Packaging machine and method for producing sealed packages

Abstract

A packaging machine (1) is described that includes a conveying device (5) for advancing a web (4) along a web advancement path (P) to at least a tube forming station (6) where the web (4) is formed into a tube (3), and for advancing a tube (3) along a tube advancement path (Q), a tube forming and sealing device (10) configured to form and longitudinally seal the tube (3), a tensioning device (32) disposed upstream of the tube forming station (6) and configured to control the tension in the tube (3), and a control unit (13) configured to control operation of the packaging machine (1). The tensioning device (32) includes a primary drive roller (33) rotatable about a primary axis of rotation (A), and a primary drive motor (34) configured to actuate rotation of the primary drive roller (33) about the primary axis of rotation (A). The control unit (13) is configured to control the main drive motor (34) such that the angular velocity and / or angular acceleration of the main drive roller (33) is periodically varied to thus control the tension in the tube (3).

Description

[Technical field]

[0001] The present invention relates to a packaging machine for producing sealed packages of pourable products, particularly pourable food products.

[0002] The present invention also relates to a method for producing a sealed package of a pourable product, in particular a pourable food product. [Background technology]

[0003] 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 from sterilized packaging materials.

[0004] A typical example is the parallelepiped-shaped package for liquid or pourable food products known as Tetra Brik Aseptic®, which is made by sealing and folding laminated strip packaging material. The packaging material has a multi-layer structure including a base layer, e.g. paper, covered on both sides with a layer of heat-sealed plastic material, e.g. polyethylene. In the case of aseptic packages for long-storage products such as UHT milk, the packaging material also includes a layer of oxygen barrier material (oxygen barrier layer), e.g. aluminum foil, which is superimposed on the layer of heat-sealed plastic material and then covered with another layer of heat-sealed plastic material that finally forms the inner surface of the package that contacts the food product.

[0005] This type of package is typically produced on a fully automatic packaging machine which advances a web of packaging material through a sterilizer to an isolation chamber (closed sterile environment) for sterilizing the web of packaging material at a sterilization station, and the sterilized web of packaging material is maintained and advanced within the isolation chamber. During the advancement of the web of packaging material through the isolation chamber, the web of packaging material is folded and longitudinally sealed at a tube forming station to form a tube having a longitudinal seam, and the tube is fed further along the vertical advance direction.

[0006] To complete the forming operation, the tube is filled with a sterilized or pasteurized pourable product, in particular a pourable food product, transversely sealed and then cut along equally spaced transverse cross sections within a package forming unit of the packaging machine as it advances along a vertical advance direction.

[0007] Pillow packages are thus obtained in the packaging machine, each pillow package having a longitudinal seal strip, a top lateral seal strip and a bottom lateral seal strip.

[0008] A typical packaging machine includes a conveying device for advancing a web of packaging material along a web advancement path and a tube formed from the web of packaging material along a tube advancement path, a sterilization apparatus for sterilizing the web of packaging material before it is formed into a tube, a tube forming and sealing device disposed at least partially within the isolation chamber and configured to form a tube from the advancing web of packaging material and seal the tube longitudinally, a filling device for filling the tube with a pourable product, and a package forming unit adapted to form, transversely seal and cut single packages from the tube of packaging material.

[0009] A typical packaging machine also includes a tensioning device configured to control the tension in the tube.

[0010] Specifically, it is known to place a tensioning device between the sterilization station and the tube forming station to control the tension in the tube.

[0011] A typical tensioning device includes at least one first roller rotatable about a first axis of rotation, one first counter roller adjacent to the first roller, one second roller rotatable about a second axis of rotation and disposed downstream of the first roller, one second counter roller adjacent to the second roller, and a drive motor associated with the second roller for actuating rotation of the second roller about the second axis of rotation.

[0012] A typical tensioning device further includes a pendulum roller sandwiched between the first roller and the second roller and configured to tension a portion of the web of packaging material expanding between the first roller and the second roller.

[0013] It should be noted that operation of the package forming unit is cyclical resulting in a cyclical force which changes the forward speed of the tube.

[0014] The tensioning device is therefore controlled such that the drive motor controls a constant rotational speed of the second roller which corresponds to the average forward speed of the tube, and the actuation of the pendulum roller compensates for the difference between the forward speed of the web resulting from the rotation of the second roller and the forward speed of the tube.

[0015] Applicants have discovered that while control of tube tension can be sufficiently good to allow reliable production of packages, the tube tension does vary in part in an uncontrolled manner.

[0016] It is therefore felt that it would be desirable to improve known tensioning devices and methods of producing packages so as to improve the accuracy and / or reliability of tension control. Summary of the Invention [Problem to be solved by the invention]

[0017] It is therefore an object of the present invention to provide a packaging machine to overcome in a simple manner at least one of the above mentioned drawbacks.

[0018] Specifically, it is an object of the present invention to provide a packaging machine with improved tension control.

[0019] In order to overcome in a simple manner at least one of the aforementioned drawbacks, it is a further object of the present invention to provide a method for producing a sealed package.

[0020] In particular, it is an object of the present invention to provide a method with improved tension control. [Means for solving the problem]

[0021] According to the present invention there is provided a packaging machine and a method for producing a sealed package as claimed in the respective independent claims.

[0022] Preferred embodiments are claimed in the dependent claims.

[0023] Non-limiting embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0024] [Figure 1] 1 is a schematic diagram, with parts removed for clarity, of a packaging machine according to the present invention; FIG. [Diagram 2] FIG. 2 is a schematic diagram of a portion of the packaging machine of FIG. 1 with parts removed for clarity. [Diagram 3] FIG. 2 is a perspective view of a detail of the packaging machine of FIG. 1 with parts removed for clarity. [Figure 4] FIG. 4 is an enlarged perspective view of some of the details of FIG. 3 with parts removed for clarity; [Diagram 5] FIG. 4 is a perspective view of a detail of FIG. 3 from a different perspective, with parts removed for clarity; [Figure 6] 2 shows the time-dependent periodic velocity profile of an advancing tube during operation of the packaging machine of FIG. 1. [Figure 7] 1 shows the time-dependent velocity profile of an advancing tube during the formation of a single package from the tube. [Figure 8] 2 illustrates, with parts removed for clarity, a control scheme for controlling at least one drive motor present in the packaging machine of FIG. 1; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Number 1 generally indicates a packaging machine for producing sealed packages 2 of pourable product, in particular pourable food products such as pasteurized milk, fruit juice, wine, tomato sauce, etc., from a tube 3 of a web 4 of packaging material. In particular, in use, the tube 3 extends along a longitudinal axis which preferably has a vertical orientation.

[0026] The web 4 has a multi-layer structure (not shown) and includes at least one layer of fibrous material, such as a paper or paperboard layer, and at least two layers of heat-sealable plastic material, such as polyethylene, sandwiching the layer of fibrous material between each other, one of these two layers of heat-sealable plastic material defining the inner surface of the package 2 that will ultimately contact the pourable product.

[0027] Preferably, but not necessarily, the web 4 also includes a layer of gas and light blocking material, such as aluminum foil or ethylene vinyl alcohol (EVOH) film, specifically disposed between one of the layers of heat-sealable plastic material and the layer of fibrous material. Preferably, but not necessarily, the web 4 also includes a further layer of heat-sealable plastic material sandwiched between the layer of gas and light blocking material and the layer of fibrous material.

[0028] According to a preferred, non-limiting embodiment, web 4 includes a first side and a second side, specifically the first side is the side of web 4 that forms the inner surface of the formed package 2 that will ultimately contact the filled pourable food product.

[0029] According to a preferred, non-limiting embodiment, a typical package 2 obtained by the packaging machine 1 includes a longitudinal seam and a pair of lateral sealing strips, specifically a lateral top sealing strip and a lateral bottom sealing strip.

[0030] With specific reference to FIG. 1 , packaging machine 1 is configured to advance web 4 along a web advancement path P, preferably sterilize web 4 while advancing along path P, to form and longitudinally seal a tube 3 from web 4, preferably fill tube 3 with a pourable product, and preferably form a single package 2 from the filled tube 3.

[0031] With particular reference to Figures 1 and 2, the packaging machine 1 includes: a conveying device 5 configured to advance the web 4 along a web advancement path P to at least a tube forming station 6 where the web 4 is, in use, formed into a tube 3, for advancing the tube 3 along a tube advancement path Q; an isolation chamber 7 having an internal (sterile) environment 8 and extending along a longitudinal axis, preferably but not necessarily having a vertical orientation; a tube forming and sealing device 9 disposed at least partially within the isolated chamber 7 and configured to form and longitudinally seal the tube 3 at the tube forming station 6, specifically within at least a portion of the isolated chamber 7, and even more specifically within the internal environment 8; In particular a filling device 10 for filling the tube 3 with a pourable product; and a package forming unit 11 adapted (configured) to at least form and laterally seal the tube 3, and preferably also to laterally cut the tube 3, between successive packages 2, in particular while advancing the tube 3 along the tube advancement path Q, in order to form the package 2 itself.

[0032] According to a preferred, non-limiting embodiment, the packaging machine 1 further includes a sterilization device for sterilizing at least a portion of the web 4, preferably at least a first side, and even more preferably the first and second sides, in particular at a sterilization station located upstream of the tube forming station 6 along the web advancement path P.

[0033] According to a preferred, non-limiting embodiment, the packaging machine 1 also includes a control unit 13 for controlling the operation of the packaging machine 1 itself.

[0034] According to a preferred, non-limiting embodiment, the packaging machine 1 also includes a magazine unit adapted to host and present the web 4 at the host station. In particular, the conveying device 5 is configured to advance the web 4 from the host station to the tube forming station 6.

[0035] In particular, the package forming unit 11 is disposed along path Q downstream of the isolated chamber 7 and the tube forming and sealing device 9 .

[0036] Preferably, but not necessarily, the conveying device 5 is adapted to advance the tube 3 and any intermediate part of the tube 3 in a known manner, such as along a path Q, in particular from the tube forming station 6 through the isolation chamber 7, in particular towards and at least partially through the package forming unit 11. Any configuration of the web 4, in particular with an intermediate part of the tube 3, is meant before obtaining a tube structure as well as after the tube forming and sealing device 9 has started folding the web 4. In other words, the intermediate part of the tube 3 is the result of a gradual folding of the web 4 to obtain the tube 3, in particular by overlapping the opposing lateral edges of the web 4 on one another.

[0037] According to a preferred, non-limiting embodiment, the sterilization device is configured to sterilize the web 4, particularly the first side, and even more particularly the second side, by physical sterilization, such as sterilizing radiation, particularly electromagnetic radiation, and even more particularly electron beam irradiation.

[0038] Alternatively or additionally, the sterilization device may be configured to sterilize the web 4, particularly the first side and even more particularly the second side, by chemical sterilization, particularly by hydrogen peroxide.

[0039] According to a preferred, non-limiting embodiment, the isolation chamber 7 separates an internal environment 8 from an external environment, and specifically allows the tube 3 to be formed and filled within a controlled environment. Specifically, the internal environment 8 contains a sterile gas.

[0040] 1 and 2, the filling device 10 includes at least a filling pipe 19 in fluid communication with a storage tank of pourable product (not shown, but known as such) and extending partially into the isolated chamber 7, specifically the internal environment 8. Specifically, in use, the filling pipe 19 is located partially within the tube 3 for delivering the pourable product into the tube 3 which advances in use.

[0041] With specific reference to FIG. 1 , the tube forming and sealing device 9 includes at least a tube forming assembly 20 configured to form a tube 3 from a web 4, specifically by overlapping respective lateral edges of the web 4, and at least a sealing head 21 configured to seal the tube 3 longitudinally, specifically along a portion of the tube 3 obtained by overlapping the lateral edges of the web 4.

[0042] Preferably, but not necessarily, the tube forming assembly 20 and sealing head 21 are disposed within the isolated chamber 7 , specifically within the interior environment 8 .

[0043] Preferably, but not necessarily, the tube forming assembly 20 includes at least a plurality, in the illustrated embodiment two, of forming ring assemblies 22 adapted to gradually fold the web 4 into the tube 3. Specifically, the forming ring assemblies 22 are arranged in parallel spaced apart planes, specifically perpendicular to the longitudinal axis of the isolation chamber 7, and even more specifically have a substantially horizontal orientation.

[0044] Preferably, but not necessarily, the tube forming and sealing device 9 also includes a pressure assembly configured to apply a mechanical force to the tube 3, particularly to improve longitudinal sealing of the tube 3. Specifically, the pressure assembly is associated with a forming ring assembly 22 that is disposed downstream of the other forming ring assembly 22 along the web advancement path P and / or the tube advancement path Q.

[0045] According to a preferred, non-limiting embodiment, the package forming unit 11 includes a plurality of pairs of at least one respective actuating assembly 23 (only one shown) and at least one counter actuating assembly 24 (only one shown); Specifically, it includes at least one transport unit (not shown and known as such) adapted to advance a pair of respective actuating assemblies 23 and respective counter actuating assemblies 24 along a respective transport path.

[0046] Preferably, but not necessarily, each actuating assembly 23 is adapted to cooperate in use with a respective counter actuating assembly 24 of a respective pair to form a respective package 2 from the tube 3. In particular, each actuating assembly 23 and each counter actuating assembly 24 is configured to shape, transversely seal and preferably, but not necessarily, also transversely cut the tube 3 to form a package 2 as it advances along a respective actuating portion of a respective conveying path in use.

[0047] Preferably, but not necessarily, each actuating assembly 23 and each counter actuating assembly 24 are adapted to cooperate with each other to form a respective package 2 from the tube 3 as it advances along its respective actuating portion of the respective conveying path.

[0048] Preferably, but not necessarily, each actuating assembly 23 and each counter actuating assembly 24 is configured to contact tube 3 as it advances along its respective actuating portion of its respective transport path, specifically when it begins to contact tube 3 at a (fixed) hit position.

[0049] Preferably, but not necessarily, each actuation assembly 23 and counter actuation assembly 24 comprises: a half shell 25 adapted to contact the tube 3 and to at least partially define the shape of the package 2; one of a sealing element 26 and a counterseal element 27 adapted to laterally seal the tube 3 between adjacent packages 2 in a known manner; Preferably, but not necessarily, it includes one of a cutting element (not shown, but known as such) and an anti-cutting element (not shown, but known as such) for cutting the tube 3 transversely between adjacent packages 2 in a manner known as such.

[0050] Preferably, but not necessarily, each half-shell 25 is adapted to be controlled by means of a drive assembly (not shown) between a working position and a rest position, in particular each half-shell 25 is adapted to be controlled in the working position by a respective actuating assembly 23 or a respective counter-actuating assembly 24 which, in use, advances along a respective actuating section.

[0051] Preferably, but not necessarily, each sealing element 26 and each counterseal element 27 is adapted to be controlled between an actuated sealing position in which the sealing element 26 and each counterseal element 27 are adapted to contact and laterally seal with the tube 3, and a rest position in which the sealing element 26 and each counterseal element 27 are separated from the tube 3. In particular, each sealing element 26 and each counterseal element 27 is adapted to be controlled in the sealing position by the respective actuating assembly 23 or the respective counter actuating assembly 24 which, in use, advances along the respective actuating portion.

[0052] Preferably, but not necessarily, each half-shell 25 is configured to be controlled in a respective working position, with the respective sealing element 26 and counter-seal element 27 being controlled in the respective working position.

[0053] Preferably, but not necessarily, each actuating assembly 23 and each counter-actuating assembly 24 is configured to apply a traction force to the tube 3 in order to cooperate with the transport unit to advance the tube 3 along the tube advancement path Q. Since the functions of the actuating assembly 23 and the counter-actuating assembly 24 proceed with varying steps, the traction force is not linear but exhibits a complex behavior resulting in a complex profile of the advancement speed of the tube 3, as shown by way of example in Figures 6 and 7.

[0054] Preferably, but not necessarily, the actuation assembly 23 , the counter actuation assembly 24 and the transport unit can be considered to form part of the transport device 5 .

[0055] It should be noted that the forces acting on the tube 3 and resulting from the interaction with the actuating assembly 23 and the counter-actuating assembly 24 depend on the various steps of forming the package 2 (package formation cycle). The forces acting on the tube 3 vary, for example, due to the sealing element 26 and the counter-seal element 27 contacting the tube 3 when they are controlled in their respective actuating positions and / or when the half-shells 25 are controlled in their respective working positions, and / or due to the traction of the tube 3 caused by the advancement of the actuating assembly 23 and the counter-actuating assembly 24 along their respective conveying paths.

[0056] Specifically, the interaction of the actuating assembly 23 and the counter-actuating assembly 24 with the tube 3 also results in a periodic advancement velocity of the web 4 (specifically, the portion of the web 4 advancing downstream of the tensioning device 32 along the web advancement path P) and / or the tube 3, as shown in Figures 6 and 7.

[0057] Specifically, during the process of forming the package 2 (using the package forming unit 11), there is a complex cyclical behavior of the acting forces (similar to the cyclic advancement speeds shown in Figures 6 and 7).

[0058] With specific reference to Figures 1 and 2, the packaging machine 1 also includes at least one tensioning device 32 configured to control the tension of at least the tube 3, in particular depending on the cyclic advance speed of the web 4 and / or the tube 3 and / or depending on the operation of the package forming unit 11.

[0059] Specifically, the tensioning device 32 is positioned upstream of the tube forming station 6 along the web advancement path P and is configured to control the tension of the tube 3 and specifically the portion of the web 4 extending between the tensioning device 32 and the tube forming and sealing device 9 and / or the tube forming station 6.

[0060] Even more specifically, the tensioning device 32 is positioned upstream of the tube forming station 6 and / or the tube forming and sealing device 9 and downstream of the sterilization station and / or the sterilization device.

[0061] Conveniently, the control unit 13 is configured to control the operation of the tensioning device 32 .

[0062] With specific reference to FIGS. 1-5, the tensioning device 32 includes at least a primary first drive roller 33 rotatable about a primary axis of rotation A; a main drive motor 33, specifically a servo motor, coupled to the main drive roller 34 and configured to actuate rotation of the main drive roller 33 about the axis of rotation A.

[0063] According to a preferred, non-limiting embodiment, tensioning device 32 comprises: An auxiliary drive roller 35 rotatable around an auxiliary rotation axis B; It further includes an auxiliary drive motor (not shown), specifically an auxiliary servo motor, coupled to the auxiliary drive roller 35 and configured to actuate and / or control the rotation of the auxiliary drive roller 35 about the rotation axis B.

[0064] It should be noted that Figures 3 and 5 show a first portion of the tensioning device 32, having the main drive rollers 33 and the main drive motors 34. A second portion of each tensioning device 32, having the auxiliary drive rollers 35 and the respective auxiliary drive motors, is not explicitly shown, as the second portion is substantially identical to the first portion.

[0065] According to a preferred, non-limiting embodiment, the auxiliary drive roller 35 and the main drive roller 33 of each tensioning device 32 are spaced apart along the web advancement path P, specifically, the auxiliary drive roller 35 is positioned upstream of the main drive roller 33.

[0066] According to a preferred, non-limiting embodiment, the tensioning device 32 comprises at least a main counter roller 36 rotatable about a central axis C and arranged adjacent to, and more specifically circumferentially adjacent to, and more specifically tangential to, the main drive roller 33; In particular, it further includes an auxiliary counter roller 37 rotatable about the central axis E and arranged adjacent to the auxiliary drive roller 35, specifically adjacent to it in the circumferential direction, and even more specifically in contact with it.

[0067] According to a preferred, non-limiting embodiment, and in accordance with the arrangement of the auxiliary drive roller 35 and the main drive roller 33, the auxiliary counter roller 37 is disposed along the web advancement path P upstream of the main counter roller 36.

[0068] Specifically, in use the web 4 is pinched and / or advanced between the respective primary counter rollers 36 and primary drive rollers 33, and between the auxiliary counter rollers 37 and auxiliary drive rollers 35. In other words, during the advancement of the web 4 in use the web 4 advances between the primary drive rollers 33 and primary counter rollers 36, and between the auxiliary drive rollers 35 and auxiliary counter rollers 37.

[0069] Advantageously, the control unit 13 is configured to control the main drive motor 34 such that the angular velocity of the main drive roller 33 is periodically varied to control the tension in the tube 3, and specifically also the tension in the portion of the web 4 extending between the main drive roller 33 and the tube forming station 6.

[0070] Specifically in the context of this specification, the term "periodically modified" indicates that the angular velocity and / or angular acceleration of the main drive roller 33 follows a time-dependent velocity profile and / or a time-dependent acceleration profile, respectively, that repeats according to a defined and / or determined and / or given frequency.

[0071] In other words, the control unit 13 is configured to control the main drive motor 34 such that the angular velocity and / or angular acceleration of the main drive roller 33 are periodically changed according to respective time-dependent velocity and / or acceleration profiles that repeat according to a defined operating frequency.

[0072] It should be noted, however, that according to some non-limiting embodiments, the particular velocity profile and / or acceleration profile that is repeated may be modified during operation of the packaging machine 1, particularly according to a feedback loop.

[0073] Even more specifically, the time-dependent speed profile is defined according to the periodicity of the production of the packages 2 and / or the operation of the package forming unit 11 .

[0074] In particular, it is advantageous to control the angular velocity and / or angular acceleration of the main drive rollers 33 about their respective axes of rotation A (and respective main drive motors 34) according to respective periodic velocity and / or acceleration profiles as the forces acting on the tube 3 during the formation of the package 2 cycle.

[0075] According to a preferred, non-limiting embodiment, the control unit 13 is configured to control the main drive motor 34 such that the angular velocity and / or angular acceleration of the main drive roller 33 are varied and / or controlled as a function of the operation of the package forming unit 11 and / or as a function of the package forming cycle and / or the force acting on the tube 3 and / or the operation of the filling device 10 and filling the tube 3.

[0076] Specifically, the package formation cycle is substantially determined by the interaction of the actuating assembly 22 and the counter-actuating assembly 23, specifically the respective half shells 25, sealing element 26 and counter-seal element 27 with the tube 3.

[0077] In particular, as described above, the forces acting on the tube 3 result from the interaction of the actuating assembly 23 and the counter-actuating assembly 24 with the tube 3, and the various steps of forming the package 2 are controlled, in particular due to the respective sealing elements 26 and counter-seal elements 27, at their respective sealing positions, and / or the respective half shells 25 in their working positions, and / or the actuating assembly 23 and the counter-actuating assembly 24 advancing along their respective working parts of the conveying path, and / or the pourable product being introduced into the tube 3 through the filling pipe 19.

[0078] It should be noted that the actuation of the package forming unit 11 (and the interaction of the actuating assembly 23 and the counter-actuating assembly 24 with the tube 3) determines the cyclic advancement speed of the web 4 (specifically the portion of the web 4 downstream of the tensioning device 32) and / or the tube 3 as shown in Figure 6. In particular, the cyclic advancement speed profile of Figure 6 is the repetition (according to a defined frequency) of the advancement speed of the web 4 and / or the tube 3 during the formation of one single package 2 as shown in Figure 7.

[0079] More specifically, the advancement speed shown in Figure 7 is determined by the manipulation of the tube 3 by means of the respective actuating assembly 23 and counter-actuating assembly 24. As the package forming unit 11 continuously forms packages 2, the advancement speed of Figure 7 also continuously repeats according to a defined frequency (although variations and / or deviations may occur).

[0080] According to a preferred, non-limiting embodiment, the control unit 13 is configured to control the main drive motor 34 such that the angular velocity and / or angular acceleration of the main drive roller 33 is changed according to at least one predefined and / or predetermined periodic velocity profile and / or acceleration profile, i.e. the velocity profile and / or acceleration profile repeats in particular according to a predefined and / or predetermined frequency, even more particularly substantially according to the production cycle of the package 2.

[0081] In particular, such speed profile and / or such acceleration profile and / or speed profiles and / or acceleration profiles are determined and / or defined as a function of the type and / or format of the package 2, and / or the advancement speed of the web 4 and / or the tube 3, and / or the advancement speed of the actuation assembly 23 and the counter actuation assembly 24, and / or the type of pourable product. Even more particularly, the respective speed profile and / or the respective acceleration profile is determined and / or measured at a factory setting (i.e. it is determined and / or measured before operation of the packaging machine 1 and / or the package forming unit 11 and / or the filling device 11 and is coded in the respective speed profile of the main drive roller 33).

[0082] It should be noted that the system including the tensioning device 32 and the part of the web 4 and / or tube 3 downstream of the tension can be represented by the following formula: Jdω / dt=Cm+T*r, where J is the moment of inertia of the group including at least the main drive motor 34 and the main drive roller 33, ω=(v(t)) / r, v(t) is the time-dependent forward velocity of the web 4 and / or tube 3 downstream of the tensioning device 32 along the forward movement path P as determined by the package forming unit 11, r is the radius of the main drive roller 33, Cm is the motor torque, and T is the tension in the web 4 and / or tube 3 downstream of the tensioning device 32 along the forward movement path P.

[0083] As mentioned above, the advancement speed of the web 4 and / or the tube 3 is not a controllable variable by the tensioning device 32 since it depends on the operation of the package forming unit 11, and therefore it is possible to control the tension of the web 4 and / or the tube 3 by controlling the motor torque Cm of the main drive motor 34, or in other words the angular velocity and / or angular acceleration transferred by the main drive motor 34 to the main drive roller 33. The motor torque can be expressed as Cm=Jdω / dt-T*r. In the particular case where the tension T should be kept (substantially) constant, the motor torque Cm is proportional to the rotational torque Jdω / dt.

[0084] Preferably, but not necessarily, the control unit 13 stores one or more speed and / or acceleration profiles which can be selected in use for control of the tensioning devices 32, and in particular at least each of the main drive motors 34.

[0085] It should be noted that in accordance with the present invention, the acceleration profile and / or angular acceleration 143 includes positive and negative acceleration (deceleration).

[0086] 8, the control unit 13 includes a portion 39 configured to control the operation of the main drive motor 34. In particular, the portion 39 includes one or more PID controllers 40 (proportional integral derivative controllers), each configured to receive a respective control variable, such as the angular position or angular acceleration or angular velocity of the main drive roller 33.

[0087] According to a preferred, non-limiting embodiment, portion 39 receives information about the angular position of the main drive roller 33, specifically the set angular position obtained from the velocity profile, and by performing first and second derivatives, the angular position is converted into an acceleration variable which is fed into the respective PID controller 40. Preferably, but not necessarily, only the PID controller 40 receiving the angular acceleration information is active, while the others are inactive (if expected).

[0088] Additionally or alternatively, the angular velocity and / or angular acceleration are fed into portion 39 for control of the main drive motor 34 .

[0089] According to a preferred, non-limiting embodiment, the control unit 13 is also configured to control the auxiliary drive motor and the main drive motor 34 so that the free loop 38 of the web 4 expands and / or advances between the auxiliary drive roller 35 and the main drive roller 33 in use.

[0090] In the context of the present invention, the term free loop 38 indicates that the portion of web 4 expanding and / or advancing between auxiliary drive roller 35 and main drive roller 33 is not under any tension and defines and / or forms free loop 38, i.e., the portion of web 4 defining and / or forming free loop 38 is not exposed to tension and / or is free of any tension. In other words, free loop 38 is a portion of web 4 that is not under tension.

[0091] Preferably, but not necessarily, the control unit 13 is configured to control the auxiliary drive motor such that the angular velocity of the auxiliary drive roller 35 maintains and / or controls, in particular the expansion of, the free loop 38 expanding and / or advancing between the auxiliary drive roller 35 and the main drive roller 33.

[0092] In particular, in use, the angular velocity of the auxiliary drive rollers 35 substantially controls the expansion of each free loop 38 , whilst the angular velocity of the main drive rollers 33 substantially controls the tension in the tube 3 .

[0093] Preferably, but not necessarily, the control unit 13 is configured to control the auxiliary drive motor such that the angular velocity of the auxiliary drive roller 35 is substantially constant. In particular, substantially constant means that the possible changes in the angular velocity of the auxiliary drive roller 35 occur at a lower rate than the changes in the angular velocity of the main drive roller 33.

[0094] According to a preferred, non-limiting embodiment, the control unit 13 is configured to operate and / or control the main drive motor 34 and / or the angular velocity of the main drive roller 33, to control the auxiliary drive motor and, accordingly, the auxiliary drive roller 35.

[0095] According to a preferred, non-limiting embodiment, each tensioning device 32 also includes at least one sensor element 41 configured to determine and / or measure the extension and / or level of each free loop 38 during use (i.e., the longitudinal length of the portion of the web 4 that expands and / or extends between each auxiliary drive roller 35 and each main drive roller 33).

[0096] Preferably, but not necessarily, each sensor element 41 is configured to determine and / or measure the position of an apex 42 of each free loop 38 as an indication of the extension and / or level of each free loop 38 .

[0097] According to a preferred, non-limiting embodiment, the tensioning device 32 further includes an actuation group 46 configured to (locally) control the orientation and / or advancement direction of the web 4, in particular to modify and / or control the relative orientation between the respective central axis E and the respective rotation axis B, and / or to modify and / or control the relative orientation between the respective central axis C and the respective rotation axis A.

[0098] Preferably, but not necessarily, the actuation group 46 is coupled and / or connected to the respective auxiliary counter roller 37 and / or main counter roller 36 and configured to control and / or vary the orientation of the respective corresponding central axis E and the respective corresponding central axis C relative to the respective corresponding axis of rotation B and the respective corresponding axis of rotation A in order to locally control the advancement direction and / or orientation and / or alignment of the web 4. In particular, locally controlled means that the advancement direction and / or orientation and / or alignment of the web 4 is controlled immediately downstream of the tensioning device 32 along the advancement path P.

[0099] 3-5, tensioning device 32 includes a support structure 47 that carries and / or supports auxiliary drive roller 35 and auxiliary drive motor, main drive roller 33 and main drive motor 34.

[0100] Preferably, but not necessarily, the support structure 47 also carries and / or supports the auxiliary counter rollers 36 or the main counter rollers 36 and / or the working group 46 .

[0101] According to a preferred, non-limiting embodiment, the support structure 47 comprises at least one support bar 48 which (at least indirectly) carries either the auxiliary counter roller 37 or the main counter roller 36 and which extends along the central axis F, in particular parallel to each of the relative rotation axes B and A. Preferably, but not necessarily, the support structure 47 comprises two support bars 48, one which carries the auxiliary counter roller 37 and the other which carries the main counter roller 36.

[0102] Preferably, but not necessarily, each support bar 48 is rotatable about a respective central axis F.

[0103] It should be noted that Figures 3 and 5 show the first part of the tensioning device 32, i.e. the support bar 48 shown carries (at least indirectly) the main counter roller 36. The structure of the second part of the tensioning device 32 is similar to that of the first part, so in the following only the first part is described. The difference between the first and second parts is that the second part includes the auxiliary drive roller 35 and the auxiliary counter roller 37.

[0104] In particular, the support structure 47 pivots on a support bar 48 about a pivot axis G and includes at least one coupling element 49 which is connected to and directly carries the respective auxiliary counter roller 37 or the main counter roller 36 .

[0105] According to a preferred, non-limiting embodiment, the actuation group 46 is configured to control the angular position of the coupling element 49 about the respective pivot axis G to control the relative position of the central axis C with respect to the primary rotation axis A, or the central axis E with respect to the secondary rotation axis B.

[0106] Preferably, but not necessarily, each actuation group 46 includes at least a control bar 50 rotatable about a respective axis of rotation I, in particular parallel to a respective central axis F, and configured to interact with a respective coupling element 49; and an electric motor 51 configured to control the angular position of a control bar 50 about a rotation axis I for controlling the angular position of the coupling element 49 about the pivot axis G.

[0107] Specifically, in use, modifying the angular position of control bar 50 about its respective axis of rotation I causes coupling element 49 to pivot about pivot axis G, which in turn modifies the orientation of central axis C or central axis E.

[0108] Preferably, but not necessarily, each control bar 50 includes an interaction portion 52, particularly in the form of a cam, configured to interact with an interaction member 53 of the respective coupling element 49, particularly defining a cam follower, to couple the angular position of the respective control bar 50 to the angular position of the respective coupling element 49.

[0109] According to a preferred, non-limiting embodiment, each tensioning device 32 also includes at least one actuating assembly 56 configured to control the angular position of at least one respective support bar 48 about a respective central axis F to move the main counter roller 36 closer to or away from the main drive roller 33 or the auxiliary drive roller 35, or to move the auxiliary counter roller 37 closer to or away from the auxiliary drive roller 35, or away from the main drive roller 33.

[0110] According to the non-limiting embodiment shown, each actuation assembly 56 includes a linear actuator 57 and at least one bar element 58 coupled to the linear actuator 57 and to a respective support bar 48 .

[0111] Preferably, but not necessarily, each bar element 58 is perpendicular to the respective support bar 48 and the piston 59 of the respective linear actuator 57 .

[0112] According to an alternative embodiment not shown, each actuation assembly 57 can include at least one motor, e.g., a stepper motor, coupled to a respective support bar 48 and configured to control the angular position of the respective support bar 48.

[0113] In use, the packaging machine 1 forms a package 2 filled with a pourable product.

[0114] More specifically, the main production cycle includes at least the following steps: advancing the web 4 along an advancing path P; folding the web 4 into a tube 3 in a tube forming station 6, specifically in an isolated chamber 7; - advancing the tube 3 along a tube advancement path Q, in particular towards and at least partially through the package forming unit 11; and controlling the tension of the tube 3 using the tensioning device 32.

[0115] Preferably, but not necessarily, the method comprises the following steps: Sealing the tube 3 longitudinally, in particular in the isolation chamber 7, and / or Filling the tube 3 with a pourable product, and / or forming single packages 2 from the tube 3 by forming the tube 3, sealing the tube 3 transversely between successive packages 2, and in particular cutting the tube 3 transversely between successive packages 2, in order to obtain single packages 2 while advancing the tube 3 along the tube advancement path Q; and / or sterilizing the web 4 in a sterilization station 8, and / or It also includes controlling and / or modifying the orientation of web 4, during which web 4 is specifically selectively locally oriented and / or aligned.

[0116] According to a preferred, non-limiting embodiment, during the step of advancing the web 4 , the transport device 5 advances the web 4 along a web advancement path P.

[0117] According to a preferred, non-limiting embodiment, during the step of folding the tube 3, the tube forming and sealing device 9 gradually overlaps the opposing lateral edges of the web 4 onto one another to form a longitudinal seam.

[0118] According to a preferred, non-limiting embodiment, during the step of longitudinally sealing the tube 3, the tube forming and sealing device 9 seals the longitudinal seam by directing heat onto the longitudinal seam.

[0119] According to a preferred, non-limiting embodiment, during the step of advancing the tube 3, the conveying device 5 advances the tube 3 (and any intermediate bodies of the tube 3), in particular through the isolated chamber 7 along path Q into and partially through the package forming unit 11.

[0120] According to a preferred, non-limiting embodiment, during the step of filling the tube 3, the filling device 10 fills the injectable product into the longitudinally sealed tube 3. In particular, the injectable product is directed into the tube 3 through a filling pipe 19.

[0121] According to a preferred, non-limiting embodiment, during the step of sterilizing the web 4, at least the first side, in particular the second side, of the web 4 is also sterilized.

[0122] Preferably, but not necessarily, during the step of sterilizing web 4, sterilizing radiation, particularly electromagnetic radiation, even more particularly electron beam radiation, is directed onto at least a first surface of web 4, and preferably also onto a second surface.

[0123] According to a preferred, non-limiting embodiment, the sterilizing step is performed before the folding step.

[0124] According to a preferred, non-limiting embodiment, during the step of forming a single package 2, the package forming unit 11 forms and transversely seals a tube 3 between consecutive packages 2, and preferably also cuts the tube 3 transversely between consecutive packages 2.

[0125] Preferably, but not necessarily, during the step of forming the single packages 2, the actuating assembly 23 and the counter-actuating assembly 24 advance along their respective conveying paths and cyclically form and transversely seal, and in particular also transversely cut, the tube 3 to obtain the packages 2. In particular, the sealing element 26 and the counter-seal element 27 move from their respective rest positions to their respective sealing positions to transversely seal the tube 3 between successive packages 2, and the half-shells 25 move from their respective rest positions to their respective working positions to form the tube 3.

[0126] According to a preferred, non-limiting embodiment, during the step of controlling the tension, the tensioning device 32 controls the tension of at least the tube 3 .

[0127] According to a preferred, non-limiting embodiment, during the tension controlling step, the main drive roller 33 rotates about the main axis of rotation A, and the angular velocity and / or angular acceleration of the main drive roller 33 is periodically changed. Specifically, the main drive motor 34 actuates the rotation of the main drive roller 33, and even more specifically controls the periodic change in the angular velocity and / or angular acceleration of the main drive roller 33.

[0128] According to a preferred, non-limiting embodiment, during the tension controlling step, the angular velocity of the main drive roller 33 is periodically varied as a function of the package forming unit 11, and / or the filling device 10, and / or the type and / or format of the package 2, and / or the package forming cycle.

[0129] Preferably, but not necessarily, the angular velocity and / or angular acceleration of the main drive roller 33 is varied according to a predefined and / or predetermined velocity and acceleration profile, respectively.

[0130] According to a preferred, non-limiting embodiment, during the tension control step, the auxiliary drive roller 35 rotates about the auxiliary axis of rotation B and the main drive roller 33 rotates about the main axis of rotation A such that the free loop 38 expands and / or advances between the auxiliary drive roller 35 and the main drive roller 33.

[0131] Preferably, but not necessarily, during the step of controlling tension, the control unit 13 selectively and independently controls the respective auxiliary drive motors 34 and main drive motors 34 to control the rotation of the respective auxiliary drive rollers 35 and main drive rollers 33.

[0132] According to a preferred, non-limiting embodiment, during the tension control step, the angular velocity of the auxiliary drive roller 35 should maintain a free loop 38 of the auxiliary drive roller 35 and the main drive roller 33 .

[0133] Preferably, but not necessarily, the angular velocity of the auxiliary drive roller 35 is substantially constant.

[0134] According to a preferred, non-limiting embodiment, the step of controlling and / or modifying includes the sub-steps of controlling and / or modifying the relative orientation between at least the central axis E and the rotation axis B, and / or the relative orientation between at least the central axis C and the rotation axis A.

[0135] Preferably, but not necessarily, during the controlling and / or correcting sub-step, the orientation of at least the central axis C is controlled and / or corrected relative to the respective rotational axis A in order to control the advancement direction and / or orientation of the web 4, specifically using the actuation group 46.

[0136] Preferably, but not necessarily, during the controlling and / or correcting sub-step, the angular position of the respective control bar 50 is controlled and / or corrected by a respective electric motor 51 in order to pivot the respective coupling element 49 about the respective pivot axis G in order to control and / or correct the orientation of the respective primary counter roller 36 or auxiliary counter roller 37.

[0137] According to a preferred, non-limiting embodiment, the controlling and / or modifying step includes the sub-step of modifying the relative distance between the respective main counter rollers 36 and the main drive rollers 33, or between the auxiliary counter rollers 37 and the auxiliary drive rollers 35, by actuation of the respective actuation assemblies 56.

[0138] The advantages of the packaging machine 1 according to the invention will become apparent from the above description.

[0139] In particular, the tensioning device 32 improves and provides more precise control of tension in the tube 3. This is achieved by the tensioning device 32 having a main drive roller 33 that is driven according to a cyclic speed profile. Advantageously, this cyclic speed profile is synchronised to the cyclic advance speed of the tube 3 as determined by the operation of the package forming unit 11.

[0140] A further advantage consists in controlling the main drive roller 33 according to a predefined speed profile. In this way, the main drive roller 33 can be controlled by the cyclic forces acting on the tube 3 during operation of the package forming unit 11.

[0141] A further advantage is in providing an auxiliary drive roller 35 and driving the auxiliary drive roller 35 so that the untensioned portion of the web 4, i.e. the free loop 38, advances between the auxiliary drive roller 35 and the main drive roller 33 in use.

[0142] A still further advantage is that by controlling the relative orientation between at least one auxiliary drive roller 35 and the respective auxiliary counter roller 37, and / or at least one main drive roller 33 and the main counter roller 36, the alignment and / or orientation and / or advance direction of the web 4 can be controlled.

[0143] Obviously, modifications may be made to the packaging machine 1 and method as described herein, but without departing from the scope of protection as defined in the appended claims.

Claims

1. A packaging machine (1) for producing sealed packages (2) of pourable products from a web (4) of packaging material, comprising: a conveying device (5) for advancing said web of packaging material (4) along a web advancement path (P) to at least a tube forming station (6) where said web of packaging material (4) is formed, in use, into a tube (3), and for advancing said tube (3) along a tube advancement path (Q); a tube forming and sealing device (10) configured to form the tube (3) at the tube forming station (6) and to longitudinally seal the tube (3); a tensioning device (32) arranged upstream of the tube forming station (6) along the web advancement path (P) and configured to control the tension of at least the tube (3); a control unit (13) configured to control the operation of said packaging machine (1); Including, The tensioning device (32) comprises at least a main drive roller (33) rotatable about a main axis of rotation (A); a main drive motor (34) coupled to said main drive roller (33) and configured to actuate rotation of said main drive roller (33) about said main axis of rotation (A); a package forming unit (11) adapted in use to at least form and transversely seal said tube (3) during advancement of said tube (3) along said tube advancement path (Q); Including, The package forming unit (11) continuously forms the package (2), the control unit (13) is configured to control the main drive motor (34) such that the angular velocity and / or the angular acceleration of the main drive roller (33) is periodically changed, the advancement speed of said web (4) being continuously repeated according to a defined frequency; the control unit (13) is configured to control the main drive motor (34) such that the angular velocity and / or angular acceleration of the main drive roller (33) is varied and / or controlled as a function of the operation of the package forming unit (11). Packaging machine (1).

2. the control unit (13) is configured to control the main drive motor (34) such that the angular velocity and / or the angular acceleration of the main drive roller (33) is varied and / or controlled as a function of the period of forming the package and / or as a function of the advancement speed of the web of packaging material (4) and / or of the tube (3), 2. The packaging machine of claim 1.

3. 3. The packaging machine according to claim 1 or 2, wherein the control unit (13) is configured to control the main drive motor (34) such that the angular velocity and / or the angular acceleration of the main drive roller (33) is varied according to a predefined and / or predetermined velocity profile and / or acceleration profile, respectively.

4. The tensioning device (32) also includes a main counter roller (36), The main counter roller (36) is disposed adjacent to the main drive roller (33); In use, the web of packaging material (4) is pinched and / or advanced between the main counter roller (36) and the main drive roller (33); 4. The packaging machine according to claim 1, wherein the tensioning device (32) comprises an actuation group (46) configured to control and / or modify the relative orientation between a central axis (C) of the main counter roller (36) and the main rotation axis (A) of the main drive roller (33).

5. an auxiliary drive roller (35) rotatable about an auxiliary rotation axis (B); an auxiliary drive motor configured to actuate rotation of the auxiliary drive roller (35) about the auxiliary rotation axis (B); 5. A packaging machine as claimed in any one of claims 1 to 4, wherein the control unit (13) is arranged to control the auxiliary drive motor and the main drive motor (34) such that, in use, a free loop (38) of the web of packaging material (4) expands and / or advances between the auxiliary drive roller (35) and the main drive roller (33).

6. 6. The packaging machine of claim 5, wherein the auxiliary drive roller (35) is positioned upstream of the main drive roller (33) along the web advancement path (P).

7. 7. A packaging machine as claimed in claim 5 or 6, wherein the control unit (13) is arranged to control the auxiliary drive motor (30) such that the angular velocity of the auxiliary drive roller (35) maintains the free loop (38) in use.

8. The packaging machine according to any one of claims 5 to 7, wherein the control unit (13) is configured to control the auxiliary drive motor (34) such that the angular velocity of the auxiliary drive roller (35) is substantially constant.

9. a sterilization device configured to sterilize the web of packaging material (4) at a sterilization station upstream of the tube forming station (6) along the web advancement path (P); A packaging machine according to any one of the preceding claims, wherein the tensioning device (32) is sandwiched between the sterilisation station and the tube forming station (6).

10. 1. A method for producing a sealed package (2) of a pourable product from a web (4) of packaging material, comprising the steps of: At least the following steps: advancing said web of packaging material (4) along a web advancement path (P) to at least a tube forming station (6); forming said web of packaging material (4) into a tube (3) at said tube forming station (6); advancing the tube (3) along a tube advancement path (Q); controlling the tension of the tube (3) by a tensioning device (32); forming a unitary package (2) from said tube (3) by at least forming and transversely sealing said tube (3) while advancing said tube (3) along said tube advancement path (Q); Including, A package forming unit (11) continuously forms the package (2), said tensioning device (32) being arranged along said web advancement path (P) upstream of said tube forming station (6) and having at least a main drive roller (33) rotatable about a main axis of rotation (A); During the tension control step, the main drive roller (33) rotates about the main axis of rotation (A), the angular velocity and / or the angular acceleration of the main drive roller (33) is periodically varied and the advancement speed of the web (4) is continuously repeated according to a defined frequency, During the step of controlling the tension, the angular velocity and / or the angular acceleration are varied as a function of the step of forming a single package (2). method.

11. 11. The method according to claim 10, wherein during the step of controlling the tension, the angular velocity and / or the angular acceleration are varied as a function of the advancement speed of the web of packaging material (4) along the web advancement path (P) and / or the advancement speed of the tube (3) along the tube advancement path (Q).

12. 12. The method according to claim 10 or 11, wherein the angular velocity and / or the angular acceleration of the main drive roller (33) is varied according to a predefined and / or predetermined velocity profile and / or acceleration profile, respectively.

13. The tensioning device (32) also includes a main counter roller (36) disposed adjacent to the periphery of the main drive roller (33); During the step of advancing the web of packaging material (4), the web of packaging material (4) advances between the main counter roller (36) and the main drive roller (33), The method according to any one of claims 10 to 12, further comprising the step of controlling and / or modifying the relative orientation between a central axis (C) of the main counter roller (36) and the main rotation axis (A) of the main drive roller (33).

14. the tensioning device (32) further comprises an auxiliary drive roller (35) rotatable about an auxiliary axis of rotation (B) and arranged upstream of the main drive roller (33) along the web advancement path (P); 14. The method according to any one of claims 10 to 13, wherein during the tension controlling step, the auxiliary drive roller (35) rotates about the auxiliary axis of rotation (B) and the main drive roller (33) rotates about the main axis of rotation (A) such that a free loop (38) of the web of packaging material (4) expands and / or advances between the auxiliary drive roller (35) and the main drive roller (33).

15. 15. The method of claim 14, wherein during the step of controlling tension, the angular velocity of the auxiliary drive roller (35) maintains a free loop (38) of the web of packaging material (4).

16. 16. The method of claim 15, wherein the angular velocity of the auxiliary drive roller (35) is substantially constant.

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