upwards and downwards along the respective guide, and two jaws hinged to the slide and movable between a closed configuration, in which they cooperate with the tube to heat seal the tube, and an open configuration, in which they are detached from the tube.
More specifically, the jaws of each forming assembly are moved between the open configuration and closed configuration by respective actuating devices.
The movements of the forming assemblies are offset by a half-period. That is, one forming assembly moves upwards, with its jaws in the open configuration, while the other forming assembly moves downwards, with its jaws in the closed configuration, to prevent the assemblies from clashing.
The jaws of each forming assembly are fitted with respective sealing members, which cooperate with opposite sides of the tube, and comprise, for example, a heating member and a member made of elastomeric material, which provides the necessary mechanical support to grip the tube to the required pressure.
Each forming assembly also comprises two forming members that have respective forming half-shells and are supported by the respective jaws.
In particular, each of the forming half-shell is hinged to a respective supporting element that, in turn, is connected to the respective jaw.
The two forming half-shells move cyclically between an open position, in which they are detached from the tube, and a closed position, in which they contact the tube and fold the portion of the tube between two consecutive sealing sections to define and control the volume of the pack being formed.
More specifically, the sealing device of the first forming assembly seals a first end portion of the pack being formed, and the forming half-shells of the first forming assembly control the volume of the pack, and the sealing device of the second forming assembly seals a second end portion of the pack being formed, opposite to the first end portion.
In one version of the known filling machines, the pack is formed "upside down" and therefore the above mentioned first end portion corresponds to a top portion of the pack and the above-mentioned second end portion corresponds to a bottom end portion of the pack.
The forming half-shells may be spring-loaded by respective springs into the open position, and have respective rollers, which cooperate with respective cams designed to move the forming half-shells into the closed position by the time the forming assembly reaches a predetermined position as it moves down.
Each forming half-shell has a C-shaped cross section, and comprises a main wall and two sidewalls substantially parallel to each other and projecting towards the axis of the tube of packaging material from respective opposite end edges of the main wall.
In the closed position, the main walls are located on opposite sides of the tube axis, are parallel to each other, and cooperate with respective first portions of the tube.
In the closed position, the sidewalls of one forming half-shell cooperate with respective second portions of the tube to control the volume of the pack being formed, and, on the opposite side to the relative main wall, face corresponding sidewalls on the other forming half-shell.
The above-mentioned supporting element cooperates with the forming half-shell hinged thereto to form the pack. In particular, the supporting element forms a region of the pack close to the above mentioned first end portion, e.g. close to the top portion of the pack.
A drawback of the known forming members is that the packaging material may not be able to properly slide on the supporting element. In particular, different portions of the packaging material may slide in different ways with respect to the supporting element. This causes a mispositioning of the tube of packaging material with respect to the forming half-shell and the respective supporting element. In this way the pack may have forming defects, like dents, or similar, in the region thereof that - during forming - is arranged close to the supporting element.
An object of the invention is to improve the forming members for controlling the volume of packs of pourable food products formed from a tube of packaging material.
Another object of the invention is to provide a forming member for controlling the volume of packs of pourable food products formed from a tube of packaging material in which the packaging material is properly positioned during forming of a pack.
Another object of the invention is to provide a forming member for controlling the volume of packs of pourable food products formed from a tube of packaging material in which the packaging material can easily slide with respect to a supporting element supporting a forming half-shell, so that the packaging material is correctly positioned with respect to the supporting element and the forming half-shell during forming of a pack.
According to the invention, there is provided a forming member for controlling the volume of packs of pourable food products formed from a tube of packaging material, comprising a forming half-shell and a supporting element supporting said forming half-shell, wherein said forming half-shell comprises forming walls adapted to interact with said tube and wherein said supporting element comprises a connecting portion intended to be connected to a jaw of a packaging machine and a forming portion intended to interact with said tube to form said packs, characterized in that said forming portion comprises a plurality of grooves.
Owing to the invention, the contact area between the supporting element and the packaging material forming the tube is reduced compared to the known forming members. In this way, the adhesion of the packaging material (in particular of the outer layer of the packaging material that is made of heat-seal plastic material, for example polyethylene) to the supporting element is correspondingly reduced. The packaging material can, therefore, easily slide on the supporting element and be properly positioned with respect to the forming member. In this way, the defects in the packs may be significantly reduced.
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 is a perspective view of (a part) of a forming unit for forming sealed packs from a tube of a packaging material, which comprises a forming member according to the invention, the forming member being shown in a closed configuration;
Figure 2 is a side view of the forming unit of Figure 1, the forming member being shown in an open configuration;
Figure 3 is a perspective view of a sealed package obtained by a folding a sealed pack in a folding unit which is arranged downstream of the forming unit of Figure 1;
Figure 4 is a section along line VI-VI of Figure 1, with parts removed for clarity;
Figure 5 is a perspective view of an embodiment of a supporting element of the forming member according to the invention;
Figure 6 is a perspective view of another embodiment of a supporting element of the forming member according to the invention.
Figures 1, 2 and 4, show a forming unit 1 for producing sealed packs 3 of a pourable food product, such as pasteurized milk or fruit juice, from a tube 2 of sheet packaging material.

The packaging material has a multilayer structure (not shown), and comprises a layer of fibrous material, normally paper, covered on both sides with respective 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 also comprises a layer of gas- and light-barrier material, e.g. aluminium foil or ethylene vinyl alcohol (EVOH) film, which is superimposed on a layer of heat-seal plastic material, and is in turn covered with another layer of heat-seal plastic material forming the inner face of the package eventually contacting the food product.
The tube 2 is formed in known manner by longitudinally folding and sealing a web (not shown) of packaging material, is filled by a pipe (not shown) with the sterilized or sterile-processed food product for packaging, and is fed, in known manner not shown, along a vertical path parallel to an axis A of the tube.
The forming unit 1 interacts with the tube 2 to heat seal the tube 2t at equally spaced cross sections and forms a number of pillow packs 3 connected to the tube 2 by sealing bands crosswise to axis A.
The packs 3 are then conveyed and folded into corresponding packages 4 (Figure 3) in a folding unit (not shown) which is arranged downstream of the forming unit 1.
In the embodiment shown in Figure 3, the package 4 extends along an axis B and comprises:

a slanted top wall 100 inclined relative to axis B;
a bottom wall 101 orthogonal to axis B;
a convex front wall 102 and a flat rear wall 103, which extend between the top wall 100 and the bottom wall 101; and
a first lateral wall 104 and a second lateral wall 105, which extend between the top wall 100 and the bottom wall 101 and between the front wall 102 and the rear wall 103.

Furthermore, the convex front wall 102 is laterally bounded by two curved crease lines 107 which are opposite to each other and extend between the top wall 100 and the bottom wall 101.
In another embodiment, not shown, the package 4 has a substantially parallelepiped shape, i.e. it has a top wall that is substantially parallel to the bottom wall, and a front wall that is substantially parallel to the rear wall.
The forming unit 1 comprises two forming assemblies 6 that move vertically along respective vertical cylindrical guides 5 symmetrical with respect to axis A, and interact cyclically with the tube 2 to grip and heat seal it along equally spaced cross sections crosswise to axis A.
More specifically, the forming assemblies 6 move along guides 5 from a bottom dead-centre position to a top dead-centre position, and vice versa.
Since the forming assemblies 6 are known and identical to each other, only one of them is described below and shown in the attached drawings.
More specifically, the forming assembly 6 substantially comprises a slide 7 that slides along the respective guide 5. The forming assembly 6 further comprises two jaws 8a, 8b hinged at the bottom to rotate about respective axes F, which in use are horizontal and perpendicular to axis A.
The jaws 8a, 8b are located on opposite sides of the tube 2, and are movable, about respective axes F, between a closed configuration in which they grip the tube 2 (Figure 1), and an open configuration, in which they are detached from the tube 2 (Figure 2).
More specifically, each jaw 8a, 8b comprises a base portion 10 hinged at its bottom end to a bottom portion of the slide 7 about respective axis F, and an arm 11, which interacts with the tube 2, is connected to the portion 10, and extends perpendicularly to axis A when the jaws 8a, 8b are closed onto tube 2, i.e. in the closed configuration.
The jaws 8a, 8b are therefore moved vertically by the slide 7 sliding along the guide 5, and open and close with respect to the tube 2 of packaging material by rotating about respective axes F about which they are hinged to slide 7.
The open-close movement of the jaws 8a, 8b is superimposed on the up-down movement of the slide 7.
The up-down vertical movement and the open-close movement are controlled respectively by a known first actuating device and a known second actuating device, not shown by not being essential to a clear understanding of the present invention.
In particular, the second actuating device provide for rotating jaws 8a, 8b in opposite directions and by the same angle about respective axes F.
The up-down vertical movements of the two assemblies 6 are offset by a half-period: a first assembly 6 travels upwards with the respective jaws in the open configuration while a second assembly 6 travels downwards with the respective jaws in the closed configuration, so that the arms 11 of the first assembly 6 pass between corresponding arms of the second assembly 6 with no interference.
With reference to Figure 4, the assembly 6 also comprises a known sealing device, not shown in the drawings, to heat seal each cross section of the tube 2 of packaging material gripped between the jaws 8a, 8b.
The sealing device comprises a heating member fitted to the arm 11 of the jaw 8a, and which interacts with the tube 2 by means of two active surfaces. The sealing device also comprises two pressure pads fitted to the arm 11 of the jaw 8b, and which cooperate with the respective active surfaces of the heating member to grip and heat seal the tube 2.
The jaw 8b also comprises a cutting member 150 and a front seat 151 which normally houses the cutting member 150.
In detail, the cutting member 150 is normally maintained in a withdrawn rest position in which it is housed completely inside the seat 151 by a helical spring 152. The cutting member 150 is moved by a not-shown actuator into a forward cutting position, in which it projects frontwards from the jaw 8b, engages a groove 153 defined in the sealing device, and cuts the tube 2.
The assembly 6 also comprises (Figures 1, 2 and 4) two forming members 20 facing each other on opposite sides of axis A.
Each forming member 20 comprises a respective forming half-shell 21 that has a main wall 25 and a pair of sidewalls 26 protruding from the main wall 25 towards axis A.
Each forming member 20 further comprises a supporting element 30 intended to be connected to one of the jaws 8a, 8b (in particular to the arm 11) and to which a corresponding forming half-shell 20 is hinged about a rotation axis C. Rotation axis C is crosswise, in particular perpendicular, to axis A.
Each forming member 20 further comprises a pair of arms 54, which protrude from respective sidewalls 26 on respective sides opposite to each other and which are fitted with respective cam follower rollers 55.
Due to the fact that the forming half-shells are hinged to the corresponding supporting element 30 about respective rotation axes C, the forming half-shells 21 are movable between an open position (Figure 2), in which they are kept by a spring 19 (Figure 4), and a closed position (Figure 1), in which they mutually cooperate to delimit a space defining the shape and the volume of packs 3 being formed between the forming half-shells 21.
The forming half-shells 21 are moved from the open position to the closed position by the interaction of the rollers 55 with a not-shown fixed cam extending parallel to axis A.
More specifically, as the assembly 6 moves downwards and the jaws 8a, 8b are closed, the forming half-shells 21 perform a work cycle comprising:

a closing stroke, in which the forming half-shells 21 move towards the tube 2 from the open position to the closed position;
a volume-control stroke, in which the forming half-shells 21 interact with the tube 2 (Figure 1); and
an opening stroke caused by the springs 19, in which the forming half-shells 21 withdraw from the tube 2 and move from the closed position to the open position.

As assembly 6 moves upwards and jaws 8a, 8b are open, the forming half-shells 21 perform a return stroke, in which they are moved away from the tube 2 by spring 19 (Figure 2).
With reference to Figure 5, the supporting element 30 comprises a body 31 provided with a through bore 32. The through bore 32 extends along the rotation axis C and is configured to receive a pin 33 (Figure 4) by means of which the forming half-shell 21 is hinged to the supporting element 30.
The supporting element 30 further comprises a connecting portion 33 by means of which the supporting element is fixed to the corresponding jaw 8a, 8b.
In particular, the connecting portion 33 comprises an opening 34 that receives a bolt 35 (Figure 4) screwed to a threaded hole 36 (Figure 4) of the arm 11 of the corresponding jaw 8a, 8b.
The supporting element 30 further comprises a forming portion 37 configured to interact with the tube 2 to form - together with the forming half-shell 21 - the packs 3.
The forming portion 37 comprises a plurality of grooves 38.
The grooves 38 are parallel to each other.
The grooves 38 are parallel to a longitudinal axis Z of the forming portion 37.
The grooves 38 are substantially parallel to axis A, when the jaws 8a, 8b are in the closed configuration.
Each groove 38 extends transversely to the rotation axis C.
Each groove 38 extends perpendicularly to the rotation axis C.
The groves 38 form a row extending in a direction D parallel to the rotation axis C.
Direction D is perpendicular to longitudinal axis Z.
The forming portion 37 comprises flat ribs 39. Each flat rib 39 is interposed between two adjacent grooves 38.
The flat ribs 39 define a forming surface 40 of the forming portion 37, which interacts with the packaging material.
The supporting element 30 further comprises a slot 41 that is parallel to the grooves 38.
The slot 41 extends in a central area of the forming portion 37 and is parallel to longitudinal axis Z.
The slot 41 is symmetrical with respect to longitudinal axis Z.
The slot 41 has a border 42 that is arranged at a distance d from an edge 43 of the supporting element 30.
A flat portion 44 is defined between the border 42 and the edge 43.
During operation, the flat portion 44 interacts with the tube 2 to form a front edge 108 (Figure 3) of the package 4 that is interposed between the top wall 100 and the front wall 102.
The flat portion 44, together with the flat ribs 39, defines the forming surface 40.
Figure 6 shows another embodiment of the supporting element 30 in which the slot 41 extends up to the edge 43. In this case, the flat portion is not present.
Operation of unit 1 is described below with reference to the first assembly 6 only, and as of the top dead-centre position, in which the jaws 8a, 8b are in the open configuration.
As of the top dead-centre position, jaws 8a, 8b move downwards and interact with respective cam actuating device to move into the closed configuration.
At the same time, the forming half-shells 21 perform their work cycle. In detail, the forming half-shells 21 move towards the tube 2 form the open position to the closed position under the action of not-shown cams.
Once the forming half-shells 21 are closed about the tube 2, the sealing device is activated, and the forming half-shells 21 control the volume and the shape of the pack 3 being formed as the tube 2 is transversally heat-sealed.
Once sealing has been completed, the cutting member 150 is actuated and moved to the forward cutting position, so as to cut the tube 2 along the previously formed transversal sealing band, and so as to separate the formed pack 3 from the remaining part of the tube 2.
At this stage, the forming half-shells 21 move away from the tube 2 under the action of the springs 19 until they reach the open position.
As assembly 6 reaches the bottom dead-centre position, the jaws 8a, 8b move to the open configuration.
Then the assembly 6 travels upwards, while the other assembly 6 travels downwards with the respective jaws in the closed configuration.
The formed packs 3 are conveyed to the folding unit which is arranged downstream of unit 1 so as to form corresponding packages 4.
Owing to the shape of the forming portion, the contact area between the supporting element and the packaging material forming the tube is reduced compared to the known forming members.
This allows to correspondingly reduce the adhesion of the packaging material (in particular of the outer layer of the packaging material that is made of heat-seal plastic material, for example polyethylene) to the forming surface of the supporting element. In this way, when the forming half-shells close on the tube, the packaging material can easily slide on the forming portion and be properly positioned with respect to the forming member.
The number of defective packages is, therefore, significantly reduced when compared with the known forming members.
Clearly, changes may be made to the forming member as described and illustrated herein without, however, departing from the scope defined in the accompanying claims.
In particular, the jaws 8a, 8b could be fitted to respective counter rotating chain conveyors which extend on opposite sides of the tube 2.

Claims

A forming member for controlling the volume of packs (3) of pourable food products formed from a tube (2) of packaging material, comprising a forming half-shell (21) and a supporting element (30) supporting said forming half-shell (21), wherein said forming half-shell (21) comprises forming walls (25, 26) adapted to interact with said tube (2) and wherein said supporting element (30) comprises a connecting portion (33) intended to be connected to a jaw (8a, 8b) of a packaging machine and a forming portion (37) intended to interact with said tube (2) to form said packs (3), characterized in that said forming portion (37) comprises a plurality of grooves (38).
A forming member according to claim 1, wherein said grooves (38) are parallel to each other.
A forming member according to claim 1, or 2, wherein said grooves (38) are parallel to a longitudinal axis (Z) of said forming portion (37).
A forming member according to any one of the preceding claims, wherein said forming half-shell (21) is hinged to said supporting element (30) about a rotation axis (C), each of said grooves (38) extending transversely to said rotation axis (C).
A forming member according to claim 4, wherein each of said groves (38) extends perpendicularly to said rotation axis (C).
A forming member according to claim 4, or 5, wherein said grooves (38) form a row extending in a direction (D) parallel to said rotation axis (C).
A forming member according to any one of the preceding claims, wherein said forming portion (37) comprises flat ribs (39).
A forming member according to claim 7, wherein each flat rib (39) is interposed between two adjacent grooves (38).
A forming member according to claim 7, or 8, wherein said flat ribs (39) define a forming surface (40) of said forming portion (37) intended to interact with said tube (2).
A forming member according to any one of the preceding claims, wherein said supporting element (30) further comprises a slot (41) that is parallel to said grooves (38).
A forming member according to claim 10, wherein said slot (41) extends in a central area of said forming portion (37) and is parallel to a longitudinal axis (Z) of said forming portion (37).
A forming member according to claim 10, or 11, wherein said slot (41) has a border (42) that is arranged at a distance (d) from an edge (43) of said supporting element (30), a flat portion (44) being defined between said border (42) and said edge (43).
A forming member according to any one of claims 10 to 12, as appended to claim 9, wherein said flat portion (44) defines said forming surface (40), together with said flat ribs (39).
A forming member according to claim 10, or 11, wherein said slot (41) extends up to an edge (43) of said supporting element (30).
A forming unit for producing packs (3) of pourable food products formed from a tube (2) of packaging material comprising a first jaw (8a) and a second jaw (8b) movable cyclically between a closed configuration, in which they grip and seal said tube (2), and an open configuration, in which they are detached from said tube (2), at least one of said first jaw (8a) and said second jaw (8) having a forming member according to any one of claims 1 to 14.