EP4345013A1

EP4345013A1 - Machine for producing containers filled with a product and sealed

Info

Publication number: EP4345013A1
Application number: EP23198458.4A
Authority: EP
Inventors: Fabio BIRELLO; Alessandro CRISTOFORI; Giovanni SORICELLI; Enrico Bernardi
Original assignee: Ipi SRL
Current assignee: Ipi SRL
Priority date: 2022-09-30
Filing date: 2023-09-20
Publication date: 2024-04-03
Also published as: CN117799919A

Abstract

Described herein is a machine (10) for producing containers (110) filled with a product and sealed starting from a web (100) of packaging material.

The machine comprises a drying chamber (40) and a forming chamber (60), which are set in mutual communication via a primary passage (50) and a secondary passage (52), which itself also sets in mutual fluid communication said drying chamber (40) and said forming chamber (60) according to a configuration in parallel with respect to said primary passage (50).

The machine further comprises a valve (56) for controlling a flow of air that traverses said secondary passage (52).

Description

Field of the invention

The present invention regards a machine for producing containers filled with a product and sealed, starting from a web of packaging material.
In particular, the present invention regards a machine of the type comprising:

a web-feed system for feeding the web of packaging material along a work path;
a tank, set along the work path, for containing a bath immersed in which is the web of packaging material that advances along the work path;
a drying chamber, which is set downstream of the tank along the work path, is in fluid communication with said tank, and is equipped with at least one drying device for drying the web of packaging material that advances along the work path; and
a forming chamber, which is set downstream of the drying chamber along the work path, is in fluid communication with said drying chamber, and is equipped with a forming device for forming the web so as to obtain the containers.

The machine according to the present invention likewise comprises a primary passage, for example a slit or an opening or a bypass duct, which extends along the work path and connects together the drying chamber and the forming chamber, a compression unit for supplying pressurized air into the forming chamber, and an air-suction unit, which is connected to the drying chamber.
During its operation, a machine of the type referred to above is frequently subjected to cleaning and sterilization cycles, typically, but not exclusively, at each end of production, which is followed, in particular, by a machine stoppage, in order to restore therein an aseptic production environment.
The sterilization cycle of the drying and forming chambers referred to above is carried out using peroxide steam mixed with air.
The present applicant has been able to note that the containers produced by the machine may at times not meet the requisites of sterilization envisaged, notwithstanding the cleaning and sterilization cycles systematically conduction prior to start of a new production cycle.
The sterilization cycle using peroxide steam conducted for the drying chamber and the forming chamber requires the temperature of the walls of each chamber to be below the dew point of the peroxide steam in order to guarantee that the peroxide will wet the aforesaid walls and will thus bring about an effective action of sterilization.
In order to bring the inner walls of the above chambers to temperatures below the dew point of the peroxide steam, it is known to introduce cooling air into the chambers through the same air-conveying system that, in the production cycle of the machine, is designed to set up controlled pressures in the chambers themselves.
The present applicant has noted that the action of cooling thus obtained may not be sufficient to guarantee reaching of sufficiently low temperatures inside the above chambers, so that the subsequent operation of sterilization, conducted using peroxide steam, may in turn not prove effective.
The present applicant has hence understood that it is necessary to provide an improved operation of cooling of the two chambers to solve the aforesaid technical problem regarding production of containers that meet the sterilization requisites envisaged.
In the above context, the present applicant has, however, understood that, instead of providing a new cooling system, it is possible to overcome the limits referred to above of the conventional cooling operation by balancing in a different way the flow of air during the cooling operation.
In the present description, as likewise in the claims annexed thereto, some terms and expressions are to be considered, except where otherwise explicitly indicated, as having the meaning given in the ensuing definitions.
In an apparatus or unit for processing an object that advances in a direction of feed along a work path, a first position is said to be "upstream" of a second position when the first position precedes the second position with reference to the direction of feed of the object; vice versa, the second position is said to be "downstream" of the first position in so far as it follows the first position once again with reference to the direction of feed of the object.
The term "passage" used herein refers generically to a path of flow for a fluid, for example air.
With reference to fluid-dynamics, two or more passages through which a fluid can flow are connected according to a configuration "in parallel" when, between their ends, there is the same pressure difference; in this case, the reciprocal of the total resistance at the ends of the ducts will be equal to the sum of the reciprocals of the individual resistances of each duct.
According to a first aspect, the present invention concerns a machine for producing containers filled with a product and sealed, starting from a web of packaging material.
The machine preferably comprises a system for supplying said web of packaging material, in particular for feeding said web of packaging material along a work path.
The machine preferably comprises a tank. The tank is preferably set along said work path, in particular for containing a bath immersed in which is said web of packaging material that advances along said work path.
The machine preferably comprises a drying chamber. Preferably, the drying chamber is set downstream of said tank along said work path. Preferably, the drying chamber is in fluid communication with said tank. Preferably, the drying chamber is equipped with at least one drying device, in particular for drying said web of packaging material that advances along said work path.
The machine preferably comprises a forming chamber. Preferably, the forming chamber is set downstream of said drying chamber along said work path. Preferably, the forming chamber is in fluid communication with said drying chamber. Preferably, the forming chamber is equipped with a forming device, in particular for forming said web so as to obtain said containers.
The machine preferably comprises a primary passage. Preferably, the primary passage extends along the work path, in particular for passage of the web of packaging material. Preferably, the primary passage connects together the drying chamber and the forming chamber.
The machine preferably comprises a compression unit, in particular for supplying pressurized air into said forming chamber.
The machine preferably comprises an air-suction unit. Preferably, the air-suction unit is connected to said drying chamber. Preferably, the air-suction unit is connected to said tank.
The machine preferably comprises a secondary passage. Preferably, said secondary passage sets in mutual fluid communication said drying chamber and said forming chamber, in particular according to a configuration in parallel with respect to said primary passage.
The machine preferably comprises a valve for controlling the flow of air that traverses said secondary passage.
The secondary passage, set in parallel with respect to the primary passage, sets in mutual communication the drying chamber and the forming chamber. Such a secondary passage is able to increase the flow of air through the two chambers, particularly during the cooling operation, thus bringing about an action of cooling of the two chambers that is more efficient and effective. Thanks to the aforesaid characteristics, the machine is thus able to achieve an optimal operation of cooling of the forming chamber and of the drying chamber, and subsequently an effective sterilization process or an effective cleaning process within the chambers themselves.
According to a second aspect, the present invention regards a method for operating a machine according to the aforesaid first aspect of the invention.
The method preferably comprises the step of detecting a state signal indicating an operating state of the machine.
The method preferably comprises the step of controlling said valve to determine a maximum section of flow, in particular when the state signal detected indicates one between a process of cleaning and a process of sterilization of the machine.
The method preferably comprises the step of supplying pressurized air into said forming chamber, in particular until, inside said forming chamber and said drying chamber, a temperature equal to or lower than a reference temperature is reached.
The method preferably comprises the step of introducing into said forming chamber a steam, preferably a sterilizing steam, in an equally preferred way having a dew point higher than or equal to said reference temperature.
Thanks to the aforesaid characteristics, it is possible to obtain an optimal operation of cooling of the forming chamber and of the drying chamber, and subsequently an effective sterilization process or an effective cleaning process within the chambers themselves.
According to one or more of the aforesaid aspects, the present invention may comprise one or more of the characteristics described in what follows.
In one or more embodiments, the machine comprises a control unit. Preferably, said control unit is configured for controlling said valve, in particular as a function of a state signal indicating an operating state of the machine.
Thanks to the aforesaid characteristics, the machine described herein is able to carry out automatic control of the state of the valve.
In one or more embodiments, the machine comprises a memory unit. Preferably, stored in the memory unit is a set of operating parameters of said valve. Preferably, each operating parameter of said set is designed to determine a given section of flow of said valve.
In one or more embodiments, said set of operating parameters comprises at least one first operating parameter. Preferably, the first operating parameter determines a maximum section of flow of said valve. In one or more embodiments, said set of operating parameters comprises at least one second operating parameter. Preferably, the second operating parameter determines a reduced section of flow of said valve. Preferably, said reduced section of flow is smaller than said maximum section of flow.
In one or more embodiments, said control unit is configured for extracting from said memory unit said first operating parameter and operating said valve according to said first operating parameter, preferably when said state signal indicates one between a process of cleaning and a process of sterilization of the machine. In one or more embodiments, said control unit is configured for extracting said second operating parameter and operating said valve according to said second operating parameter, preferably when said state signal indicates a production state of the machine.
Thanks to the aforesaid characteristics, the machine described herein is able to carry out a simple and reliable control of the valve.
In one or more embodiments, said secondary passage comprises a bypass duct. Preferably, the bypass duct connects together the drying chamber and the forming chamber. Preferably, the bypass duct extends alongside said primary passage. Preferably, the bypass duct comprises an inlet. Preferably, the inlet of the bypass duct sets the forming chamber and the bypass duct in fluid communication. Preferably, said valve comprises an open/close element; preferably, the open/close element is set at said inlet. Preferably, the open/close element is mobile, in particular for varying a section of flow of said valve set between said inlet and said forming chamber.
Thanks to the aforesaid characteristics, it is possible to obtain a secondary passage without noticeably complicating the structure of the machine.
In one or more embodiments, said open/close element is formed by a flap that is rotatable about an axis of rotation.
In one or more embodiments, the machine comprises a sensor, in particular for detecting a pressure inside said drying chamber. In one or more embodiments, said control unit is connected to said suction unit. Preferably, said control unit is configured for starting a calibration step, in particular as a function of the state signal. Preferably, the control unit is configured for varying, during said calibration step, at least one operating parameter of said suction unit, for example as a function of a pressure signal, in particular for identifying an effective value of said operating parameter. Preferably, the pressure signal indicates the pressure detected inside the drying chamber. Preferably, the effective value of the operating parameter determines a desired pressure inside the drying chamber.
Preferably, the control unit is configured for operating, during operation of the machine, the suction unit, with the operating parameter of the suction unit set substantially at said identified effective value.
Thanks to the aforesaid characteristics, the machine is able to identify automatically an optimal setting thereof that will take into account all the specificities of the installation layout of the machine and of the working environment in which the machine is installed.
In one or more embodiments, the primary passage comprises a drying tunnel. Preferably, the drying tunnel is configured for drying the web that advances along said work path.
In one or more embodiments, the method comprises the step of controlling said valve to determine a reduced section of flow with respect to said maximum section of flow, in particular when the state signal detected indicates a production state of the machine.
In one or more embodiments, the method comprises the step of supplying pressurized heated air into the forming chamber via the compression unit.
In one or more embodiments, the method comprises the step of drawing air from the drying chamber via the suction unit.
In one or more embodiments, the method comprises the step of feeding the web of packaging material along the work path.
In one or more embodiments, the method comprises the step of immersing the web of packaging material in the bath contained in the tank.
In one or more embodiments, the method comprises the step of drying the web of packaging material inside the drying chamber.
In one or more embodiments, the method comprises the step of forming the web inside the forming chamber, in particular to obtain the containers.
Thanks to the aforesaid characteristics, it is possible to obtain a production cycle that is able to guarantee a total sterility of the containers produced.
In one or more embodiments, the method comprises the step of starting a calibration step, in particular as a function of the state signal.
In one or more embodiments, the method comprises the step of detecting a pressure inside the drying chamber.
In one or more embodiments, the method comprises, during the calibration step, the step of varying at least one operating parameter of said suction unit, in particular as a function of a pressure signal, for example indicating the pressure inside the drying chamber, in particular to identify an effective value of the operating parameter, the latter preferably determining a desired pressure inside the drying chamber.
In one or more embodiments, the method comprises, during operation of said machine, the step of operating the suction unit, with the operating parameter of said suction unit set substantially at said identified effective value.
Thanks to the aforesaid characteristics, the machine is able to identify automatically an optimal setting thereof that will take into account all the specificities of the installation layout of the machine and of the working environment in which the machine is installed.
In one or more embodiments, the calibration step is started when said state signal indicates one between a state of starting of the machine and a state in which the bath is absent from the tank.
In one or more embodiments, the method includes controlling the compression unit as a function of a flow-rate signal. Preferably, the flow-rate signal indicates a reference flow rate of air.
In one or more embodiments, the step of controlling the valve includes the step of providing a control unit, in particular configured for controlling the valve.
In one or more embodiments, the step of controlling the valve includes the step of providing a memory unit. Preferably, the memory unit contains at least one first operating parameter that determines a maximum section of flow of the valve. Preferably, the memory unit contains at least one second operating parameter that determines a reduced section of flow of the valve. Preferably, the reduced section of flow is smaller than the maximum section of flow.
In one or more embodiments, the step of controlling the valve includes, when said control unit receives the state signal indicating one between a process of cleaning and a process of sterilization of the machine, the steps of extracting from the memory unit the first operating parameter of the valve and operating said valve according to said first operating parameter.
In one or more embodiments, the step of controlling the valve includes, when the control unit receives the state signal indicating a production state of the machine, the steps of extracting from the memory unit a second operating parameter of the valve and operating said valve according to said second operating parameter.
Thanks to the aforesaid characteristics, it is possible to carry out a simple and reliable control of the valve.
It is pointed out that some steps of the method described above may be independent of the order of execution referred to, except where there is expressly indicated as necessary a sequentiality or simultaneity between two or more steps. Moreover, some steps may be optional. Moreover, some steps may be carried out in a repetitive way, or else may be carried out in series or in parallel with other steps of the method.
Further characteristics and advantages of the present invention will emerge clearly from the ensuing description, with reference to the annexed drawings, which are provided purely by way of non-limiting example and in which:

Figure 1 is a schematic illustration of the machine described herein according to a preferred embodiment; and
Figure 2 illustrates a detail of a component of the machine of Figure 1.

As indicated above, the machine described herein operates for producing containers filled with a product and sealed, starting from a web of packaging material.
The product may preferably be a liquid or else a granular material.
With reference to the preferred embodiment of Figure 1, the machine described herein and designated as a whole by the reference number 10 comprises a system for supplying a web 100 of packaging material, which is able to feed the web 100 along a work path K. Preferably, the web 100 is fed from a reel (not illustrated) and develops as a single continuous web along the entire work path K.
The machine 10 comprises a tank 20 that is set along the work path K and contains a bath 20' (illustrated with a dashed line) immersed in which is the web 100 that advances along the work path K.
Preferably, the bath 20' is constituted by a sterilizing and/or sanitizing liquid.
In one or more preferred embodiments, like the one illustrated, the tank 20 has a generic U shape, comprising a first branch 22A, upstream, a second branch 22B, downstream, and a bottom region 22C, which connects the two branches and housed within which is a deflector roller 12, belonging to the system for feeding the web 100 and configured to determine a reversal of the direction of advance of the web 100 (from a top-down direction to a bottom-up direction).
Provided above the first branch 22A is a chamber 30, which constitutes a top region of the tank 20, whereas extending above the second branch 22B is a drying chamber 40 for drying the web 100 after it has come out of the bath 20'.
It should be noted that the chamber 30 and the drying chamber 40 do not communicate directly with one another, but are instead connected to one another only through interposition of the tank 20. In operation, the presence of the bath 20' prevents any passage of air between the drying chamber 40 and the chamber 30.
In a way in itself known, the drying chamber 40 is equipped with a series of drying devices configured for drying two opposite faces 100A, 100B of the web 100 that advances inside the drying chamber 40 along the work path K. For instance, the drying chamber 40 may comprise a pair of opposed squeezing rollers 42, which operate for compressing the web 100, in a direction transverse to the work path K, so as to expel the liquid absorbed by the web 100 in the bath 20'. Moreover, the drying chamber 40 may comprise a pair of heads 44 for delivery of air, preferably heated air, which are arranged on the two opposite sides of the web 100, to deliver a jet of air against the opposite faces 100A, 100B of the web 100.
Downstream of the drying chamber 40, along the work path K, the machine 10 comprises a forming chamber 60, within which the web 100 is formed to obtain the containers 101 filled with product and sealed.
In one or more preferred embodiments, like the one illustrated, the forming chamber 60 is provided with a forming device for curling the web 100 to form a tube about an axis I that extends in a direction parallel to the work path K inside the forming chamber 60 itself. Moreover, provided within the forming chamber 60 are sealing means for fixing together the opposite longitudinal edges of the web 100 so as to close the web 100 and obtain a vertical tube 102 sealed laterally.
The tube 102 is filled with the product to be packaged and extends downwards until it reaches a further chamber 80, set downstream of the forming chamber 60. In this further chamber, on the tube 102 filled with the product there are provided transverse sealing bands that identify, on the tube 102 itself, single containers 110, which are then cut off the tube 102.
The means to implement the steps described above of forming, sealing, and cutting may be of a known type, and consequently they will not be described in detail herein so as not to burden the present treatment.
In one or more preferred embodiments, like the one illustrated, the machine 10 further comprises a primary passage 50 that extends along the work path K and connects together the drying chamber 40, in particular a downstream end thereof 40B, and the forming chamber 60, in particular an upstream end thereof 60A. The primary passage 50 is pre-arranged for passage of the web 100 from the drying chamber 40 to the forming chamber 60.
In one or more preferred embodiments, like the one illustrated, the machine 10 comprises a compression unit 72 for supplying pressurized air into the forming chamber 60, and an air-suction unit 74, which is connected to the top chamber 30 and to the drying chamber 40.
In a normal production cycle of the machine, the compression unit 72 and the air-suction unit 74 determine a flow of air that is introduced into the forming chamber 60, traverses the primary passage 50, reaches the drying chamber 40, and is finally drawn out by the suction unit 74.
The above flow of air is designed to determine predefined environmental pressures in the drying chamber 40 and in the forming chamber 60 themselves. Advantageously, within the primary passage 50 said flow of air may likewise carry out a further action of drying of the web 100 via a process of heat exchange by convection.
As mentioned at the start, after a machine stoppage there may be the need to carry out an operation of sterilization of the machine before starting a new production cycle, which, for the drying chamber 40 and the forming chamber 60, envisages the use of peroxide steam mixed with air. Preliminarily, it is necessary to cool the inner walls of the two chambers in order to bring them to a temperature below the dew point of the peroxide steam.
For this purpose, the compression unit 72 and the air-suction unit 74 are operated to circulate cooling air through the drying chamber 40 and the forming chamber 60 so as to reduce the temperature of their inner walls.
According to an important characteristic of the solution described herein, the machine 10 comprises a secondary passage 52 that sets the drying chamber 40 and the forming chamber 60 in communication with one another and that is arranged according to a configuration in parallel with respect to the primary passage 50. Moreover, the machine comprises a valve 56 for controlling the flow of air that traverses the secondary passage 52.
The secondary passage 52 may advantageously be used during the cooling operation so that it will be traversed by a flow of air parallel to the flow that traverses the primary passage 50 in order to determine as a whole an optimal flow rate of air for cooling the drying chamber 40 and the forming chamber 60 rapidly and to the desired temperatures, below the dew point of the peroxide steam.
On the other hand, during a normal production cycle of the machine, the secondary passage 52 may be substantially closed by the valve 56 (in particular, the valve allows passage of an amount of air that is extremely small and hence negligible for the purposes of the fluidic balance) or else may be traversed by a predefined flow of air, this according to the requirements of the specific applications.
In one or more preferred embodiments, like the one illustrated, the secondary passage 52 comprises a bypass duct 54, which connects the drying chamber 40 and the forming chamber 60 and extends alongside the primary passage 50. The bypass duct 54 comprises an inlet opening 54A, which sets in fluid communication the forming chamber 60 and the bypass duct 54 and on which the valve 56 is set. Alternatively, the valve 56 may be set within the bypass duct 54 or else at an outlet thereof that sets it in communication with the drying chamber 40.
The valve 56 comprises a mobile open/close element 56C for varying a section of flow of the valve, this being defined through an opening 56B made in the body 56A of the valve and mating with the inlet opening 54A of the bypass duct 54. In one or more embodiments, the open/close element 56C is formed by a flap that is rotatable about an axis of rotation.
In one or more preferred embodiments, like the one illustrated, the machine comprises a control unit 90 configured for controlling the valve as a function of a state signal W1 indicating a state of operation of the machine.
In one or more preferred embodiments, like the one illustrated, the machine comprises a memory unit 92, stored in which is a set of operating parameters of the valve, in particular comprising a first operating parameter V1, which defines a maximum section of flow of the valve, and a second operating parameter V2, which defines a reduced section of flow of the valve.
The control unit 90 is configured for extracting the first operating parameter V1 and controlling the valve on the basis thereof when it receives a state signal W1 indicating a process of cleaning and/or sterilization of the machine, and for extracting the second operating parameter V2 and controlling the valve on the basis thereof when it receives a state signal W1 indicating a normal production cycle of the machine.
The control unit 90, or a further control unit of the machine, is configured for controlling also operation of the compression unit 72 and of the suction unit 74.
The compression unit 72 and the air-suction unit 74 may both be constituted by a compressor of a conventional type.
Preferably, the compression unit 72 is controlled as a function of a signal indicating the flow rate for generating a flow of air characterized by a reference flow rate.
On the other hand, the suction unit 74 is preferably controlled on the basis of an operating parameter identified via an automatic calibration step carried out by the machine.
Preferably, said calibration step envisages a procedure where an operating parameter of the suction unit 74 is varied as a function of a pressure signal W3 indicating the pressure inside the drying chamber 40 and until a value of said operating parameter is reached that determines a pressure inside the drying chamber 40 itself equal to a desired pressure.
The value of the operating parameter thus reached is hence identified as effective value of the operating parameter of the suction unit 74 and stored as such in the memory unit 92, then to be used during normal operation of the machine.
The operating parameter in question may, for example, be a speed of rotation of a rotor of the suction unit 74.
The control unit 90 may be configured for implementing the aforesaid calibration step.
Preferably, the pressure signal W3 is obtained by a pressure sensor 94 configured for detecting the pressure inside the drying chamber 40.
The aforesaid calibration step is started automatically by the machine when it is in a given operating state.
For this purpose, the control unit 90 may be configured for starting the calibration step on the basis of the state signal W1 itself referred to above, in particular when the state signal W 1 indicates a step of start of the machine, for example the first start-up after installation or else a start-up after a prolonged machine stoppage.
The aforesaid calibration step enables the machine to identify automatically an optimal setting thereof, taking into account all the specificities of the installation layout of the machine and of the working environment in which the machine is installed.
Of course, without prejudice to the principle of the invention, the details of construction and the embodiments may vary, even significantly, with respect to what has been illustrated herein purely by way of non-limiting example, without thereby departing from the scope of the invention, as defined by the annexed claims.

Claims

A machine (10) for producing containers (110) filled with a product and sealed, starting from a web (100) of packaging material, said machine (10) comprising:
- a web-feed system for feeding said web (100) along a work path (K);

- a tank (20), set along said work path (K), for containing a bath (20') immersed in which is said web (100) that advances along said work path (K);

- a drying chamber (40), which is set downstream of said tank (20) along said work path (K), is in fluid communication with said tank (20), and is equipped with at least one drying device for drying said web (100) that advances along said work path (K); and

- a forming chamber (60), which is set downstream of said drying chamber (40) along said work path (K), is in fluid communication with said drying chamber (40), and is equipped with a forming device for forming said web (100) so as to obtain said containers (110);

- a primary passage (50), which extends along said work path (K) for passage of said web (100) and connects together said drying chamber (40) and said forming chamber (60);

- a compression unit (72) for supplying pressurized air into said forming chamber (60);

- an air-suction unit (74), which is connected to said drying chamber (40);

- a secondary passage (52), which sets in mutual fluid communication said drying chamber (40) and said forming chamber (60) according to a configuration in parallel with respect to said primary passage (50); and

- a valve (56) for controlling a flow of air that traverses said secondary passage (52).
The machine according to claim 1, comprising a control unit (90) configured for controlling said valve (56) as a function of a state signal (W1) indicating an operating state of the machine.
The machine according to claim 1 or claim 2, comprising a memory unit (92) stored in which is a set of operating parameters (V1, V2) of said valve (56), each operating parameter (V1, V2) of said set being designed to determine a given section of flow of said valve (56).
The machine according to claim 3, wherein said set of operating parameters comprises at least one first operating parameter (V1) that determines a maximum section of flow of said valve (56), and at least one second operating parameter (V2) that determines a reduced section of flow of said valve (56), said reduced section of flow being smaller than said maximum section of flow.
The machine according to claim 4, wherein said control unit (90) is configured for extracting from said memory unit (92) said first operating parameter (V1) and for operating said valve (56) according to said first operating parameter (V1) when said state signal (W1) indicates one between a process of cleaning and a process of sterilization of the machine, and for extracting said second operating parameter (V2) and operating said valve (56) according to said second operating parameter (V2) when said state signal (W1) indicates a production state of the machine.
The machine according to any one of the preceding claims, wherein said secondary passage (52) comprises a bypass duct (54), which connects said drying chamber (40) and said forming chamber (60) and extends alongside said primary passage (50), wherein said bypass duct (54) comprises an inlet (54A) that sets in fluid communication said forming chamber (60) and said bypass duct (54), said valve (56) comprising an open/close element (56C) set at said inlet (54A) and mobile for varying a section of flow of said valve (56) set between said inlet (54A) and said forming chamber (60).
The machine according to claim 6, wherein said open/close element (56C) is formed by a flap that is rotatable about an axis of rotation.
The machine according to any one of claims 2 to 7, further comprising a sensor (94) for detecting a pressure inside said drying chamber (40), wherein said control unit (90) is connected to said suction unit (74) and is configured for:
- starting a calibration step as a function of said state signal (W1);

- during said calibration step, varying at least one operating parameter of said suction unit (74) as a function of a pressure signal (W3) indicating said pressure detected inside said drying chamber (40) to identify an effective value of said operating parameter that determines a desired pressure inside said drying chamber (40); and

- during operation of said machine, operating said suction unit (74) with said operating parameter of said suction unit (74) set substantially at said identified effective value.
A method for operating a machine according to any one of the preceding claims, comprising the steps of:
- detecting a state signal (W1) indicating an operating state of the machine;

- when said detected state signal (W1) indicates one between a process of cleaning and a process of sterilization of the machine, controlling said valve (56) to determine a maximum section of flow;

- supplying pressurized air into said forming chamber (60) until, inside said forming chamber (60) of said drying chamber (40), a temperature equal to or lower than a reference temperature is reached; and

- introducing into said forming chamber (60) a sterilizing steam having a dew point higher than or equal to said reference temperature.
The method according to claim 9, comprising the steps of:
- when said detected state signal (W1) indicates a production state of the machine, controlling said valve (56) to determine a section of flow that is reduced with respect to said maximum section of flow;

- supplying pressurized heated air into said forming chamber (60) via said compression unit (72);

- drawing air from the drying chamber (40) via said suction unit (74); and

- drying said web (100) of packaging material inside said drying chamber (40).
The method according to claim 9 or claim 10, further comprising:
- starting a calibration step as a function of said state signal (W1);

- detecting a pressure inside said drying chamber (40);

- during said calibration step, varying at least one operating parameter of said suction unit (74) as a function of a pressure signal (W3) indicating said pressure detected inside said drying chamber (40) to identify an effective value of said operating parameter that determines a desired pressure inside said drying chamber (40); and

- during operation of said machine (10), operating said suction unit (74) with said operating parameter of said suction unit (74) set substantially at said identified effective value.
The method according to claim 11, wherein said calibration step is started when said state signal (W1) indicates one between a state of starting of said machine (10) and a state in which said bath is absent from said tank (20).
The method according to any one of claims 9 to 12, which includes controlling said compression unit (72) as a function of a flow-rate signal indicating a reference flow rate of air.
The method according to any one of claims 9 to 13, wherein controlling said valve includes:
- providing a control unit (90) configured for controlling said valve (56);

- providing a memory unit (92) containing at least one first operating parameter (V1) that determines a maximum section of flow of said valve (56), and at least one second operating parameter (V2) that determines a reduced section of flow of said valve (56), said reduced section of flow being smaller than said maximum section of flow;

- when said control unit (90) receives said state signal (W1) indicating one between a process of cleaning and a process of sterilization of the machine, extracting from said memory unit (92) said first operating parameter (V1) of said valve (56) and operating said valve (56) according to said first operating parameter (V1); and

- when said control unit (90) receives said state signal (W1) indicating a production state of the machine, extracting from said memory unit (92) a second operating parameter (V2) of said valve (56) and operating said valve (56) according to said second operating parameter (V2).