TECHNICAL FIELD
-
The present invention relates to a centring device for centring a packaging film, in particular intended to be operatively mounted on a forming unit of a packaging machine.
-
More in detail, the centring device according to the invention is part of the production and marketing of apparatuses, devices, equipment, and more generally of functional units intended to be mounted on automatic packaging machines, in particular both of the horizontal type (HFFS) and of the vertical type (VFFS).
-
The centring device according to the invention is specifically intended to operate on a packaging material of the flexible film type made of a polymeric material (e.g. polyethylene, polypropylene, and others) intended to be shaped and subsequently heat-sealed to make a sealed wrapper, in particular of the square or rectangular bottom type, around one or more products to be packaged of various kinds (i.e. a package of the type referred to in the technical jargon of the sector with the term "stand-up pouch").
BACKGROUND OF THE INVENTION
-
It is known, in the technical field of reference, to use forming units for a flexible packaging film associated with and/or operatively mounted on a packaging machine, for example of the type briefly mentioned above.
-
More specifically, such forming units are configured to shape the packaging film so as to give it a predefined shape corresponding to the shape of a desired package (for example a "stand-up pouch" package as mentioned above), before a final sealing or closure thereof, thus making a sealed package.
-
Typically, such forming units comprise conveying means for conveying a flexible packaging film, for example an elongated metal body extending along a sliding direction of the packaging film (i.e. parallel to the ground), and forming means movable along a transverse direction towards and/or away from the conveying means in order to come into contact with the packaging film and give it a predefined and desired shape depending on the type of package to be made.
-
The forming units of the type known so far briefly described have proved to be not without drawbacks in practice.
-
In particular, the main drawback lies in the fact that the forming units for packaging machines of the known type do not allow to keep the packaging film stable while it is sliding through the forming unit itself.
-
In fact, due to errors during the assembly of the mechanical members and of the components constituting the forming unit, lateral skiddings or slips of the packaging film may occur with respect to its predefined sliding axis and substantially corresponding to the direction of extension of the the conveying means. In addition to this, errors may also occur in the assembly and/or positioning of the means for unwinding and feeding the packaging film to the forming unit.
-
These errors aggravate and further amplify any deviations of the sliding film with respect to its predefined motion along the sliding axis, resulting in a forced stop of the packaging machine with which the forming unit is associated for a repositioning and/or realignment of the packaging film.
-
It follows that the forming units, and therefore the packaging machines with which these units are associated, are unreliable as they require periodic checks by qualified personnel in order to guarantee a correct operation thereof over time (i.e. for a high number of cycles corresponding to the production of a high number of packages in the unit of time).
-
What has just been described is amplified and therefore more burdensome for forming units mounted on automatic high-speed packaging machines, that is, capable of producing a number of packages every hour higher than a standard average value.
OBJECTS OF THE INVENTION
-
The object of the present invention is to provide a centring device for centring a packaging film for a forming unit of a packaging machine that makes it possible to overcome the drawbacks of the the prior art.
-
A further object of the present invention is to provide a centring device that allows the packaging film to be kept in a centred position, i.e. substantially astride a packaging direction (i.e. a film sliding direction), during the movement of the film itself, without skidding or deviations or lateral slippages of the packaging film occurring with respect to the the packaging direction.
-
In other words, the object of the present invention is to provide a centring device that allows a stable, precise and reliable positioning of the film during the movement thereof in the packaging process.
-
A further object of the present invention is to provide a centring device that is functionally and structurally simple and economical.
-
A further object of the present invention is to provide a centring device that is applicable to a forming unit of a packaging machine in a simple, fast and low-cost manner.
SUMMARY
-
All the objects, either individually or in any combination thereof, and others that will emerge from the detailed description that follows are achieved, according to the invention, with a centring device for centring a packaging film for a forming unit of a packaging machine having the features indicated in independent claim 1.
-
The dependent claims outline particularly advantageous embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
-
Additional features and advantages of the present invention will appear clearer from the indicative, and therefore not limiting, description of a preferred but not exclusive embodiment of a centring device for centring a packaging film for a forming unit of a packaging machine, as illustrated in the accompanying drawings, wherein:
- figure 1 shows, according to a perspective view, a centring device for centring a packaging film in a configuration mounted on a forming unit of a packaging machine, according to an embodiment of the invention;
- figure 2 shows, according to a longitudinal sectional view, the centring device illustrated in figure 1;
- figure 3 shows, according to a detailed perspective view, the centring device illustrated in figure 1;
- figure 4A shows, according to a side view, the centring device illustrated in figure 3;
- figure 4B shows, according to a front view, the centring device illustrated in figure 3;
- figure 4C shows, according to a top plan view, the centring device illustrated in figure 3.
-
It should be noted that the drawings serve solely to illustrate embodiments of the invention with the aim of better clarifying, in combination with the description, the inventive principles at the basis of the invention.
DETAILED DESCRIPTION OF THE INVENTION
-
With reference to the attached figures, a centring device for centring a packaging film for a forming unit of a packaging machine according to the present invention has been indicated overall with the number 100.
-
In the following description, specific reference will be made to a centring device 100 operatively installed in a forming unit of an automatic packaging machine of the horizontal type (called in the technical jargon of the sector with the acronym HFFS, i.e. Horizontal Form Fill and Seal) and intended to make packages of the square or rectangular bottom type (i.e. "stand-up pouch").
-
However, the the centring device 100 can also be installed in other configurations of packaging machines, for example machines of the vertical type (VFFS, i.e. Vertical Form Fill and Seal) and intended to make various types of packages, without thereby falling outside the scope of protection of the invention.
-
The term "packaging film" shall mean a film in a flexible polymeric material (for example polyethylene, polypropylene, multilayer, and others still commonly used in the the technical field and well known to a person skilled in the art) adapted to be suitably folded and heat-sealed, so as to make a sealed closed package containing one or more products of various kinds. In accordance with the embodiment of the invention illustrated in the attached figures, the centring device 100 is reversibly mountable on a forming unit 110 of a packaging machine.
-
In particular, the forming unit 110 is configured to receive a packaging film F, for example coming from a feeding unit arranged upstream of the forming unit 110 itself, and wherein the feeding unit comprises at least one film reel and film conveying means configured to unwind it and convey it towards an inlet area 10a for the film of the forming unit 110.
-
Specifically, the packaging film F is preformed, so as to make a substantially tubular or annular closed shape.
-
For example, the packaging film F has a shape of a substantially flattened cross-section thereof, so as to make a shape of the oval or oblong type.
-
In other words, the packaging film F is pre-shaped or pre-treated (as mentioned above) in such a way as to have a tubular shape suitable for entering through the inlet area 10a of the forming unit 110, embracing (i.e. wrapping) the guide body 11 like a ring.
-
As just mentioned, the forming unit 110 has an inlet area 10a for the packaging film F configured to receive the film, and an outlet area 10b for the film itself, opposite to the inlet area 10a, configured to discharge the formed packaging film downstream (for example towards one or more heat-sealing units with which the packaging machine is equipped).
-
The forming unit 110 further comprises a guide body 11 having an elongated shape, extending along a sliding axis Y-Y of the packaging film F between the inlet area 10a and the outlet area 10b.
-
The guide body 11 is configured to convey the film itself from the inlet area 10a towards the outlet area 10b of the forming unit 110.
-
Preferably, the guide body 11 has a substantially flattened planar shape, in particular conical from the inlet area 10a towards the outlet area 10b; and configured to receive restingly (on at least one of its faces) the packaging film F during its sliding between the the inlet and outlet areas 10a, 10b. Preferably, the inlet and outlet areas 10a, 10b of the packaging film F are aligned along the sliding axis Y-Y.
-
In accordance with the embodiment illustrated in the attached figures, the centring device 100 for centring a packaging film F for a forming unit 110 comprises a support structure 20 reversibly connectable to the forming unit 110 at the inlet area 10a for the packaging film F.
-
More specifically, the support structure 20 comprises metal plates 20, in particular at least two metal plates 20a, 20b, mechanically coupled to each other, preferably by a connection of the permanent type, for example by welding.
-
As illustrated in detail in figure 2, the the two metal plates 20a, 20b are arranged connected to each other at ninety degrees, so as to make a bracket for anchoring the centring device 100 to the forming unit 110 (see figures 1 and 2).
-
According to one aspect of the invention, the centring device 100 is mounted cantilevered on the forming unit 110 (see figures 1 and 2) at the inlet area 10a of the packaging film.
-
Preferably, the connection between centring device 100 and forming unit 110 is made by means of threaded elements, for example screws, nuts, washers and the like, so as to allow a disassembly thereof.
-
According to the embodiment of the invention, the centring device 100 further comprises centring means 30 connected to the support structure 20 and movable between a rest configuration in which the centring means 30 are proximal to the support structure 20 (i.e. they are located at a distance close to the support structure 20), and an active configuration in which the centring means 30 are distal with respect to the support structure 20 (i.e. they are located at an increased distance with respect to the distance in which they are located in the rest configuration) for compressing the packaging film F against the guide body 11 of the forming unit 110.
-
In other words, the rest configuration corresponds to a position in which the centring means 30 are inactive (i.e. a static condition of the centring means 30), while the active configuration corresponds to a working position (i.e. a dynamic condition of the centring means 30) in which the centring means 30 are in contact with the packaging film F by pressing it against a surface of the guide body 11, and wherein the centring means 30 are selectively activatable only under conditions of the film F skidding with respect to the sliding axis Y-Y, remaining distal from the film itself during its movement along the sliding axis Y-Y.
-
In other words, the centring means 30 have an intermittent operation, i.e. it is activated only under conditions of the film skidding with respect to a predefined direction thereof (i.e. aligned to the sliding axis Y-Y).
-
In particular, as introduced in detail below, a first lever 31 or a second lever 32 or both are selectively activated.
-
The centring device 100 further comprises actuation means 40 connected to the centring means 30 and configured to drive them between the the rest configuration and the active configuration.
-
The actuation means 40 and the centring means 30 will be described in greater detail below.
-
In general, the actuation means 40 are configured to selectively activate at least one of the centring means 30 from the rest configuration to the active configuration, to modify a friction value between the packaging film F and the centring means 30 themselves, so as to align the packaging film F in accordance with a predefined sliding axis Y-Y thereof.
-
In other words, in the case of the packaging film F skidding along a direction transverse to the sliding axis Y-Y such as to produce a deviation of the advancement direction of the film with respect to an advancement direction thereof substantially parallel to the sliding axis Y-Y, the centring means 30 selectively act on the packaging film F during an advancement motion thereof along the sliding axis Y-Y, so as to modify a value of a friction force between the film and the centring means 30 themselves.
-
Advantageously, the centring device 100 allows to automatically return the advancement direction of the packaging film F along an advancement direction parallel and aligned with the the sliding axis Y-Y, and corresponding to a predefined direction of sliding of the film set by the guide body 110.
-
In accordance with the embodiment illustrated in the attached figures, the centring means 30 are rotatably connected to the support structure 20 and configured to perform an oscillating movement between the rest configuration and the active configuration.
-
In other words, the centring means 30 rotate around a respective centre of rotation 35a, 35b (as described in more detail below) between the the rest and active configuration.
-
Still in other words, the centring means 30 perform a tilting movement, that is, completely similar to that of a rocker.
-
In accordance with one embodiment of the invention not illustrated in the attached figures, the movement of the centring means 30 can be of the translational linear type, for example made by means of any linear movement mechanism well known to a person skilled in the art and therefore not further described.
-
In accordance with the embodiment illustrated in detail in figures 2 and 4A-C, the centring means 30 comprise a pair of levers 31, 32 in use side by side and arranged astride the sliding axis Y-Y.
-
In other words, as illustrated in figures 3 and 4C, a first lever 31 is arranged on one side with respect to the sliding axis Y-Y, while a second lever 32 is arranged on the opposite side with respect to the first lever 31, and facing the latter.
-
Preferably, the levers 31, 32 are symmetrically spaced with respect to the sliding axis Y-Y and opposite each other.
-
More in detail, according to an aspect of the invention, the pair of levers 31, 32 comprises a first lever 31 extending between a first end 31a in which a first idle roller 33a is rotatably mounted and a second end 31b connected to the actuation means 40.
-
The pair of levers further comprises a second lever 32 extending between a third end 32a in which a second idle roller 33b is rotatably mounted and a fourth end 32b connected to the actuation means 40.
-
Preferably, as mentioned above, the first lever 31 oscillates with respect to its own centre of rotation 35a arranged in an intermediate position between the first and third ends 31a, 32a; while the second lever 32 oscillates with respect to its own centre of rotation 35b arranged in an intermediate position between the second and fourth ends 31b, 32b.
-
Preferably, the first and second levers 31, 32 are substantially identical between them.
-
Preferably, the first and second idle rollers 33a, 33b are substantially identical between them.
-
According to one aspect of the invention, in particular illustrated in figures 4B-4C, the first and second levers 31, 32 are arranged inclined to each other with respect to the sliding axis Y-Y of the packaging film F with the second and fourth ends 31b, 32b at a distance less than a distance between the first and third ends 31a, 32a.
-
In other words, in accordance with a top plan view (see figure 4C) the first and second levers 31, 32 are arranged in such a way as to realize a conical or wedge-shaped profile.
-
Advantageously, the first and second rollers 33a, 33b press the film in an outer portion thereof with respect to the sliding axis Y-Y, and this pressing contact generates a deviation of the film such as to bring it back centred and aligned with the the sliding axis Y-Y.
-
According to one aspect of the invention, the first and second idle rollers 33a, 33b respectively have a rubberized outer surface thereof.
-
In other words, the outer surface of each idle roller 33a, 33b is deformable or yieldable.
-
Preferably, the outer surface of each idle roller 33a, 33b is covered with a polymeric material, for example natural or synthetic rubber.
-
Advantageously, this rubberized outer surface allows each idle roller 33a, 33b to act on the packaging film F without damaging it, and to exert in contact with the film a value of a friction force such as to deviate the advancement motion of the film.
-
According to one aspect of the invention, the actuation means 40 comprise a pair of cylinders 41, 42 each connected respectively to the first and second levers 31, 32.
-
More in detail, the pair of cylinders comprises a first cylinder 41 and a second cylinder 42, preferably substantially identical between them, and arranged mounted, on the centring device 100, along a working direction transverse, preferably orthogonal, to the sliding axis Y-Y (see figure 4A). In other words, as illustrated in the attached figures, the first and second cylinders 41, 42 are oriented and act along a direction substantially orthogonal to the movement direction of the packaging film F.
-
According to one aspect of the invention, the first and second cylinders 41, 42 respectively comprise their own movable end configured to be rotatably connected respectively to the second and fourth ends 31b, 32b of the first and second levers 31, 32.
-
The first and second cylinders 41, 42 further comprise respectively a fixed end, opposite the respective movable end, and configured to be rotatably connected to the support structure 20.
-
The pair of cylinders 41, 42 preferably comprises cylinders of the pneumatic type.
-
In accordance with one embodiment of the invention not illustrated in the attached figures, the actuation means 40 may comprise electric, hydraulic or other cylinders, well known to a person skilled in the art and therefore not further described.
-
In accordance with one embodiment of the invention, the centring device 100 comprises a sensor 50 (schematically illustrated in the attached figures) arranged parallel to the sliding axis Y-Y and configured to detect a deviation of the packaging film F with respect to the predefined sliding axis Y-Y.
-
In other words, the sensor 50 is mounted on the forming unit 110 at an intermediate position between the inlet area 10a and the outlet area 10b of the packaging film F, parallel to the sliding axis Y-Y. In particular, the sensor 50 is configured to detect a misalignment (or deviation or offsetting) of a position of the packaging film F with respect to a predefined position thereof substantially parallel and aligned with the sliding axis Y-Y during a movement of the film itself along the guide body 11.
-
In addition, the sensor 50 is configured to translate this deviation value into an electrical signal to be transmitted to an electronic control unit (introduced and described in more detail below).
-
Preferably, the sensor 50 is a photocell.
-
In accordance with one embodiment of the invention, the centring device 100 further comprises an electronic control unit connected to the the sensor 50 and to the actuation means 40, configured to receive the the deviation (or misalignment) signal from the sensor 50 and send a centring signal to the actuation means 40 to selectively move only one of the centring means 40 in the active configuration.
-
As illustrated in the attached figures 1-4C, the operation of the invention is as follows.
-
The forming unit 110 comprises a guide body 11 extending along the sliding axis Y-Y and is configured to receive the packaging film F; the latter comes from a reel (not illustrated) placed upstream of the forming unit 110, and is preformed so as to make a substantially tubular shape, in particular flattened to wrap the guide body 11 during a sliding thereof along the sliding axis Y-Y, so as to form a plurality of packages.
-
If the direction along which the packaging film F slides deviates or is offset with respect to the sliding axis Y-Y, this deviation or offsetting is detected by the sensor 50.
-
In fact, this sensor 50 transduces a film deviation or offsetting value into an electrical signal to be sent to the electronic control unit.
-
The latter receives the electrical signal from the sensor 50, processes it and transmits a centring signal (proportional to the the electrical signal) selectively to control elements, for example pneumatic valves for regulating an air flow, connected respectively to the first and second cylinders 41, 42. More in detail, such pneumatic valves (not illustrated in the attached figures) intercept and regulate an air flow coming for example from a centralized compressed air system, towards each first and second cylinder 41, 42 to actuate the movement thereof (i.e. to extend the stem of the selected cylinder along an upward vertical direction - see figure 4A).
-
The activation of the first and/or second cylinders 41, 42 causes the movement respectively of the first and/or second levers 31, 32 and therefore correspondingly of the first and/or second idle rollers 33a, 33b.
-
In this way, the first and/or second idle rollers 33a, 33b selectively compress, against the guide body 11 of the forming unit 110, respective lateral portions (i.e. portions arranged respectively on one side and on the opposite side of the film with respect to the sliding axis Y-Y) of the packaging film 110 during a sliding thereof along the sliding axis Y-Y.
-
In this way, the the pressing contacts of the first and/or second rollers 33a, 33b produce a friction force on the packaging film F such as to vary its movement direction and re-align the film itself along the sliding axis Y-Y.
-
In particular, the first and/or second cylinders 41, 42 are selectively driven as a function of a direction along which the packaging film F deviates with respect to the sliding axis Y-Y.
-
Specifically, one of the first and second cylinders 41, 42 that is in a position opposite to a deviation or offsetting direction of the packaging film F with respect to the sliding axis Y-Y is activated.
-
A forming unit 110 for an automatic packaging machine is also an object of the present invention, of which the same numerical references will be maintained for simplicity of exposure.
-
Specifically, the forming unit 110 comprises a support frame 10, preferably made of metallic material, and movable in a plane parallel to the ground so as to be associable with a packaging machine.
-
The forming unit 110 further comprises an elongated guide body 11, connected to the support frame 10, and extending along a sliding axis Y-Y of a packaging film F.
-
The forming unit 110 further comprises a centring device 100 having one or more of the above characteristics.