Patent Publication Number: US-11383869-B2

Title: Packaging machine and method for producing sealed packages

Description:
TECHNICAL FIELD 
     The present invention relates to a packaging machine for producing sealed packages of a pourable product, in particular a pourable food product. 
     The present invention also relates to a method for producing sealed packages of a pourable product, in particular a pourable food product. 
     BACKGROUND ART 
     As is known, many liquid or pourable food products, such as fruit juice, UHT (ultra-high-temperature treated) milk, wine, tomato sauce, etc., are sold in packages made of sterilized packaging material. 
     A typical example is the parallelepiped-shaped package for liquid or pourable food products known as Tetra Brik Aseptic (registered trademark), which is made by sealing and folding laminated strip packaging material. The packaging material has a multilayer structure comprising a base layer, e.g. of paper, covered on both sides with layers of heat-seal plastic material, e.g. polyethylene. In the case of aseptic packages for long-storage products, such as UHT milk, the packaging material also comprises a layer of oxygen-barrier material (an oxygen-barrier layer), e.g. an aluminum foil, which is superimposed on a layer of heat-seal plastic material, and is in turn covered with another layer of heat-seal plastic material forming the inner face of the package eventually contacting the food product. 
     Packages of this sort are normally produced on fully automatic packaging machines, which advance a web of packaging material from a magazine unit through a sterilization apparatus for sterilizing the web of packaging material and to an isolation chamber (a closed and sterile environment) in which the sterilized web of packaging material is maintained and advanced. During advancement of the web of packaging material through the isolation chamber, the web of packaging material is folded and sealed longitudinally to form a tube having a longitudinal seam portion, which is further fed along a vertical advancing direction. 
     In order to complete the forming operations, the tube is filled with a sterilized or sterile-processed pourable product, in particular a pourable food product, and is transversally sealed and subsequently cut along equally spaced transversal cross sections within a package forming unit of the packaging machine during advancement along the vertical advancing direction. 
     Pillow packages are so obtained within the packaging machine, each pillow package having a longitudinal sealing band, a top transversal sealing band and a bottom transversal sealing band. 
     In the recent years, sterilization apparatuses have become available, which are configured to sterilize the web of packaging material by means of the application of physical irradiation, in particular electromagnetic irradiation, even more particular electron beam irradiation. 
     A typical sterilization apparatus of this kind comprises an irradiation device typically having a pair of electron beam emitters spaced apart from one another. An advancement channel, through which, in use, the web of packaging material advances, is interposed between the electron beam emitters. Each one of the electron beam emitters is adapted to direct the respective electron beam onto one respective face of the web of packaging material advancing through the advancement channel. 
     Furthermore, such a kind of sterilization apparatus must provide for means that guarantee to safely discharge ozone and other undesired components, which may form during the application of the sterilizing irradiation. 
     For this reason, a typical sterilization apparatus sterilizing by means of a sterilizing irradiation comprises a main shielding chamber housing the irradiation device, a first auxiliary shielding chamber connected to the main shielding chamber and arranged upstream of the main shielding chamber and a second auxiliary shielding chamber connected to the main shielding chamber and being arranged downstream of the main shielding chamber. In use, the un-sterilized web of packaging material enters the first auxiliary shielding chamber, is sterilized within the main shielding chamber and the sterilized web of packaging material enters the second auxiliary shielding chamber from where it advances into the isolation chamber. 
     Furthermore, the sterilization apparatus also comprises an isolation housing, which houses in its inner space the main shielding chamber, the first auxiliary shielding chamber and the second auxiliary shielding chamber and from which any undesired components are extracted. 
     A drawback of this design is that a complex control mechanism must be applied so as to guarantee the sterility within the aseptic environments within the packaging machine. 
     Even though this kind of sterilization apparatus and, accordingly, also the packaging machine provides for good results, a desire is felt to simplify the design of these packaging machines, in particular for simplifying the control of the aseptic environments of the packaging machine. 
     DISCLOSURE OF INVENTION 
     It is therefore an object of the present invention to provide a packaging machine to overcome, in a straightforward and low-cost manner, at least one of the aforementioned drawbacks. 
     In particular, it is an object of the present invention to provide a packaging machine, which comes along with a simplified design. 
     It is a further object of the present invention to provide a method for producing sealed packages to overcome, in a straightforward and low-cost manner, at least one of the aforementioned drawbacks. 
     According to the present invention, there is provided a packaging machine according to claim  1 . 
     According to the present invention, there is also provided a method for producing sealed packages according to claim  9 . 
     Preferred embodiments are claimed in the dependent claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which: 
         FIG. 1  is a schematic view of a packaging machine having a sterilization apparatus according to the present invention, with parts removed for clarity; and 
         FIG. 2  is a sectionized view of the sterilization apparatus of  FIG. 1 , with parts removed for clarity; 
         FIG. 3  is a partially sectionized and perspective view of a detail of the sterilization apparatus of  FIG. 2 ; and 
         FIG. 4  is a partially sectionized and perspective view of another detail of the sterilization apparatus of  FIG. 2 . 
     
    
    
     BEST MODES FOR CARRYING OUT THE INVENTION 
     Number  1  indicates as a whole a packaging machine for producing sealed packages  2  of a pourable product, in particular a pourable food product 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, tube  3  extends along a longitudinal axis, in particular having a vertical orientation. 
     Web  4  at least comprises a layer of fibrous material, in particular paper, covered on both sides with respective layers of heat-seal plastic material, e.g. polyethylene. 
     Preferably, web  4  also comprises a layer of gas- and light-barrier material, e.g. aluminum foil or ethylene vinyl alcohol (EVOH) film, and at least a first layer and a second layer of heat-seal plastic material. The layer of gas- and light-barrier material is superimposed on the first layer of heat-seal plastic material, and is in turn covered with the second layer of heat-seal plastic material. The second layer of heat-seal plastic material forms the inner face of package  2  eventually contacting the filled pourable food product. 
     More specifically, web  4  comprises a first face  5  and a second face  6 , in particular first face  5  being the face of web  4  forming the inner face of the formed package  2  eventually contacting the filled pourable food product. 
     A typical package  2  obtained by packaging machine  1  comprises a longitudinal seam portion and a pair of transversal sealing bands, in particular a transversal top sealing band and a transversal bottom sealing band. 
     With particular reference to  FIG. 1 , packaging machine  1  is configured to advance web  4  along a web advancement path P, to sterilize web  4  during advancement along path P, to form tube  3  from web  4  and to fill tube  3  and to form single packages  2  from the filled tube  3 . 
     Preferentially, packaging machine  1  comprises:
         a magazine unit  7  adapted to provide for web  4  at a host station  8 ;   a sterilization apparatus  9  configured to sterilize at least first face  5 , preferentially also second face  6 , of web  4  at a sterilization station  10 , arranged downstream of host station  8  along path P;   an isolation chamber  14  connected to sterilization apparatus  9  and separating an inner environment  15 , in particular an inner sterile environment, from an outer environment  16  and being configured to receive the sterilized web  4  from sterilization apparatus  9 ;   a tube forming device  17  extending along a longitudinal axis, in particular having a vertical orientation, and being arranged, in particular at a tube forming station  18 , at least partially, preferably fully, within isolation chamber  14  and being adapted to form tube  3  from the, in use, advancing and sterilized web  4 ;   a sealing device  19  at least partially arranged within isolation chamber  14  and being adapted to longitudinally seal tube  3  formed by tube forming device  17  so as to form a longitudinal seam portion of tube  3 ;   filling means  20  for filling tube  3  with the pourable product, in particular the pourable food product;   a package forming unit  21  adapted to at least form and transversally seal tube  3 , in particular the, in use, advancing tube  3 , for forming packages  2 ; and   conveying means  22  for advancing in a known manner web  4  along path P from host station  8  to tube forming station  18  and to advance tube  3  along a tube advancement path Q towards and at least partially through package forming unit  21 .       

     Preferentially, packaging machine  1  also comprises pressure control means configured to control the pressure within at least isolation chamber  14  and within at least portions of sterilization apparatus  9 . 
     In particular, sterilization station  10  is arranged upstream of tube forming station  17 . In other words, sterilization apparatus  9  is arranged upstream of isolation chamber  14  along path P. 
     Preferentially, sterilization apparatus  9  is arranged downstream of magazine unit  7  along path P. 
     In particular, package forming unit  21  is arranged downstream of isolation chamber  14  and tube forming device  17  along path Q. 
     Preferentially, conveying means  22  are adapted to advance tube  3  and any intermediate of tube  3  in a manner known as such along path Q, in particular from tube forming station  18  towards and at least partially through package forming unit  21 . In particular, with intermediates of tube  3  any configuration of web  4  is meant prior to obtaining the tube structure and after folding of web  4  by tube forming device  16  has started. In other words, the intermediates of tube  3  are a result of the gradual folding of web  4  so as to obtain tube  3 , in particular by overlapping opposite lateral edges of web  4  with one another. 
     With particular reference to  FIG. 1 , sterilization apparatus  9  comprises:
         an irradiation device  26  arranged in the area of sterilization station  10  and being adapted to sterilize at least first face  5 , preferentially also second face  6 , by directing a sterilizing irradiation, in particular electromagnetic irradiation, even more particular electron beam irradiation, onto at least first face  5 , preferentially also onto second face  6 , while, in use, web  4  advances along a sterilization portion P 1  of path P;   a main shielding chamber  27  housing the irradiation device and comprising an advancement channel  28 , in particular extending along a longitudinal axis, having an inlet opening  29  and an outlet opening  30  arranged downstream of inlet opening  29  along path P, and through which, in use, web  4  advances along sterilization portion P 1 ;   a first auxiliary shielding chamber  31  being arranged upstream of advancement channel  28  along path P and having a respective first inner space  32  being in fluid connection with advancement channel  28 .       

     Preferentially, sterilization apparatus  9  also comprises a second auxiliary shielding chamber  33  being arranged downstream of advancement channel  28  along path P and having a second inner space  34  being fluidically connected to advancement channel  28  and inner environment  15 . 
     In particular, advancement channel  28  is interposed between the first inner space  32  and the second inner space  34 . 
     Preferentially, each one of inlet opening  29  and outlet opening  30  extends along a respective extension axis, the respective extension axes being parallel to one another. 
     It should be noted that main shielding chamber  27 , in particular also first auxiliary shielding chamber  31 , even more particular also second auxiliary shielding chamber  33  are configured to shield the sterilizing irradiation, in particular the electromagnetic irradiation, even more particular the electron beam irradiation. The shielding allows to avoid that any sterilizing irradiation, in particular electromagnetic irradiation, even more particular electron beam irradiation, penetrates out of sterilization apparatus  9 . 
     With particular reference to  FIGS. 1 and 2 , irradiation device  26  comprises:
         at least a first irradiation emitter, in particular a first electron beam emitter  35 , configured to direct the sterilizing irradiation, in particular the electromagnetic irradiation, even more particular the electron beam irradiation, in use, on first face  5 ; and   preferentially also a second irradiation emitter, in particular a second electron beam emitter  36 , configured to direct the sterilizing irradiation, in particular the electromagnetic irradiation, even more particular the electron beam irradiation, in use, on second face  6 .       

     Preferably, first electron beam emitter  35  and second electron beam emitter  36  are arranged side-by-side and distanced from one another so that at least a portion of advancement channel  28  is interposed between first electron beam emitter  35  and second electron beam emitter  36 . 
     In particular, first electron beam emitter  35  is placed such to face, in use, first face  5  and second electron beam emitter  36  is placed such to face, in use, second face  6 . 
     In even further detail, first electron beam emitter  35  is arranged within a first portion  37  of main shielding chamber  27  and second electron beam emitter  36  is arranged within a second portion  38  of main shielding chamber  27 . Preferentially, the advancement channel  28  is interposed between the first portion  37  and the second portion  38 . 
     With particular reference to  FIG. 2 , main shielding chamber  27  comprises two inner walls  42  at least partially delimiting advancement channel  28 . In particular, inner walls  42  are parallel to one another and distanced from one another so that the space between inner walls  42  defines advancement channel  28 . 
     Preferentially, one inner wall  42  delimits first portion  37  and the other inner wall  42  delimits second portion  38 . 
     More specifically, each inner wall  42  comprises a respective exit window  43  configured to allow the transmission of electron beam irradiation. In particular, in use, first electron beam emitter  35  and second electron beam emitter  36  transmit the electron beam irradiation onto respective first face  5  and second face  6  through the respective exit window  43 . 
     In further detail, main shielding chamber  27  comprises a first principal wall  44  comprising inlet opening  29  and a second principal wall  45  comprising outlet opening  30 , first principal wall  44  and second principal wall  45  being parallel to and distanced from one another. Main shielding chamber  27  is arranged such that, in use, second principal wall  45  is arranged downstream of second principal wall  44  along path P. 
     Preferentially, inner walls  42  are transversally, in particular perpendicularly, mounted to and are interposed between first principal wall  44  and second principal wall  45 . 
     Preferably, main shielding chamber  27  also comprises outer lateral walls  46  being parallel to inner walls  42  and being interposed between and connected to first principal wall  44  and second principal wall  45 . 
     With particular reference to  FIGS. 2 and 3 , first auxiliary shielding chamber  31  comprises an access opening  47  and a discharge opening  48  for web  4 , in particular through which, in use, web  4  respectively enters into and exits from first auxiliary shielding chamber  31 . 
     Preferentially, access opening  47  and inlet opening  29  are non-coaxially arranged with respect to one another. In other words, access opening  47  is arranged with respect to inlet opening  29  such that an imaginary line extending from access opening  47  to inlet opening  29  is inclined with respect to an imaginary line extending from inlet opening  29  to outlet opening  30  of advancement channel  28 . In even other words, a projection of inlet opening  29  and a projection of access opening  47  onto a projection surface are transversally displaced from one another. In this way, a shielding effect of the sterilizing irradiation is guaranteed in the prolongation of advancement channel  28 . 
     Preferentially, first auxiliary shielding chamber  31  is connected to, in particular mounted to, main shielding chamber  27 . In particular, first auxiliary shielding chamber  31  is positioned such that, in use, first auxiliary shielding chamber  31  is arranged upstream of main shielding chamber  27  along path P. 
     In more detail, first auxiliary shielding chamber  31  comprises a principal plate  49 , in particular parallel to first principal wall  44  and second principal wall  45 , and outer lateral plates  50  connected to, in particular mounted to, principal plate  49  and laterally delimiting first auxiliary shielding chamber  31 . In particular, lateral plates  50  are transversally, in particular perpendicularly, mounted to main shielding chamber  27 , in particular to first principal wall  44 . 
     Preferentially, principal plate  49  comprises access opening  47 . Even more preferentially, principal plate  49  also carries a sealing member  51  for sealing access opening  47  for allowing feeding in of web  4  and limiting entrance of gas into first inner space  32  through access opening  47 . 
     In the preferred embodiment shown, first auxiliary shielding chamber  31 , in particular first inner space  32 , is further delimited by first principal wall  44 . 
     In an alternative embodiment not shown, first auxiliary shielding chamber  31  could comprise a further principal plate parallel to and distanced from principal plate  49  and comprising discharge opening  48 . In such an alternative embodiment, outer lateral plates  50  would be also mounted to the further principal plate and the latter would be mounted to first principal wall  44 . 
     In a preferred embodiment, first auxiliary shielding chamber  31  also comprises an extraction opening  52 , in particular distinct from the access opening  47 , configured to allow to extract gas from first inner space  32  of first auxiliary shielding chamber  31 . 
     In particular, extraction opening  52  is arranged in one of outer lateral plates  50 . 
     In the preferred embodiment shown, sterilization apparatus  9  also comprises a first deviation device, in particular a plurality of rollers  53 , arranged within first auxiliary shielding chamber  31  and configured to direct, in use, web  4  along a deviation portion P 2  of path P from access opening  47  to inlet opening  29 . In particular, in the preferred embodiment, this is necessary as access opening  47  and inlet opening  29  are non-coaxially arranged. 
     With particular reference to  FIGS. 2 and 4 , second auxiliary shielding chamber  33  comprises an access mouth  55  and a discharge mouth  56  for web  4 , in particular through which, in use, web  4  respectively enters into and exits from second auxiliary shielding chamber  33 . 
     Preferentially, sterilization apparatus  9  and isolation chamber  14  are connected to one another through second auxiliary shielding chamber  33 . In other words, in use, web  4  advances through discharge mouth  56  into isolation chamber  14 . 
     Preferentially, second auxiliary shielding chamber  33  comprises a principal plate  57 , in particular distanced from and parallel to first principal wall  44  and second principal wall  45 , and outer lateral plates  58  connected to, in particular transversally mounted to, principal plate  57  and laterally delimiting second auxiliary shielding chamber  33 . In particular, lateral plates  58  are mounted to main shielding chamber  27 , in particular second principal wall  45 . 
     In particular, the lateral plate  58  that delimits isolation chamber  14  comprises discharge mouth  56 . 
     In the preferred embodiment shown, second auxiliary shielding chamber  33  is further delimited by second principal wall  45 . 
     In an alternative embodiment not shown, second auxiliary shielding chamber  33  could comprise a further principal plate parallel to and distanced from principal plate  57  and comprising access mouth  55 . In such an alternative embodiment, outer lateral plates  58  would be also mounted to the further principal plate and the latter would be mounted to second principal wall  45 . 
     In the preferred embodiment shown, sterilization apparatus  9  also comprises a second deviation device, in particular at least one roller  59 , arranged within second auxiliary shielding chamber  33  and configured to direct, in use, web  4  along a deviation portion P 3  of path P from outlet opening  30  to discharge mouth  56 . 
     In a preferred embodiment, sterilization apparatus  9  comprises an aspiration device configured to generate at least:
         a first flow of gas within advancement channel  28  from outlet opening  30  to inlet opening  29  (i.e. the first flow of gas is opposite to the advancement direction of web  4 ); and   a second flow of gas from inlet opening  29  to extraction opening  52  and, in particular, out of first inner space  32 .       

     By providing for the first flow of gas from outlet opening  30  to inlet opening  29  it is guaranteed that web  4 , in particular first face  5 , even more particular also second face  6 , remain sterile after the sterilization as any contaminants are directed away from the sterile web  4 , in particular the sterile first face  5 , even more particular also the sterile second face  6 . 
     By providing for the second flow of gas from inlet opening  29  to extraction opening  52  contaminants and other undesired components such as ozone are removed from sterilization apparatus  9 , in particular first inner space  32 , in a controlled manner. 
     Preferentially, the aspiration device is also configured to generate a third flow of gas from second inner space  34  to advancement channel  28 , in particular from discharge mouth  56  to outlet opening  30 . 
     Preferably, the aspiration device is also configured to generate a fourth flow of gas from inner environment  15 , in particular through discharge mouth  56 , into second inner space  34 . 
     In a preferred embodiment, the aspiration device comprises a suction conduit  61  arranged within first inner space  32  and being configured to at least partially guide the second flow of gas, in particular at least to extraction opening  52 . Suction conduit  61  has an intake mouth  62  (through which, in use, the gas of the second flow of gas enters) and being arranged in the proximity of inlet opening  29 . 
     In more detail, suction conduit  61  comprises a first conduit portion  63  extending parallel to inlet opening  29  and comprising intake mouth  62  and a second conduit portion  64  being fluidically and, in particular also mechanically, connected to first conduit portion  63  and extraction opening  52 . 
     Preferentially, first conduit portion  63  also comprises a web passage  65  being arranged opposite to intake mouth  62  and being configured to allow, in use, entrance of web  4  into first conduit portion  63 . In particular, intake mouth  62  is also configured to allow for the exit of web  4  from first conduit portion  63 . In other words, in use, web passage  65  is positioned upstream of intake mouth  62 , which again is positioned upstream of inlet opening  39  along path P. 
     In even further detail, first conduit portion  63  comprises a first structured sheet  66  and a second structured sheet  67  defining in collaboration intake mouth  62  and, in particular also web passage  65 . Preferentially, first structured sheet  66  is connected to, in particular fixed to, second conduit portion  64 , and second structured sheet  67  is connected to and protrudes from first principal wall  44  into first inner space  32 . 
     Preferentially, the aspiration device also comprises at least one suction device configured to generate the suction force and being fluidically connected to second inner space  34  through a(n) (outer) tubing  68  (only partially shown) connected to first auxiliary shielding chamber  31  in the area of extraction opening  52 . Even more preferentially, the aspiration device is configured to direct the gas extracted from first auxiliary shielding chamber  31 , in particular first inner space  32 , to a regeneration circuit of packaging machine  1 . 
     In a most preferred embodiment, packaging machine  1  comprises pressure control means configured to maintain a first pressure within first auxiliary shielding chamber  31 , a second pressure within second auxiliary shielding chamber  33  and a third pressure within isolation chamber  14 . 
     Preferentially, pressure control means are configured to control the first pressure, the second pressure and the third pressure such that the second pressure is higher than the first pressure and the third pressure is higher than the second pressure. In other words, pressure control means are configured to control the first pressure, the second pressure and the third pressure such that the first pressure is lower than the second pressure and the second pressure is lower than the third pressure. 
     These pressure distributions allow to further guarantee to avoid contaminating the sterile environments within packaging machine  1 . 
     Preferentially, pressure control means are configured to control:
         the first pressure to be substantially constant, in particular to be substantially identical to the atmospheric pressure;   the second pressure to range between 10 to 60 Pa above ambient pressure, in particular between 20 to 40 Pa above ambient pressure; and   the third pressure to range between 100 to 600 Pa above ambient pressure, in particular between 200 to 400 Pa above ambient pressure.       

     In a preferred embodiment, pressure control means comprise a portion of sterilization apparatus  9 , in particular a valve  72  coupled to first auxiliary shielding chamber  31  and configured to selectively open or close so as to respectively allow or prevent a gas to enter into first auxiliary shielding chamber  31 , in particular first inner space  32 , for controlling the first pressure. 
     Preferentially, pressure control means comprise the aspiration device. 
     Pressure control means also comprise a sterile gas circuit, in particular a closed sterile gas circuit, configured to introduce sterile gas, in particular sterile air, into isolation chamber  14 . 
     With particular reference to  FIG. 4 , pressure control means also comprises a restriction group  73  configured to control the pressure drop from isolation chamber  14  to second auxiliary shielding chamber  33 . 
     Preferentially, restriction group  73  comprises two restriction sheets  74  configured to restrict the cross-sectional size of discharge mouth  56 . Even more preferentially, restriction sheets  74  are moveable for allowing to adjust the pressure drop. 
     In the specific example shown, restriction sheets are manually moveable so as to adjust the relative positions. In an alternative embodiment not shown, pressure control means could comprise an actuator configured to adjust the relative positions of restriction sheets  74 . 
     In use, packaging machine  1  forms packages  2  filled with the pourable product. 
     In more detail, a method of forming packages  2  comprises the following main steps:
         advancing web  4  along advancement path P;   sterilizing at least first face  5  of web  4  at sterilization station  10 ;   forming tube  3  at tube forming station  18 ;   longitudinally sealing tube  3 ;   filling tube  3  with the pourable product;   advancing tube  3  along path Q; and   obtaining single packages  2  from tube  3  by forming tube  3 , transversally sealing tube  3  between successive packages  2  and transversally cutting tube  3  between successive packages  2  for obtaining single packages  2 .       

     Preferentially, the method of forming packages  2  also comprises a step of controlling the pressure during which the pressure within at least sterilization apparatus  9  and isolation chamber  14  is controlled. 
     In more detail, during the main step of advancing web  4 , conveying means  22  advance web  4  from magazine unit  7  along advancement path P through sterilization apparatus  9  and to tube forming device  17 . 
     In other words, conveying means  22  advance web  4  from host station  8  to tube forming station  18  through sterilization station  10 . 
     More specifically, the main step of advancing web  4  comprises:
         a first sub-step of advancing, during which web  4  advances along deviation portion P 2 ;   a second sub-step of advancing, during which web  4  advances along sterilization portion P 1 ; and   preferentially, a third sub-step of advancing, during which web  4  advances along deviation portion P 3 .       

     Even more specifically, during the first sub-step of advancing, web  4  advances through first inner space  32  from access opening  47  to inlet opening  29 . 
     Preferentially, during the second sub-step of advancing, web  4  advances through advancement channel  28  from inlet opening  29  to outlet opening  30 . 
     Preferentially, during the third sub-step of advancing, web  4  advances through second inner space  34  from access mouth  55  to discharge mouth  56 . 
     During the main step of forming tube  3 , tube forming device  17  gradually overlaps the opposite lateral edges of web  4  with one another so as to form a longitudinal seam portion. 
     During the main step of longitudinally sealing tube  3 , sealing device  19  seals the longitudinal seam portion. 
     During the main step of advancing tube  3 , conveying means  22  advance tube  3  (and any intermediates of tube  3 ) along path Q to package forming unit  21 . 
     During the main step of filling tube  3 , filling means  20  fill the pourable product into the longitudinally sealed tube  3 . 
     During the main step of obtaining single packages  2 , package forming unit  21  forms and transversally seals tube  3  between successive packages  2  and, preferentially, also transversally cuts tube  3  between successive packages  2 . 
     In more detail, during the main step of sterilizing web  4 , at least a step of directing a sterilizing irradiation, in particular electromagnetic irradiation, even more particular electron beam irradiation, at least onto first face  5 , preferentially also onto second face  6  is executed. 
     Preferentially, during the main step of sterilizing web  4 , the first sub-step of advancing and the second sub-step of advancing, even more preferentially also the third sub-step of advancing, are executed. 
     Preferentially, during the step of directing a sterilization irradiation, irradiation device  26  directs the sterilizing irradiation, in particular the electromagnetic irradiation, even more particular the electron beam irradiation, at least onto first face  5 , preferentially also onto second face  6  for sterilizing first face  5  and, preferentially also second face  6 . 
     In even more detail, during the step of directing a sterilization irradiation, first electron beam emitter  35  directs the electron beam irradiation onto first face  5 , and preferentially second electron beam emitter  36  directs the electron beam irradiation onto second face  6  while web  4  is advanced through advancement channel  28  along sterilization portion P 1 . 
     Preferentially, the step of directing a sterilization irradiation is executed during the second sub-step of advancing. 
     Preferentially, during the main step of sterilizing web  4  also a step of generating a first flow of gas within advancement channel  28  from outlet opening  30  to inlet opening  29  and a second flow of gas from inlet opening  29  to extraction opening  52  are executed and, in particular gas is extracted from first inner space  32 . 
     In more detail, during the step of generating, the second flow of gas flows at least partially through suction conduit  61 . Preferentially, the second flow of gas enters suction conduit  61  through intake mouth  62  and flows to extraction opening  52 . Even more preferentially, after entering the suction conduit  61 , the second flow of gas flows through first conduit portion  63  and then through second conduit portion  64 . Then, the second flow of gas is removed from first inner space  32  through extraction opening  52 . 
     In even further detail, during the step of generating, the suction device generates the suction force for generating the first flow of gas and the second flow of gas. Preferentially, the gas is extracted from first inner space  32  through extraction opening  52  and into tubing  68 . Even more preferentially, the gas extracted from first inner space  32  is directed into the regeneration circuit. 
     Advantageously, during the step of controlling the pressure, the pressure control means control the first pressure, the second pressure and the third pressure such that the first pressure is lower than the second pressure and the second pressure is lower than the third pressure. 
     Preferentially, the pressure control means control the pressures such that:
         the first pressure is substantially constant, in particular substantially identical to the atmospheric pressure;   the second pressure ranges between 10 to 60 Pa above ambient pressure, in particular between 20 to 40 Pa above ambient pressure; and   the third pressure ranges between 100 to 600 Pa above ambient pressure, in particular between 200 to 400 Pa above ambient pressure.       

     More specifically, the first pressure is controlled through valve  72 . Valve  72  opens to guide a gas into first auxiliary chamber  31  if the first pressure falls below a predetermined pressure value, in particular below atmospheric pressure. The latter case may occur in these cases in which the suction force applied by the suction device would extract gas from first inner space  32  in an amount being larger than the gas entering into first inner space  32  through inlet opening  29 . 
     Preferentially, pressure control means control the third pressure through the sterile gas circuit introducing sterile gas into isolation chamber  14 . 
     Preferentially, the pressure drop between isolation chamber  14  and second auxiliary shielding chamber  33  is controlled by restriction group  73  and the first flow of gas within advancement channel  28  generating a third flow of gas from second inner space  34  towards advancement channel  28 , in particular from discharge mouth  56  to outlet opening  30 . 
     The advantages of sterilization apparatus  9  according to the present invention will be clear from the foregoing description. 
     In particular, sterilization apparatus  9  comes along with a simplified structure with respect to the ones known in the art. 
     Even more particular, sterilization apparatus  9  allows to clearly define the aseptic environments of packaging machine  1  by controlling the third pressure, the second pressure and the first pressure. By providing for the third pressure being higher than the second pressure it is avoided that gas from second inner space  34  enters into inner environment  15 . Furthermore, by providing for the second pressure being higher than the first pressure it is guaranteed that any contaminations are directed into first inner space  32  and not into second inner space  34 . The latter is further guaranteed by providing for the first flow of gas from outlet opening  30  to inlet opening  29  actively actuated by the aspiration device. 
     Clearly, changes may be made to sterilization apparatus  9  as described herein without, however, departing from the scope of protection as defined in the accompanying claims.