Unit and method for forming tubes for producing sealed packages starting from a sheet of packaging material

Abstract

We describe a unit (1) configured to form a tube (2) for producing a sealed package (3) starting from a sheet (4) of packaging material having a pre-attached opening device (5), the unit (1) comprising at least one guide assembly (10) configured to interact with the sheet (4) of packaging material to gradually fold the sheet (4) into a tubular shape, the guide assembly (10) comprising a plurality of folding rollers (11, 13), the plurality of folding rollers (11, 13) defining a passage (50) for the sheet (4) of packaging material and each having a side wall (11 a) configured to contact and cooperate with the sheet (4) of packaging material to control the folding of the sheet (4), wherein the folding rollers (11, 13) comprise at least one folding roller (13) having at least one recess in its side wall (11 a), the recess defining a slot (14) configured to be engaged by the opening device (5).

Description

[Technical Field]

[0001] The present invention relates to a unit configured to form, starting from a sheet of packaging material with a pre-attached opening device, in particular a sheet of packaging material with a pre-formed opening device, a tube for producing sealed packages, preferably packages containing pourable products, in particular pourable food products.

[0002] The invention further relates to a method for forming a tube for producing a sealed package, preferably a package containing a pourable product, in particular a pourable food product, starting from a sheet of packaging material with a pre-affixed opening device, in particular a sheet of packaging material with a pre-formed opening device. [Background technology]

[0003] As is commonly known, many pourable foods, such as fruit juice, UHT (ultra-high temperature processed) milk, wine, and tomato sauce, are sold in packages made from sterilized packaging material.

[0004] A typical example is the parallelepiped-shaped package for pourable food products known as Tetrabrik Aseptic®, which is made by folding and sealing a laminated web of packaging material. The packaging material has a multi-layer structure, with a base layer, e.g., made of paper, covered on both sides with layers of heat-sealable plastic material, such as polyethylene. In the case of aseptic packages for long-life products such as UHT milk, the packaging material also comprises a layer of oxygen barrier material, e.g., aluminum foil, which is laminated to the layer of heat-sealable plastic material and covered with another layer of heat-sealable plastic material, which ultimately forms the inner surface of the package that comes into contact with the food.

[0005] Such packages are typically produced in a fully automated packaging assembly, where a continuous tube is formed from a web of packaging material unwound from a reel and fed to the assembly. The sheet of packaging material is sterilized within the assembly by applying a chemical sterilant, such as a hydrogen peroxide solution. After sterilization is complete, the chemical sterilant is removed from the surface of the packaging material and evaporated, for example, by heating. The thus-sterilized web is then maintained in a closed, sterile environment, folded and longitudinally sealed to form a tube, which is fed along a vertical forward direction.

[0006] To complete the forming operation, the tube is filled from the top with sterile food product, sealed by known forming and sealing units, and then cut along equally spaced cross sections.

[0007] This results in a pillow pack having a longitudinal sealing band, an upper lateral sealing band, and a lower lateral sealing band.

[0008] Known packaging assemblies typically include a folding unit that is configured to receive a pillow pack to form a fully folded, finished package.

[0009] To form the tube, the web of packaging material is fed through a plurality of guide assemblies that interact with the packaging material to gradually fold the packaging material from a sheet form into a tube form.

[0010] The guide assemblies are arranged in series and include respective folding members defining a number of forced passages such that the cross-sectional shape of the packaging material gradually changes from a C-shape to a substantially circular shape.

[0011] In particular, each guide assembly includes a plurality of folding rollers that define folding members and rotate about axes of rotation that are disposed in a common plane, typically a horizontal plane.

[0012] When interacting with the folding rollers, a first longitudinal edge of the sheet of packaging material gradually approaches and then overlaps a second longitudinal edge of the sheet of packaging material opposite the first longitudinal edge, until one of the two longitudinal edges overlaps the other in a radial direction relative to the tube axis.

[0013] The first longitudinal edge and the second longitudinal edge are then sealed, for example heat sealed, to one another to form a longitudinal sealing band along the tube, i.e., substantially parallel to the tube axis.

[0014] At this point, the tube can be filled with an injectable product and then formed, transversely sealed and cut to obtain the pillow packs described above.

[0015] To open the above mentioned packages, various solutions have been proposed, including the use of opening devices made of plastic material.

[0016] According to a first solution, it is known that the opening device is molded, for example injection molded, directly into a so-called pre-laminated hole, i.e. a hole formed only by a base layer, and is covered by a lamination process with another lamination of packaging material comprising a layer of gas barrier material.

[0017] In other words, molten plastic material is molded, in particular injection molded, onto and through the cover portions of the pre-laminated holes made in such a laminate.

[0018] According to an alternative solution, such a cover portion may be defined by a patch attached to the packaging material to close the hole formed in this case through the entire thickness of the packaging material.

[0019] According to an alternative solution, a hole is formed through the entire thickness of the packaging material, in particular a hole is punched, and an opening device is subsequently molded therein.

[0020] Thus, in the above solutions, the sheet of packaging material is already provided with a pre-affixed opening device before being forced through the guide assembly.

[0021] During the formation of a tube starting from a sheet of packaging material with a pre-attached opening device, the opening device may interfere with and collide with one of the folding rollers, especially when the folding roller is within the path of the opening device.

[0022] A known solution is to remove such folding rollers, thereby freeing up the passage of the opening device through the guide assembly.

[0023] However, for some types of packages, for example small packages such as single-serving size packages, the above solutions have some drawbacks.

[0024] In fact, when the first longitudinal edge is overlapped with the second longitudinal edge, an overlap area is defined, and it is very important to control the extent, i.e., width, of the overlap area to ensure good longitudinal sealing of the tube and an appropriate weight for the resulting package.

[0025] The applicant has observed that if the ratio between the diameter of the tube and the size of the opening device is very small, removing one of the folding rollers may compromise the optimal overlap of the first longitudinal edge and the second longitudinal edge of the sheet of packaging material.

[0026] In fact, the removal of one folding roller can result in a radial bulge of the tube in the area of ​​the removed folding roller.

[0027] Furthermore, since the operations of forming the tube and sealing the longitudinal seal are performed sequentially, it is very important that the extent of the overlap area remains as constant as possible during the working cycle of the packaging assembly. Summary of the Invention [Problem to be solved by the invention]

[0028] It is therefore an object of the present invention to provide a unit configured to form a tube for producing sealed packages, starting from a sheet of packaging material having a pre-attached opening device, designed to overcome at least one of the above-mentioned drawbacks in a simple and cost-effective manner. [Means for solving the problem]

[0029] This object is achieved by a unit as claimed in claim 1.

[0030] A further object of the present invention is to provide a method for forming a tube for producing sealed packages, starting from a sheet of packaging material with a pre-attached opening device, which makes it possible to overcome at least one of the above-mentioned drawbacks in a simple and cost-effective manner.

[0031] This object is achieved by a method as claimed in claim 11.

[0032] Non-limiting embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0033] [Figure 1] FIG. 1 is a perspective view, with some parts removed for clarity, of a packaging assembly for producing sealed packages, comprising a unit configured to form a tube for producing such packages starting from a sheet of packaging material according to the invention. [Figure 2] FIG. 2 is a larger perspective view of the unit of FIG. 1 with some parts removed for clarity. [Figure 3] FIG. 3 is a partial cross-sectional side view of the unit of FIG. 2 with parts removed for clarity. [Figure 4]FIG. 3 is a partial cross-sectional top view of the unit of FIG. 2 with parts removed for clarity. DETAILED DESCRIPTION OF THE INVENTION

[0034] With reference to Figure 1, the number 1 indicates as a whole a unit arranged to form, starting from a sheet 4 of web-like packaging material with a pre-attached opening device 5, in particular a sheet 4 of packaging material with a pre-formed opening device 5, a tube 2 for producing a sealed package 3, preferably a package 3 containing a pourable product, in particular a pourable food product, such as pasteurised or UHT milk, fruit juice, wine, pulses.

[0035] The unit 1 is part of a known packaging assembly 100 for continuously producing packages 3 from a sheet 4 of packaging material, the sheet 4 being unwound from a reel 6 and fed along a forming path P.

[0036] The packaging material has a multi-layer structure (not shown) and comprises a layer of fibrous material such as paper covered on each side with a layer of heat-sealable plastic material such as polyethylene.

[0037] In the case of an aseptic package 3 for a long shelf life product such as UHT milk, the packaging material also comprises a layer of gas and light barrier material such as aluminium foil or ethylene vinyl alcohol (EVOH) film, which is laminated to a layer of heat seal plastic material and covered with another layer of heat seal plastic material, which forms the inner surface of the package 3 that will ultimately contact the pourable product.

[0038] After being unwound from the reel 6 and before entering the unit 1, the sheet 4 of packaging material is sterilized by application of a chemical sterilant, such as a hydrogen peroxide solution, and is provided with a plurality of opening devices 5 (Figures 2, 3 and 4). After sterilization is complete, the chemical sterilant is removed from the surface of the packaging material and evaporated, for example by heating.

[0039] According to this non-limiting embodiment, the opening device 5 is made of a plastic material that is injection molded into the sheet 4 of packaging material by a known molding device (not shown) located downstream of the reel 6 and upstream of the unit 1 along the forming path P.

[0040] In particular, the opening devices 5 are formed in the sheet 4 of packaging material at substantially the same distance L, in particular the same linear distance L, from each other along a substantially straight adhesive band.

[0041] Here, the term "substantially" is used herein to take into account normal tolerances that may exist between the components of the unit 1 and the packaging assembly 100.

[0042] As can be seen in Figure 1, a sheet 4 of packaging material is fed along a forming path P by guide members 7, such as rollers.

[0043] The packaging assembly 100 further comprises a known forming and sealing means, such as a jaw-type unit (not shown), located downstream of unit 1 and configured to grip, form, transversely seal and cut the tube 2 along equally spaced cross sections to obtain pillow packs 3a.

[0044] Such pillow packs 3 a are then fed to a folding unit (not shown) configured to fold them to form finished packages 3 .

[0045] The unit 1 comprises a folding assembly 8 for gradually folding a sheet 4 of packaging material.

[0046] The folding assembly 8 comprises a plurality of guide assemblies 10, in the preferred embodiment shown two, arranged in succession along the forming path P and configured to interact with the sheet 4 of packaging material to fold the sheet 4 gradually into a tubular shape, thereby obtaining the tube 2.

[0047] In particular, each guide assembly 10 includes a plurality of folding rollers 11 rotatably mounted on the corresponding guide assembly 10 about respective axes of rotation, and configured to define a passage 50 (FIG. 4) for the sheet 4 of packaging material, i.e., the tube 2 being formed, and to interact with the sheet 4 of packaging material.

[0048] In particular, each folding roller 11 has a side wall 11 a which is configured to contact and cooperate with the sheet 4 of packaging material to control the folding of the sheet 4 .

[0049] More particularly, as the sheet of packaging material 4 is pulled through the passageway 50 by action of the jaw-type unit during use, the side walls 11a of the folding rollers 11 interact with the sheet of packaging material 4 to shape the sheet of packaging material 4 into the tube 2.

[0050] More precisely, according to a known method not described in detail, the folding rollers 11 are configured to come into contact with and cooperate with the sheet 4 of packaging material to overlap a first longitudinal edge 4a of the sheet 4 with a second longitudinal edge 4b ​​of the sheet 4 opposite the first longitudinal edge 4a, thereby defining an overlap area 12 between the first longitudinal edge 4a and the second longitudinal edge 4b.

[0051] In other words, the folding rollers 11 form the tube 2 so that the first longitudinal edge 4a is located outside the second longitudinal edge 4b ​​relative to the axis A of the tube 2 (FIG. 4).

[0052] The unit 1 further comprises a sealing station (not shown) comprising sealing means, preferably heating means, configured to heat the first longitudinal edge 4a and locally melt the polyethylene layer at the first longitudinal edge 4a.

[0053] Heat is transferred by conduction from the first longitudinal edge 4a to the second longitudinal edge 4b, causing local melting of the polyethylene layer at the second longitudinal edge 4b.

[0054] The first longitudinal edge 4a and the second longitudinal edge 4b ​​are then pressed together to obtain a longitudinal seal substantially parallel to the axis A.

[0055] At this point the tube 2 can be filled, preferably from the top, with pourable product.

[0056] As can be seen in the accompanying drawings, the path 50 defined by the folding rollers 11 is coaxial with the axis A.

[0057] Preferably, the rotation axes of the folding rollers 11 of one guide assembly 10 are arranged in a common plane.

[0058] In particular, the two guide assemblies 10 are arranged on different planes arranged successively along the forming path P.

[0059] In the illustrated embodiment, such planes are horizontal and parallel to one another, and axis A is vertical.

[0060] Thus, in use, the sheet of packaging material 4 first interacts with the upper guide assembly 10, causing the first longitudinal edge 4a to approach the second longitudinal edge 4b, thereby folding the sheet of packaging material 4 into a substantially C-shape.

[0061] The folded sheet of packaging material 4 then interacts with a lower guide assembly 10 which determines the creation of an overlap region 12 and folds the C-shaped sheet of packaging material 4 into a tubular shape.

[0062] In light of the above, folding rollers 11 surround the sheet 4 of packaging material during folding of the sheet 4 of packaging material and thus during formation of the tube 2 .

[0063] Since the sheet 4 of packaging material is provided with an opening device 5 pre-attached along the attachment band, such opening device 5 may collide with one of the folding rollers 11 that surround the sheet 4 of packaging material and define the passage 50.

[0064] One solution to this problem involves removing the folding rollers 11 in the path of the opening device 5 through the passage 50.

[0065] However, as mentioned above, the applicant has observed that in the case of small sized packages 3, i.e. in the case of small diameter tubes 2, such removal may impair the optimal overlap of the first longitudinal edge 4a onto the second longitudinal edge 4b ​​in the overlap region 12.

[0066] Advantageously, the folding rollers 11 comprise at least one folding roller 13 having at least one recess in its side wall 11a, which recess defines a slot 14 configured to be engaged by the opening device 5.

[0067] Preferably, the folding roller 13 has a plurality of slots 14 in its sidewall 11a to define alternating solid and void portions in said sidewall 11a, each void portion being defined by one respective slot 14.

[0068] In particular, the folding roller 13 defines a toothed wheel 15 with a plurality of teeth 16 that define the solid portion mentioned above.

[0069] Additionally, teeth 16 are configured to selectively engage opening device 5 to rotationally drive wheel 15 with movement of sheet 4 of packaging material through passageway 50 .

[0070] In light of the above, the sheet 4 of packaging material drives or rotates the wheels 15 or folding rollers 13 by the opening device 5 engaging the respective slots 14 and meshing with the respective teeth 16 .

[0071] More specifically, the opening device 5 engages with each side of the teeth 16, as shown particularly in FIG.

[0072] Furthermore, the teeth 16, and in particular the upper surfaces of the teeth 16, define respective portions of the side walls 11a of the folding rollers 13 that are configured to contact and cooperate with the sheet 4 of packaging material, as shown in particular in Figures 2 and 3.

[0073] Preferably, the folding roller 13 is rotatable about an axis of rotation B which is arranged in the same common plane as the axes of rotation of the other folding rollers 11 of the same guide assembly 10, i.e. the lower guide assembly 10.

[0074] In particular, axis B is perpendicular to axis A.

[0075] The presence of folding rollers 13, i.e. wheels 15, makes it possible to achieve an optimal overlap of the first longitudinal edge 4a onto the second longitudinal edge 4b ​​in the overlap region 12, since the alternating arrangement of solid and void portions, i.e. teeth 16 and slots 14, provides radial support for the sheet 4 of packaging material while at the same time allowing the free passage of the opening device 5 through the passage 50.

[0076] In other words, the teeth 16 prevent the sheet 4 of packaging material, i.e. the tube 2 being formed, from bulging, i.e. from being displaced radially relative to the axis A, which could impair the optimal overlap obtained in the overlap region 12.

[0077] At the same time, each slot 14 provides space for an opening device 5 pre-affixed to the sheet 4 of packaging material to pass freely through the passage 50, thereby avoiding radial collisions.

[0078] According to the preferred embodiment shown, only one of the guide assemblies 10, in particular the lower guide assembly 10, is provided with one folding roller 13.

[0079] Thus, the upper guide assembly 10 has one folding roller 11 removed to allow the opening device 5 to pass freely through the corresponding passage 50 .

[0080] As mentioned above, the opening device 5 presses against each tooth 16 causing the wheel 15 to rotate.

[0081] Advantageously, therefore, the folding rollers 13, ie the wheels 15, are idle rollers, ie are passively driven in rotation.

[0082] Furthermore, the above-described configuration provides a self-synchronizing meshing: indeed, if the folding rollers 13 accumulate a certain amount of delay with respect to the nominal meshing of the teeth 16 with the opening device 5, the opening device 5 itself acts on the respective teeth 16, in particular on the aforementioned lateral portions of the teeth 16, thereby ensuring self-synchronization.

[0083] It is preferred to provide multiple slots 14 in the folding rollers 13 to ensure the shortest delay between the slots 14 and the opening device 5 and therefore the fastest delay recovery.

[0084] Preferably, the distance between two successive slots 14 or two successive teeth 16 measured around the circumference of the side wall 11a of the folding roller 13 is equal to the quotient of the distance L divided by an integer.

[0085] It is specified herein that the aforementioned distance is a curved distance measured on the circumference of the folding roller 13, i.e. the distance is defined by a circular arc.

[0086] Therefore, the folding roller 13 may have any number of slots 14 and teeth 16, provided that the distance between two consecutive slots 14 or two consecutive teeth 16 measured around the circumference of the side wall 11a of the folding roller 13 is equal to the quotient of the distance L divided by an integer.

[0087] According to an embodiment not shown, the unit 1 may comprise an actuation device (not shown), such as a motor, operably coupled to the folding rollers 13 and configured to selectively control the rotation of the folding rollers 13 about the axis B. For example, the actuation device may control the rotation of the folding rollers 13 to restore a delay in the meshing of the teeth 16 with the opening device 5.

[0088] Preferably, the slots 14 are equally spaced from one another along the sidewall 11a, and therefore the teeth 16 are also equally spaced from one another along the sidewall 11a.

[0089] Therefore, the solid portions and void portions alternate at a regular interval.

[0090] The operation of unit 1 is as follows: Starting with a sheet 4 of packaging material already interacting with upper guide assembly 10 and advancing towards lower guide assembly 10 where folding rollers 13 are located.

[0091] At this point, the sheet of packaging material 4 interacts with folding rollers 11 and 13 of lower guide assembly 10 and advances through path 50 .

[0092] Accordingly, the opening device 5 engages in turn with the slots 14 of each of the folding rollers 13 and meshes with the teeth 16 of the folding rollers 13, thereby driving the folding rollers 13, i.e. the wheels 15, to rotate about the axis B.

[0093] In this way, an overlap between the first longitudinal edge 4a and the second longitudinal edge 4b ​​is obtained and maintained in the overlap area 12, while the opening device 5 can pass freely through the passage 50 without hindrance.

[0094] A tube 2 is thereby formed, which is sealed longitudinally and filled from above with a pourable product in a known manner not described in detail.

[0095] The tube 2 is then fed to a jaw-type unit located downstream of unit 1 where it is formed, transversely sealed and cut along equally spaced cross sections to obtain pillow packs 3a.

[0096] Such pillow packs 3 a are then fed to a folding unit configured to fold them into finished packages 3 .

[0097] The above operations occur continuously throughout the entire working cycle of the packaging assembly 100.

[0098] The advantages of the unit 1 according to the invention will be apparent from the above description.

[0099] In particular, the configuration of the folding rollers 13, i.e. wheels 15, allows for an optimal overlap of the first longitudinal edge 4a onto the second longitudinal edge 4b ​​in the overlap region 12, since the alternating arrangement of solid and void portions, i.e. teeth 16 and slots 14, provides radial support for the sheet 4 of packaging material while at the same time allowing the free passage of the opening device 5 through the passage 50.

[0100] In other words, the teeth 16 prevent the sheet 4 of packaging material, i.e. the tube 2 being formed, from expanding, i.e., being radially displaced relative to the axis A, thereby ensuring that the extension area of ​​the overlap region 12 remains as constant as possible during the working cycle of the packaging assembly 100.

[0101] Thus, a unit 1 is provided for the optimal production of small packages 3 starting from a sheet 4 of packaging material having a pre-attached opening device 5 .

[0102] Obviously, modifications can be made to unit 1 as described herein without departing from the scope of protection defined in the appended claims.

Claims

1. A unit (1) configured to form a tube (2) for producing a sealed package (3) starting from a sheet (4) of packaging material having a pre-attached opening device (5), the unit comprising at least one guide assembly (10) configured to interact with said sheet (4) of packaging material and gradually fold said sheet (4) into a tubular shape, A unit (1) wherein the guide assembly (10) comprises a plurality of folding rollers (11, 13) defining a guide path (50) for the sheet (4) of packaging material, each having a side wall (11 a) configured to contact and cooperate with the sheet (4) of packaging material to control folding of the sheet (4), the folding rollers (11, 13) comprise at least one folding roller (13) having at least one recess in the side wall (11a), the recess defining a slot (14) configured to be engaged by the opening device (5); The unit (1), wherein the at least one folding roller (13) has a plurality of the slots (14) in the side wall (11a) to define alternating solid and void portions in the side wall (11a).

2. 2. A unit as claimed in claim 1, wherein said slots (14) are equally spaced from one another along said side wall (11a).

3. 3. The unit of claim 1 or 2, wherein the at least one folding roller (13) defines a toothed wheel (15) having a plurality of teeth (16) defining the solid portion and configured to selectively engage the opening device (5).

4. 4. A unit as claimed in claim 3, wherein said teeth (16) define a portion of said side wall (11a) of said at least one folding roller (13) configured to contact and cooperate with said sheet (4) of packaging material.

5. 5. A unit according to any one of claims 1 to 4, wherein the distance between two consecutive slots (14) or two consecutive solid portions measured around the circumference of the side wall (11a) of the at least one folding roller (13) is equal to an integer division of the distance (L) between two consecutive opening devices (5) in the sheet (4) of packaging material.

6. 6. A unit according to any one of claims 1 to 5, wherein the folding rollers (11) are rotatable about a first axis of rotation arranged in a common plane and the at least one folding roller (13) is rotatable about a second axis of rotation (B) arranged in the same common plane.

7. 7. The unit according to any one of claims 1 to 6, further comprising an actuation device operatively coupled to the at least one folding roller (13) and configured to selectively control the rotation of the at least one folding roller (13) about its own axis of rotation (B).

8. A unit according to any one of the preceding claims, wherein said guide channel (50) has a longitudinal axis and said at least one folding roller (13) has an axis of rotation perpendicular to said longitudinal axis.

9. 9. A unit according to any one of claims 1 to 8, wherein the folding rollers (11, 13) are configured to contact and cooperate with the sheet (4) of packaging material to overlap a first longitudinal edge (4a) of the sheet (4) with a second longitudinal edge (4b) of the sheet (4) opposite the first longitudinal edge (4a) to define an overlap region (12) of the first longitudinal edge (4a) and the second longitudinal edge (4b).

10. 1. A method for forming a tube (2) for producing a sealed package (3), starting from a sheet (4) of packaging material with a pre-attached opening device (5), comprising: a) advancing said sheet (4) of packaging material through a guide passage (50); b) providing a plurality of folding rollers (11, 13) defining said guide passage (50) and having respective side walls (11 a), said folding rollers (11, 13) comprising at least one folding roller (13) having at least one recess in said side wall (11 a), said recess defining a slot (14); c) by means of said side walls (11a) in contact with and cooperating with said sheet (4) of packaging material, gradually folding said sheet (4) into a tubular shape; d) engaging said slot (14) of said at least one folding roller (13) with said opening device (5); Including, The at least one folding roller (13) has a plurality of slots (14) in the side wall (11a), and the method comprises: e) engaging said opening device (5) into said slot (14); further comprising: How to do it.

11. f) driving said at least one folding roller (13) into rotation by carrying out said advancing step a) and by said engaging step e). The method of claim 10 further comprising:

12. g) driving said at least one folding roller (13) in rotation about its axis of rotation (B) by means of an actuation device.

12. The method of claim 10 or 11, further comprising:

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