Apparatus for removing liquid from the surface of a paper web

Abstract

An apparatus is provided for efficiently reducing residual hydrogen peroxide or other germicidal substances from the surface of a paper web. The subject of the present invention is an apparatus for removing liquid from the surface of a paper web (20). The apparatus comprises a paper folding tower (30) integrally formed with a paper web (20) to be folded and a substantially vertical bottom wall (40). The paper web (20) and the bottom wall (40) cooperate to define a drying tunnel (50) for the paper web (20). The apparatus comprises an air outlet (60) for supplying sterile air to the drying tunnel (50). The bottom wall (40) of the removal device is provided with a baffle (70) for deflecting the supplied sterile air, and the baffle (70) is configured to define a first length of the drying tunnel (50) having a cross-section that gradually decreases from the position of the air outlet (60) until it reaches a minimum cross-section, and a second length of the drying tunnel (50) having a cross-section that gradually increases from the position of the minimum cross-section of the drying tunnel (50).

Description

[Technical field]

[0001] The subject of the present invention is a device for removing liquid from the surface of a paper web. The invention also includes a packaging machine for containers for liquid products incorporating an improved device for removing liquid from the surface of a paper web. [Background technology]

[0002] As is known, there are machines for packaging containers for liquid products, for example for food use, such as milk, fruit juices, etc.

[0003] In particular, there are packaging machines capable of producing containers in which the two side walls and the bottom wall are sealed, so that the top surface of the container is not sealed and a plug can be provided to open the containers of very large dimensions.

[0004] Known packaging machines of this type generally operate from a reel of paper and are provided with a series of rollers which unwind the paper web from the reel and transport it towards a tank in which it is moistened with a sterilising solution, for example hydrogen peroxide.

[0005] The paper web then passes through hot rollers where the hydrogen peroxide (or other germicidal solution) is first evaporated, and then through a substantially vertical path between a lower guide roller and an upper conical roller, which constitutes a paper folding unit or paper folding tower. In this process the paper web is folded in half. This folding tower is in effect integrally formed by the folded paper web in half and a substantially vertical bottom wall, which together define a drying tunnel for the paper web. The actual drying is performed by air outlets which supply sterile air from top to bottom vertically, i.e. opposite to the paper feed direction, into this drying tunnel in order to evaporate and remove any residues of hydrogen peroxide or other germicidal solution still present on the inner surface of the paper web.

[0006] The folded paper web then passes through a creasing assembly, then through a container filling assembly, which then rolls and seals two adjacent containers, and finally, individual containers are formed from the continuous paper tube and ready for transport.

[0007] US Pat. No. 5,399,633 discloses a method and apparatus for sterilizing web material during processing in packaging and filling machines. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] GB 1246324 Summary of the Invention [Problem to be solved by the invention]

[0009] A substantial problem that remains unsolved in the prior art is the inability to reduce residual hydrogen peroxide or other residual sterilizing substances to the high standards currently enforced by some legislation.

[0010] Therefore, the object of the present invention is to solve the above problems by providing an apparatus for removing liquid from the surface of a paper web, thereby improving the efficiency of reducing residual hydrogen peroxide (or other sterilizing substances) on the paper web before the container is formed.

[0011] A further object of the present invention is to achieve the above mentioned results in a simple and economical manner. [Means for solving the problem]

[0012] The present invention therefore aims to achieve the aforementioned object by means of an apparatus for removing liquid from the surface of a paper web, said apparatus comprising a paper folding tower integrally formed by a paper web to be folded and a substantially vertical bottom wall, said paper web and said bottom wall cooperating to define a drying tunnel for said paper web, said apparatus comprising an air outlet for supplying sterile air to said drying tunnel, said bottom wall comprising a baffle for deflecting the supplied sterile air, said baffle being adapted to define a first length of said drying tunnel having a cross-section which gradually decreases from the position of said air outlet until it reaches a minimum cross-section, and a second length of said drying tunnel having a cross-section which gradually increases from the position of said minimum cross-section of said drying tunnel.

[0013] An advantage of the present invention is that it converts a paper folding tower into an improved drying tunnel that essentially functions as a Venturi tube.

[0014] Indeed, the invention achieves an increase in the sterile air flow velocity with a corresponding reduction in the cross section of the drying tunnel.

[0015] The use of baffles reduces the available volume of the drying tunnel, so for the same airflow rate, the air is renewed more frequently per unit time, improving the drying process.

[0016] Additionally, an increase in the vorticity of the flow is achieved, improving the performance of the removal device.

[0017] Thus, the present invention can improve efficiency by ensuring that residual hydrogen peroxide (or other residual sterilizing agent) is reduced to less than 0.01 ppm.

[0018] The invention also includes a packaging machine for containers for liquid products, comprising a device for removing liquid from the surface of a paper web, said device being arranged between at least one tank in which the paper web is moistened with a sterilizing solution and an assembly for creasing, filling, sealing and forming said containers, in particular of a type suitable for producing containers having sealing lines on two sides and on the bottom, the top side remaining unsealed (usually provided with a plug for opening the container).

[0019] Further features of the invention can be derived from the dependent claims.

[0020] Further features and advantages of the present invention will become more apparent in light of the following detailed description, taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is an axonometric view of a drying tunnel according to one embodiment of the present invention. [Diagram 2] FIG. 2 is an exploded view of the drying tunnel of FIG. [Diagram 3] FIG. 2 is a cross-sectional view of the drying tunnel of FIG. [Figure 4] 1 is a graph showing the rate of increase in sterile air flow velocity as a function of the reduction in cross-section of the drying tunnel. [Diagram 5] 1 is a graph showing a comparison of sterile air flow velocity between a removal device according to the prior art and a removal device according to an embodiment of the present invention. [Figure 6] FIG. 1 is a schematic axonometric view of the flow of a paper web in a packaging machine according to the prior art; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The invention will be described first with reference to Figure 1, in which a drying tunnel 50 according to one embodiment of the invention is depicted in an axonometric view.

[0023] The drying tunnel 50 is part of an apparatus for removing liquid from the surface of the paper web 20 according to one embodiment of the present invention.

[0024] In particular, the liquid to be removed from the surface of the paper web 20 is hydrogen peroxide or other sterilizing liquid or substance.

[0025] The removal device, which is arranged in a packaging machine for containers for pourable products, comprises a paper folding tower 30, which is integrally formed by the paper web 20 to be folded and a substantially vertical bottom wall 40. In this process, the paper web 20 is folded in half so that at the end of the folding and sealing process of the paper web 20, the final container leaving the packaging machine has sealing lines only on two sides and on the bottom, and therefore the top is not sealed.

[0026] FIG. 6 shows the flow of the paper web in a packaging machine 200 of the known art. Starting from a reel 101, it reaches a sterilization tank 102 containing hydrogen peroxide (or other sterilization solution) located just before a hot roller 103, then passes through said hot roller 103 and subsequently through a folding tower 104, which is equipped with air outlets (not shown) inside that supply air to the drying tunnel in a vertical direction from top to bottom, i.e. opposite to the paper feed direction. The folded paper web then passes through a container creasing assembly 105, then through a container filling assembly 106, and then is sealed, properly folded and prepared for transport. The final containers 107 then have sealing lines on two sides and on the lower or bottom side where they are usually placed, but not on the top side where the spouts are usually placed.

[0027] According to the embodiment of the invention described herein, the paper web 20 and the bottom wall 40 cooperate to define a drying tunnel 50 for the paper web 20 .

[0028] The removal apparatus also includes an air outlet 60 which supplies sterile air to the drying tunnel 50 .

[0029] In addition, the bottom wall 40 is provided with a baffle 70 for deflecting the supplied sterile air, which defines a first length of the drying tunnel 50 having a cross-section that gradually decreases from the position of the aforementioned air outlet 60 until a minimum cross-section is reached, and a second length of the drying tunnel 50 having a cross-section that gradually increases from the position of the minimum cross-section of the drying tunnel 50.

[0030] In this manner, the drying tunnel 50 essentially operates as a Venturi tube, as will be better explained below.

[0031] In particular, as can be seen in the exploded view of the drying tunnel in FIG. 2, the baffle 70 has a polyhedral shape, with at least one face 80 of the polyhedron being inclined relative to the vertical direction of the bottom wall 40, and having a portion near the air outlet 60 that protrudes toward the inside of the drying tunnel 50.

[0032] Moreover, a face 80 of the polyhedron that is inclined with respect to the vertical direction of the bottom wall 40 is shaped like an isosceles triangle.

[0033] The isosceles triangle has an apex 90 opposite its base 90 ′ and is positioned proximal to the air outlet 60 .

[0034] As shown in both Figures 2 and 3, air outlets 60 are adapted to supply sterile air vertically downward into drying tunnel 50, ie, opposite the paper feed direction.

[0035] The removal apparatus of the present invention further includes a paper guide assembly 100 that holds the paper web 20 stably attached to the lower portion of the bottom wall 40 so that the velocity, vorticity, and overpressure parameters of the sterile air supplied to the drying tunnel 50 are approximately constant over time within the same drying tunnel 50.

[0036] In particular, the paper guide assembly 100 includes a pair of slide blocks (110) that slide to hold the paper web 20 coupled to the lower portion of the bottom wall 40.

[0037] Additionally, the paper guide assembly 100 includes at least one roller 120 that secures the paper web 20 to the lower portion of the bottom wall 40 .

[0038] Preferably, the paper guide assembly 100 is located outside the drying tunnel 50 and includes a plurality of idler rollers 130 mounted on an arch 140 that guides the paper web 20 .

[0039] FIG. 4 is a graph showing the rate of increase in sterile air flow velocity as the cross-section of drying tunnel 50 decreases.

[0040] Theoretical trends of velocity and pressure according to a mathematical model were used to generate the graph in Figure 4.

[0041] The present invention can potentially increase the flow rate within the drying tunnel 50 by approximately 100%.

[0042] FIG. 5 is a graph showing a comparison of the sterile air flow velocity in a known art removal device, i.e., a folding tunnel without baffles 70 (curve A), with the sterile air flow velocity in a removal device according to one embodiment of the present invention (curve B).

[0043] Again, theoretical trends derived from mathematical models are used.

[0044] The pressure drop due to the Venturi effect is offset by the local pressure drop caused by the baffle 70. This increases the back pressure in the drying tunnel (measured experimentally at the cross section), which further reduces the risk of non-sterile air ingressing from the sides of the drying tower. The paper guide assembly 100 is used to ensure that as the air pressure in the drying tunnel increases, the flow does not try to escape from the sides, but instead traverses the entire tunnel and exits from the bottom.

[0045] The present invention further includes a pourable product container packaging machine incorporating an apparatus for removing liquid from the surface of a paper web 20 as described above.

[0046] In particular, in this packaging machine, the device for removing liquid from the surface of the paper web 20 is arranged between at least one tank in which this paper web is moistened with a disinfecting solution and an assembly for creasing, filling, sealing and forming the containers. In particular, this packaging machine is of a type suitable for producing containers having sealing lines on two sides and on the bottom, the top side remaining unsealed (usually provided with a plug for opening the container).

[0047] Obviously, modifications or improvements which are necessary for certain reasons, whether accidental or not, may be made in the practice of the present invention without departing from the scope of the following claims. [Explanation of symbols]

[0048] 20 Paper Web 30 Paper Folding Tower 40 Bottom Wall 50 Drying Tunnel 60 Air outlet 70 Baffle 80 Polyhedral Faces 90 Vertex 90' Bottom 100 Paper guide assembly 101 Reels 102 Sterilization tank 103 Hot Roller 104 Folding Tower 105 Creasing Assembly 106 Filling Assembly 107 Final container 110 Slide Block 120 Roller 130 Idler roller 140 Arch 200 Packaging machine of the prior art

Claims

1. A removal device for removing liquid from a surface of a paper web (20), the removal device comprising a paper folding tower (30), the paper folding tower (30) being integrally formed by the paper web (20) to be folded and a vertical bottom wall (40), the paper web (20) and the bottom wall (40) cooperating to define a drying tunnel (50) for the paper web (20), the removal device comprising an air outlet (60) for supplying sterile air to the drying tunnel (50), a wall (40) provided with a baffle (70) for deflecting the supplied sterile air, the baffle (70) being adapted to define a first length of the drying tunnel (50) having a cross-section that gradually decreases from the position of the air outlet (60) until it reaches a minimum cross-section, and a second length of the drying tunnel (50) having a cross-section that gradually increases from the position of the minimum cross-section of the drying tunnel (50).

2. The baffle (70) has a polyhedral shape, at least one face (80) of the polyhedral surface is inclined with respect to the vertical direction of the bottom wall (40), and has a portion protruding toward the inside of the drying tunnel (50) near the air outlet (60).

3. 3. The device for removing liquid from the surface of a paper web (20) according to claim 2, characterized in that the face (80) of the polyhedron inclined relative to the vertical direction of the bottom wall (40) has the shape of an isosceles triangle and has an apex (90) opposite the base (90') of the isosceles triangle and located in a position proximal to the air outlet (60).

4. 2. The apparatus for removing liquid from the surface of a paper web (20) according to claim 1, characterized in that the air outlet (60) supplies the sterile air into the drying tunnel (50) in a vertical, downward direction opposite to the paper feed direction.

5. 2. The device for removing liquid from the surface of a paper web (20) as described in claim 1, further comprising a paper guide assembly (100) for holding the paper web (20) firmly attached to the lower part of the bottom wall (40) so that the parameters of velocity, vorticity and overpressure of the sterile air supplied to the drying tunnel (50) are constant over time within the same drying tunnel (50).

6. The removal device for removing liquid from the surface of a paper web (20) as described in claim 5, characterized in that the paper guide assembly (100) includes a pair of slide blocks (110) for holding the paper web (20) which is connected to the lower part of the bottom wall (40) by sliding.

7. The apparatus for removing liquid from the surface of a paper web (20) according to claim 5, characterized in that the paper guide assembly (100) comprises at least one roller (120) that secures the paper web (20) to the lower portion of the bottom wall (40).

8. The apparatus for removing liquid from the surface of a paper web (20) as described in claim 5, characterized in that the paper guide assembly (100) is located outside the drying tunnel (50) and comprises a plurality of idler rollers (130) mounted on an arch (140) that guides the paper web (20).

9. A packaging machine for containers for liquid products, characterized in that it comprises a removal device for removing fluids from the surface of a paper web (20) according to any one of claims 1 to 8.

10. 10. The packaging machine for liquid product containers according to claim 9, characterized in that the removal device for removing liquid from the surface of the paper web (20) is arranged between at least one tank in which the paper web (20) is moistened with a sterilizing solution and an assembly for creasing, filling, sealing and forming the liquid product containers.

11. 11. A packaging machine for containers for liquid products according to claim 9 or 10, characterized in that the packaging machine is adapted to produce containers having sealing lines on two sides and on the bottom, the top side of the container remaining unsealed.

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