FORMING UNIT FOR FORMING A TUBE FROM A WEB OF PACKAGING MATERIAL, AN APPARATUS FOR PRODUCING A SEALED TUBE PROVIDED WITH SAID FORMING UNIT, A PACKAGING MACHINE WITH SAID APPARATUS AND A METHOD TO OPERATE SAID APPARATUS

Abstract

 It is described a forming unit (9) for folding a web (4) of packaging material into a tube (10) and superimpose a first lateral portion (4A) of the web (4) of packaging material to a second lateral portion (4B) of the web (4) of packaging material with a number of forming devices (12) placed along a conveying path (P) in succession; wherein each forming device (12) comprises a respective forming ring (13) surrounding the web (4) of packaging material being folded; and a number of supporting elements (18) configured to contact and maintain in a predetermined position said first and/or the second lateral portion (4A, 4B), wherein the number of supporting elements (18) are arranged in a fixed position with respect to the forming devices (12).

Description

TECHNICAL FIELD

[0001] The present invention relates to a forming unit for forming a tube from a web of packaging material, an apparatus for producing a sealed tube provided with said forming unit, a packaging machine with said apparatus and a method to operate said apparatus.

BACKGROUND ART

[0002] As it is known, many liquid or pourable food products, such as for example pasteurized or long-life (UHT) milk, tomato sauce, wine, fruit juice are sold in packages made of sterilized packaging material.

[0003] Packages of this sort are normally produced with automatic packaging machines, which feed a web of packaging material through a sterilizing unit by means of known guiding elements (like for example rollers) for sterilizing the web of packaging material alternatively by means of chemical sterilization in a sterilizing bath (e.g. by applying a chemical sterilizing agent, such as a hydrogen peroxide solution) or by means of physical sterilization (e.g. by means of an electron beam).

[0004] The packaging machine further comprises a folding unit arranged downstream of the sterilizing unit, extending substantially vertically and designed to fold the web of packaging material for producing a continuous tube. Inside the folding unit, the web of packaging material is folded from a continuous planar shape to a continuous tubular shape with a vertical axis. The web of packaging material with a planar shape is folded into a cylinder that is successively subdivided into a plurality of pillow packs which are subjected to successive mechanical folding operations to obtain the finished sealed packages.

[0005] The folding unit is preferably arranged within a fixed structure in which the web of packaging material is maintained in a sterile-air environment. The folding unit further comprises a number of folding devices placed in succession (one after the other): by interacting with the folding devices, opposite lateral portions (or edges) of the web of packaging material are placed one on top of the one another so as to form the tube and so as to define an overlapping area.

[0006] The packaging machine further comprises a sealing unit for sealing overlapping lateral portions of the web of packaging material to finally obtain a fluid-tight longitudinal seal in the tube. Typically, the sealing unit is arranged between two folding devices along the conveying path and comprises a heating device and a number of supporting devices, at least partially connected to the heating device, and realized to contact and maintain in a predetermined position at least part of the web of packaging material. The assembly made by the heating element and the supporting devices connected thereto is movable between an operating position wherein the heating element is interposed between the two overlapping lateral portions and a rest position wherein the assembly is at a distance from the web of packaging material.

[0007] When the advancement of the web of packaging material along the conveying path is interrupted, the assembly made by the heating element and the supporting devices is moved from the operating position to the rest position to avoid directing too much heat onto the web of packaging material. Even though the known folding and sealing units operate satisfyingly well, a desire is felt for improving the known units, in particular the interruption of operation that are influenced by the movement of the heating element. For example, the movement of the heating element between the operating position and the rest position may lead (after or during the movement) to arranging the heating element in a non-ideal position due to mechanical reasons or into contact with the web of packaging material.

DISCLOSURE OF INVENTION

[0008] The object of the invention is to provide forming unit for forming a tube from a web of packaging material addressing the drawbacks described above and, in particular, being easy and economical to be manufactured.

[0009] A further object of the invention is to provide an apparatus for producing a sealed tube addressing the drawbacks described above and, in particular, being easy and economical to be manufactured.

[0010] A further object of the invention is to provide a packaging machine addressing the drawbacks described above and, in particular, being easy and economical to be manufactured.

[0011] Finally, a further object of the invention is to provide a method to operate an apparatus for producing a sealed tube addressing the drawbacks described above and, in particular, being easy and economical to be implemented.

[0012] According to the invention, there are provided a forming unit for forming a tube from a web of packaging material, an apparatus for producing a sealed tube provided with said forming unit, a packaging machine with said apparatus and a method to operate said apparatus according to the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] A 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, with parts removed for clarity, of a packaging machine for producing packages from a packaging material, in accordance with the present invention;
• Figure 2 is a schematic side view of the packaging machine of Figure 1; and
• Figure 3 is a perspective view, with parts removed for clarity, of a forming unit for forming a tube from a web of packaging material in accordance with the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0014] Figures 1 and 2 disclose, as a whole, a packaging machine 1 for continuously producing sealed packages, containing a pourable food product, such as for example pasteurized or long-life (UHT) milk, tomato sauce, wine, fruit juice. The sealed packages are obtained from a packaging material unwound from a reel 3 and fed along a conveying path P. When unwound from the reel 3, the packaging material has the shape of a continuous planar web 4 of packaging material.

[0015] Typically, the packaging material has a multi-layer structure. More specifically, the packaging material may comprise at least a layer of fibrous material, such as for example a paper or cardboard layer, and at least two layers of heat-seal plastic material, e.g. polyethylene, with the layer of fibrous material interposed between them. One of these two layers of heat-seal plastic material may define the inner face of the packages eventually contacting the pourable product.

[0016] According to some possible non-limiting embodiments, the packaging material may also comprise a layer of gas-and light-barrier material, e.g. aluminum foil or ethylene vinyl alcohol (EVOH) film, which, in particular, is arranged between one of the layers of heat-seal plastic material and the layer of fibrous material. Preferably, the packaging material may also comprise a further layer of heat-seal plastic material interposed between the layer of gas- and light-barrier material and the layer of fibrous material.

[0017] The web 4 of packaging material is fed to a sterilizing unit 5 by means of guiding elements 6, in particular by a number of rollers 6 (one of said rollers is illustrated in figure 2). The sterilizing unit 5 has a sterilizing bath 7, in which a chemical sterilizing agent, such as a hydrogen peroxide solution, is applied to the web 4 of packaging material. The web 4 of packaging material is fed through the sterilizing unit 5 by means of known guiding elements 8, like for example rollers 8 or similar elements.

[0018] The packaging machine 1 further comprises a forming unit 9 arranged downstream of the sterilizing unit 5 along the conveying path P. The forming unit 9 extends substantially vertically along the conveying path P for producing a continuous tube 10. In particular, inside the forming unit 9, the web 4 of packaging material is folded from a continuous planar shape to a continuous tubular shape with a longitudinal axis Y. In particular, the longitudinal axis Y is arranged along a vertical direction.

[0019] The forming unit 9 is defined within a fixed structure 11 in which the web 4 of packaging material is maintained in a sterile-air environment. The forming unit 9 further comprises a number of forming/folding devices 12 placed along the conveying path P in succession (one after the other).

[0020] Advantageously, each of said folding devices 12 may comprise a ring-like shape, e.g. at least partially enclosing the web 4 of packaging material. For example, the folding device 12 may comprise a forming ring 13 surrounding the web 4 of packaging material. The supporting device 12 may be configured for supporting a number of rollers 14 cooperating to fold the web 4 of packaging material.

[0021] In particular, the forming unit 9 comprises a (first) folding device 12A and a (second) folding device 12B placed along the conveying path P in succession (one after the other) carried by the fixed structure 11, and interacting with the web 4 of packaging material to fold the web 4 of packaging material gradually into a tube (cylinder) and superimpose a (first) lateral portion 4A of the web 4 of packaging material to a (second) lateral portion 4B of the web 4 of packaging material, opposite the (first) lateral portion 4A, to form the continuous tube 10.

[0022] The folding device 12B is placed downstream of the folding device 12A along the conveying path P.

[0023] With particular reference to figures 1 and 4, the first folding device 12A comprises the first folding ring 13A supporting a plurality of first folding rollers 14A; said first folding rollers 14A have respective axes perpendicular to the axis Y. Said first folding rollers 14A have respective lateral surfaces with concave shape (i.e. the web 4 of packaging material encounters a diameter at the ends greater than a diameter at the center of the first folding rollers 14A). The lateral surfaces of the first folding rollers 14A define a first compulsory passage for the web 4 of packaging material being folded.

[0024] Similarly, the second folding device 12B comprises the second folding ring 13B supporting a plurality of second folding rollers 14B; said second folding rollers 14B have respective axes perpendicular to the axis Y. Said second folding rollers 14B have respective lateral surfaces with concave shape (i.e. the web 4 of packaging material encounters a diameter at the ends greater than a diameter at the center of the second folding rollers 14B). The lateral surfaces of the second folding rollers 14A define a second compulsory passage for the web 4 of packaging material being folded.

[0025] The first compulsory passage and the second compulsory passage are different in section. More in detail, the web 4 of packaging material has a substantially C-shape in the area of the first folding device 12A and a substantially circular shape in the area of the second folding device 12B. A gap is defined between the lateral portion 4A and the lateral portion 4B of the web 4 of packaging material which decreases gradually in section along the conveying path P from the first compulsory passage to the second compulsory passage.

[0026] The packaging machine 1 comprises a sealing unit 15 (of the known type and shown schematically in figures 1 and 3) for sealing overlapping lateral portions 4A, 4B of the web 4 of packaging material to obtain a fluid-tight longitudinal seal in the tube 10. The sealing unit 15 is arranged downstream of the first folding devices 12A along the conveying path P. Advantageously, the sealing unit 15 is interposed between the two folding devices 12A, 12B.

[0027] The sealing unit 15 comprises a heating element 16. According to a first embodiment, the heating element 16 comprises an induction heating element 16 for inductively heating the internal surface of the lateral portion 4A to be superimposed the facing surface of the second lateral portion 4B. The internal surface of the lateral portion 4A is the surface facing the second lateral portion 4B.

[0028] According to a second embodiment, the heating element 16 comprises a hot air heating element 16 having a number of nozzles for directing hot air onto the internal surface of the lateral portion 4A to be superimposed the facing surface of the second lateral portion 4B.

[0029] The heating element 16 is supported by an arm carried by the fixed structure 11. The arm and the heating element 16 are mobile; in particular, the arm and the heating element 16 are mobile between an operating position wherein the heating element 16 is interposed between the two lateral portions 4A, 4B and facing the internal surface of the lateral portion 4A and a rest position wherein the heating element 16 is away from the web 4 of packaging material; and vice versa from the rest position to the operating position. More in detail, in the operating position, the heating element 16 is placed in the air gap defined between the two lateral portions 4A, 4B. The heating element 16 is realized for directing heat onto the internal surface of the lateral portion 4A in the operating position.

[0030] Along the conveying path P it is defined a sealing region in correspondence of the sealing unit 15. More in detail, the sealing region is defined along the conveying path P in the area wherein the heating element 16 is interposed between the two lateral portions 4A, 4B the web 4 of packaging material.

[0031] The forming unit 9 further comprises a number of supporting elements 18, each of which is realized to contact and maintain in a predetermined position at least part of the web 4 of packaging material.

[0032] The supporting elements 18 may be positioned upstream of or at a heating area, wherein the web 4 of packaging material is heated.

[0033] According to a first embodiment, the supporting elements 18 comprise rollers. According to a second embodiment, the supporting elements 18 comprise conical shaped elements (so called "fingers").

[0034] Advantageously, the supporting elements 18 are realized to contact and maintain in a predetermined position the external surface of the first lateral portion 4A (or edge) of the web 4 of packaging material to be heated.

[0035] Alternatively, the supporting elements 18 are advantageously realized to contact and maintain in a predetermined position at a predetermined distance from heat the external surface of the second lateral portion 4B (or edge) of the web 4 of packaging material. The external surface of second lateral portion 4B is the surface facing the first lateral portion 4A.

[0036] More in detail, supporting elements 18 comprise at least a superior supporting element 18A. Said superior supporting element 18A is placed in the area of the folding device 12A.

[0037] According to a possible embodiment, the superior supporting element 18A comprises folding rollers 14A which are realized to contact and maintain in a predetermined position at least part of the web 4 of packaging material. In particular, folding rollers 14A are realized to contact and maintain in a predetermined position the external surface of the web 4 of packaging material. In other words, the superior supporting element 18A may be integrated into the forming ring 13A.

[0038] The supporting elements 18 may comprise an intermediate supporting element 18B. Said intermediate supporting element 18B is placed downstream of the folding device 12A along the conveying path P.

[0039] Advantageously, the intermediate supporting element 18B is attached/connected to the first folding device 12A, i.e. to the first folding ring 13A. Alternatively, the intermediate supporting element 18B is advantageously arranged at a distance with respect to the folding device 12A and attached thereto by means of a fixed arm 19. The intermediate supporting element 18B is realized to contact and maintain in a predetermined position the external surface of the web 4 of packaging material; in particular, the intermediate supporting element 18B is realized to contact and maintain in a predetermined position the external surface of the lateral portions 4A.

[0040] According to a possible embodiment, the intermediate supporting element 18B comprises a number of rollers 20 carried by the arm 19. Preferably, the number of rollers 20 is comprised within one and four. The arm 19 projects downwards along the conveying path P towards the folding device 12B. The arm 19 is connected to the structure 11; preferably, the arm 19 is connected to the folding ring 13A. The arm 19 (and, as a consequence, the rollers 20) is arranged in a fixed position with respect to the tube 10; the arm 19 (and, as a consequence, the rollers 20) is arranged in a fixed position with respect to the folding devices 12. The rollers 20 are arranged in succession one after the other, with their axis parallel one to another, in the area of the sealing region.

[0041] Advantageously, the supporting elements 18 are in a fixed position. The movable parts of the forming unit and/or sealing unit relatively move with respect to the supporting elements 18.

[0042] Finally, the tube 10 is continuously filled with the pourable food product through a pour conduit 21, which partially extends inside the tube 10 and is part of a filling circuit. The tube 10 is sent to a transverse forming sealing unit (not shown), in which the tube 10 is gripped to transversely seal the tube and form pillow packs 2. Finally, the pillow packs 2 are subjected to successive mechanical folding operations to obtain the finished sealed packages.

[0043] In all the embodiments described above, the supporting element 18 (either superior, intermediate or inferior) is arranged in a fixed position with respect to the folding devices 12.

[0044] The normal operation of the packaging machine 1 comprises the step of positioning the heating element 16 in the operating position wherein the heating element 16 is interposed between the two lateral portions 4A, 4B and facing the internal surface of the lateral portion 4A at the packaging material. During the normal operation of the packaging machine 1, the heating element 16 is placed in the gap defined between the two lateral portions 4A, 4B so as to direct heat onto the internal surface of the lateral portion 4A in the operating position.

[0045] When the advancement of the web 4 of packaging material along the conveying path P is interrupted, the heating element 16 is moved from the operating position to the rest position wherein the heating element 16 is away from the web 4 of packaging material, thereby avoiding directing too much heat onto the internal surface of the lateral portion 4A. The supporting elements 18 maintain in a fixed and predetermined position the web 4 of packaging material for the time in which the heating element 16 is arranged in the rest position. Finally, when the advancement of the web 4 of packaging material along the conveying path P resumes, the heating element 16 is moved from the rest position to the operating position.

LIST OF REFERENCE NUMBERS

[0046] 

1

packaging machine

2

pillow pack

3

reel

4

web of packaging material

4A,4B

lateral portion

5

sterilizing unit

6

guiding element

7

sterilizing bath

8

guiding element

9

forming unit

10

tube

11

structure

12,12A,12B

folding device

13,13A,13B

forming ring

14,14A,14B

folding roller

15

sealing unit

16

heating element

18,18A,18B

supporting element

19

arm

20

roller

21

pour conduit

P

conveying path

Y

axis

Claims

1. A forming unit (9) for folding a web (4) of packaging material into a tube (10) and superimpose a first lateral portion (4A) of the web (4) of packaging material to a second lateral portion (4B) of the web (4) of packaging material comprising:

- a number of forming devices (12) placed along a conveying path (P) in succession and configured to fold the web (4); and

- a plurality of supporting elements (18) configured to contact and maintain in a predetermined position said first and second lateral portion (4A, 4B) of the web (4) of packaging material; wherein said plurality of supporting elements (18) is arranged in a fixed position with respect to the forming devices (12).

2. A forming unit according to claim 1, wherein the supporting elements (18) comprise rollers or conical shaped elements ("fingers").

3. A forming unit according to claim 1 or 2, wherein at least a supporting element (18) is realized to contact and maintain in a predetermined position an external surface of the first lateral portion (4A) and/or a surface of the second lateral portion (4B) facing the first lateral portion (4A).

4. A forming unit according to anyone of the previous claims, wherein each forming device (12) supports a number of folding rollers (14) cooperating with each other to fold the web (4) of packaging material; and wherein the supporting elements (18) comprise a folding roller (14).

5. A forming unit according to anyone of the previous claims, wherein at least a first supporting element (18) is connected/attached to a first forming device (12).

6. A forming unit according to anyone of the previous claims, wherein at least a second supporting element (18) is arranged at a distance from a second forming device (12); preferably, the second supporting element (18) is arranged on an arm connected to the second forming device (12) .

7. A forming unit according to anyone of the previous claims and comprising a plurality of supporting elements (18) arranged along the conveying path (P) in succession, preferably interposed between two forming devices (12).

8. A forming unit according to anyone of the previous claims wherein each forming device (12) is substantially ring shaped and at least partially encloses the web (4) of packaging material being folded.

9. An apparatus for producing a sealed tube (10) of packaging material comprising a forming unit (9) realized according to anyone of the claim from 1 to 8 and a sealing unit (15) for sealing overlapping first and second lateral portions (4A, 4B) arranged along the conveying path (P) in a sealing region; wherein the sealing unit (15) is preferably interposed between two forming devices (12).

10. An apparatus according to claim 9 wherein the sealing unit (15) comprises a heating element (16) supported by an arm movable between an operating position wherein the heating element (16) is interposed between the first and second lateral portions (4A, 4B) and facing an internal surface of the first lateral portion (4A) and a rest position wherein the heating element (16) is away from the web (4) of packaging material; and vice versa from the rest position to the operating position.

11. An apparatus according to claim 10, wherein the heating element (16) comprises an induction heating element (16) for inductively heating the internal surface of the first lateral portion (4A) and/or a hot air heating element (16) having a number of nozzles for directing hot air onto the internal surface of the first lateral portion (4A).

12. A packaging machine (1) for producing sealed packages from a packaging material fed along the conveying path (P), the packaging (1) machine comprising an apparatus realized according to anyone of claims 9 to 11.

13. A method to operate an apparatus realized according to anyone of claims 9 to 11 and comprising the steps of:

- arranging the sealing unit (15) in an operating position interposed between the first and second lateral portions (4A, 4B) and facing an internal surface of the first lateral portion (4A) so as to direct heat onto the internal surface of the first lateral portion (4A);

- when the advancement of the web (4) of packaging material along the conveying path (P) is interrupted, moving the sealing unit (15) in a rest position away from the web (4) of packaging material, thereby avoiding directing too much heat onto the internal surface of first lateral portion (4A) and maintaining in a fixed and predetermined position the web (4) of packaging material by means of said plurality of supporting elements (18); and

- when the advancement of the web (4) of packaging material along the conveying path (P) resumes, moving the sealing unit (15) back to the operating position.

Drawing