WO2024201359A1 - Unwinding apparatus for wrapping machine and wrapping method - Google Patents

Abstract

An unwinding apparatus (1) associable with a wrapping machine (100) in order to deliver a film or strip (50) made of plastic and/or paper material with which to wrap a load (200), comprises a supporting frame (2) for rotatably supporting a reel (60) of film or strip (50), roller means (10) for unwinding the film or strip (50) from the reel (60) and guiding it out towards the unwinding apparatus (1) and the load (200), blowing means (20) arranged to deliver at least one air blow (F) towards the roller means (10) so as to keep the film or strip (50) outstretched, wound on and adhering to the roller means (10); sensor means (18) for detecting a pulling force acting on the film or strip (50) and control means (19) connected to the sensor means (18) and configured to activate the blowing means (20) and deliver the air blow (F) towards the roller means (10) when the pulling force of the film is lower than a predefined minimum value.

Description

Unwinding apparatus for wrapping machine and wrapping method

The invention relates to unwinding apparatuses associable with wrapping machines for delivering a film or strip of plastic and/or paper material with which to wrap a load and in particular it relates to an unwinding apparatus that can be installed on a fixed or self- propelled wrapping machine. The invention further relates to a method for wrapping a load with a film or a strip of plastic and/or paper material.

It is known in the packaging sector to wrap with a plastic film, in particular of the cold extensible type, or with a strip of paper material, a load formed by a single product or by a plurality of products grouped and/or stacked on a pallet, or a palletised load.

The known wrapping machines comprise at least an unwinding apparatus which is movable parallel and/or around a wrapping axis and which supports a reel from which the film or strip is unwound to be wound around the load so as to form a series of strips or bands generally having a helical trend, due to the combination of the relative linear and rotational movements between the unwinding apparatus and the load.

In wrapping machines provided with a rotating table for supporting the load, during the wrapping cycle the latter is rotated around a vertical wrapping axis, while the unwinding apparatus is moved parallel to the wrapping axis with a reciprocating motion along a fixed column of the wrapping machine.

In wrapping machines with a horizontal rotating ring or rotating arm, the load remains static during the wrapping, while the unwinding apparatus is moved with respect to the latter both in rotation around a vertical wrapping axis and in translation parallel to the latter. For this purpose, the unwinding apparatus is fixed to a ring structure or to an arm, both of which are rotatably supported so as to rotate around the load by a frame of a vertically movable machine.

In wrapping machines with a vertical rotating ring the load is moved horizontally by means of the ring structure, while the unwinding apparatus fixed to the ring structure is rotated around a horizontal axis.

In self-propelled wrapping machines, also called wrapping robots, the unwinding apparatus is movable with a reciprocating motion along a column fixed to a self-propelled cart or carriage generally provided with at least one motorized wheel and a guiding device comprising one or more steering wheels that are operated by a steering. The steering can be operated via a guiding bar shaft by an operator to manually drive the machine in a manoeuvring configuration or by a feeler element capable of following the external profile of the load in a working configuration, in which the self-propelled machine turns autonomously around the load to wrap it with the film.

The unwinding apparatus is generally provided with a plurality of guiding or return rollers to divert the film or strip unwound by the reel out of the apparatus and towards the load during the wrapping cycle.

In particular, in the case of wrapping with a film made of cold extensible plastic material, the unwinding apparatus may comprise, in addition to the guiding rollers, a pair of prestretching rollers arranged to unwind the film from the reel and then stretch or elongate it. By appropriately adjusting the difference between the rotation speeds of the pre-stretching rollers, it is in fact possible to elongate or pre-stretch the film exiting the unwinding apparatus by a defined amount.

During wrapping, the film is wound with a specific and determined pulling force or wrapping tension or "pull" around the load so as to guarantee its stability and compactness, in particular when said load is formed by a plurality of overlapping products. The pulling force is achieved by appropriately selecting the operating parameters of the wrapping machine including relative rotation speed between load and unwinding apparatus, dispensing or exiting speed of the film coming out from the unwinding apparatus, elongation or prestretching percentage of the film, if provided.

The pulling force of the film exiting the unwinding apparatus also ensures that the film is correctly positioned and outstretched on the guiding rollers and pre-stretching rollers.

A disadvantage of the known unwinding apparatuses is that if the wrapping force of the film is small or substantially zero (for example in the case of unstable or light products on which the film must be applied without generating stresses and in a gradual and progressive manner or in an initial step of the wrapping cycle in which a film initial end is associated with the load to be wound) the film can slide by gravity along the rollers, in particular along the guiding rollers and the pre-stretching roller that are closest to the exit of the unwinding apparatus. Actually, if the pulling force acting on the film decreases also decreases its adherence to the external surfaces of the pre-stretching and guiding rollers. The film or strip sliding downward thus tends to form folds and ripples and/or to shrink transversely, presenting unwanted corrugated and/or rolled longitudinal sections. In some cases, the film or strip, in particular if it is made of plastic material, may get stuck and jammed around the base of the rollers.

To try to overcome this disadvantage, guiding and pre-stretching rollers having a large diameter are used in order to increase the wrapping and contact surface of the film around the rollers and therefore its adherence thereto. This solution, however, in addition to making the unwinding apparatus more cumbersome and expensive, does not always prevent the film from descending even only partially along the rollers.

WO 2022/088369 discloses an apparatus for automatic packaging of reel material comprising a loading table, an unloading table disposed downstream of the loading table, a device for pulling the reel material disposed between the loading table and the unloading table, a first distance measuring unit and a second distance measuring unit disposed respectively at the left end and the right end of the reel material guiding device, two paper cover feeding devices disposed respectively on a left side and a right side of the pulling device for the reel material, and a beam frame disposed fixed on the unloading table. The apparatus further comprises a wrapping head for unwinding a packaging film disposed on the beam frame, an operating module for moving the wrapping head, and a pushing device for pushing the reel material once packaged on the unloading table.

WO 2022/119573 discloses an apparatus and a method for wrapping extensible film around a palletised load using feedback of the film tension measured from a load cell. The load cell measures the film tension to determine a film dispensing speed. The film tension values are used to determine when an out-of-bounds condition occurs, i.e. when film breakage has occurred or when a possible film breakage is about to occur or when the film has been cut at the end of a wrapping cycle. To prevent entanglement of the free end of the film following a break, grippers are provided that hook the film in order to control its tail. The tail of the broken film can then be quickly and reliably reattached to the rotating load at a desired position.

An object of the invention is to improve the known unwinding apparatuses associable with wrapping machines and the methods for wrapping a load with a film or strip of plastic and/or paper material.

Another object is to provide an unwinding apparatus and a wrapping method that allow the film or strip to be kept correctly positioned, outstretched and wound on the guiding and/or pre-stretching rollers, preventing the film or strip from descending and/or shrinking and/or partially or completely rolling up, even in the event of a pulling or wrapping force acting on the film or strip having a little or substantially zero value.

A further object is to provide an unwinding apparatus having simple and economical construction and a precise and reliable operation.

In a first aspect of the invention an unwinding apparatus according to claim 1 is provided.

In a second aspect of the invention, a method for wrapping a load according to claim 10 is provided.

The invention can be better understood and implemented with reference to the attached drawings which illustrate exemplary and non-limiting embodiments thereof, wherein: figure 1 is a perspective view of the unwinding apparatus of the invention associated with a rotating table wrapping machine; figure 2 is an enlarged detail of figure 1 illustrating the unwinding apparatus in an operating step; figure 3 is another perspective view of the unwinding apparatus of figure 2; figure 4 is a perspective view of a variant of the unwinding apparatus of the invention associated with the wrapping machine, partially shown; figure 5 is a front view of the unwinding apparatus of figure 4 associated with the wrapping machine, partially shown.

With reference to figures 1 to 3, the unwinding apparatus 1 of the invention is illustrated, associable to a wrapping machine 100 for delivering a film or strip or band 50 made of plastic and/or paper material with which to wrap a load 200, which is for example formed by a single product or by a plurality of products grouped and arranged on a pallet or bed.

In the example illustrated in the figures, the unwinding apparatus 1 is mounted on a wrapping machine 100 of the rotating table type and comprising a table or platform 102 adapted to support the load 200 and rotatable about a wrapping axis W, in particular substantially vertical. The wrapping machine 100 also comprises a column 101 parallel to the wrapping axis W and adapted to slidably support the unwinding apparatus 1. The latter is fixed to a carriage that is movable with reciprocating motion along the column 101.

The unwinding apparatus 1 of the invention includes a supporting frame 2 for rotatably supporting a reel 60 of film or strip 50 and roller means 10 arranged at least to unwind the film 50 from the reel 60 and guide the film or strip out towards the load 200 during wrapping. In the embodiment illustrated in figures 1 to 3, the roller means 10 comprise a plurality of guiding rollers 13 and a pair of pre-stretching rollers 11, 12 adapted to unwind from the reel 60 and pre-stretch or elongate the film 50 by a defined percentage or amount.

Alternatively, roller means 10 may only comprise guiding rollers 13 suitable for unwinding and forwarding, directing the film or strip 50 unwound from the reel 60 out towards the load 200.

Blowing means 20 are therefore configured and oriented to deliver one or more air blows F towards said guiding rollers 13 and pre- stretching rollers 11, 12, and in particular on the prestretching roller 12 that is positioned downstream, with reference to an unwinding direction A of the film 50, i.e. the pre- stretching roller 12 so-called fast roller, rotatable with a rotation speed greater than the one of the pre-stretching roller 11, so-called slow roller, positioned upstream with reference to the unwinding direction A.

Blowing means 20 comprise one or more supplying nozzles 21 fixed to the supporting frame 2 and configured to emit respective air blows or jets F, in particular blade-shaped blows or jets. In the illustrated embodiment, the blowing means 20 comprise two supplying nozzles 21 connected by respective flexible ducts 22 to a source of pressurised air of the wrapping machine 100.

Each supplying nozzle 21, of known type and not described in detail, is fixed in an adjustable manner to the supporting frame 2 so that the air blow F emitted thereby is able to optimally hit the pre-stretching rollers 11, 12 and the guiding rollers 13 and keep the film 50 that is wrapped around said rollers in the right position, completely and correctly outstretched and wound, while preventing the film from possibly descending due to gravity.

The unwinding apparatus 1 also comprises sensor means 18 adapted to detect a pulling force, so-called "pull", acting on the film 50, in particular when dispensed by the roller means 10 during the wrapping cycle. The sensor means 18, of known type and not described in detail, are for example associated with one of the pre-stretching rollers 11, 12 or with one of the guiding rollers 13.

The unwinding apparatus 1 can also comprise control means 19 connected to the sensor means 18 and configured to activate the blowing means 10 and deliver the air blow F towards the roller means 10 when the pulling force of the film is lower than a predefined minimum value.

The control means 19 can be included in the main control unit of the wrapping machine 100 on which the unwinding apparatus 1 is mounted.

Figures 4 and 5 illustrate a variant of the unwinding apparatus 1 of the invention which differs from the embodiment above described and illustrated in figures 1 to 3 in that it comprises further blowing means 30 and in that the roller means 10 comprise a plurality of guiding rollers 13 and an unwinding roller 14, adapted to unwind and/or control the unwinding of the film 50 from the reel 60.

The unwinding roller 14 is, for example, controllable in rotation speed, e.g. by means of a brake or a motor, so as to regulate the pulling or wrapping force, otherwise known as "pull", of the film or strip 50 during the wrapping cycle, in particular so as to keep the value of said pulling force within a predefined range in order to avoid, on the one hand, film breakage, on the other hand, a too loose wrapping of the load. The further blowing means 30 are configured to deliver at least one further air blow Fl towards the film or strip 50 exiting the roller means 10 and directed towards the load, in particular a further air blow Fl parallel to the unwinding direction A of the film or strip 50 along which the film or strip 50 exiting the unwinding apparatus 1 is moved.

The further blowing means 30 comprise one or more further supplying nozzles 31 fixed to the supporting frame 2 and arranged to emit respective further air blows Fl on the film or strip 50 while exiting.

In the embodiment illustrated in figures 4 and 5, the further blowing means 30 comprise a pair of further supplying nozzles 31 fixed to the supporting frame 2, in particular in an adjustable manner, and opposite to each other and facing to emit respective further air blows or jets Fl on opposite faces of the film or strip 50 exiting from the roller means 10 so as to push said film along the unwinding direction A towards the load 200 arranged in a flag-like manner and substantially vertical. In particular, in an initial step of the wrapping cycle the further air blows Fl push an initial end or head of the film towards the load 200, for example against a side wall of the latter or on an abutment element of a load supporting plane 200 so as to block said film end and allow it to be covered and pressed by one or more bands of film subsequently wound around the load.

The operation of the unwinding apparatus 1 of the invention, associated with a wrapping machine 100, for example the rotating table wrapping machine of Figure 1, provides for the activation of roller means 10 to unwind from the reel 60 and possibly to pre-stretch the film 50 and the activation of blowing means 20 to keep the film 50 correctly positioned and outstretched and wound on the guiding rollers 13 and/or pre- stretching rollers 11, 12 of roller means 10, preventing the film from descending and partially or completely shrinking and/or rolling up. More precisely, the air blows F emitted by the supplying nozzles 21 of blowing means 20 hit and push the film 50 on the pre-stretching rollers 11, 12 and on the guiding rollers 13 keeping the film correctly positioned and wound around said rollers.

In particular, in an initial step of a wrapping cycle of the load 200, in which the film 50 is for example blown towards the load 200 by the further blowing means 30 - and therefore is not stretched, i.e. is not subject to any pulling force, and would tend to slide under the gravity effect downwards along the guiding and pre-stretching rollers - the air blows F emitted by the supplying nozzles 21 keep the film 50 correctly wound and adhering to the fast prestretching roller 12 and also correctly wound and adhering around the slow pre-stretching roller 11 and the guiding rollers 13.

The blowing means 20 can be kept active throughout the wrapping cycle of the load 200 to ensure the correct positioning of the film 50 on the roller means 10.

Alternatively, the blowing means 20 can be activated by the control means 19 to emit the air blows F during the wrapping cycle of the load 200 only when the sensor means 18 detect a pulling force acting on the film 50 lower than a predefined minimum value, i.e. a value of the traction or pulling force not sufficient to prevent the movement of the film 50 due to the gravity effect downwards along the guiding rollers 13 and pre-stretching rollers 11, 12 with consequent undesirable formation of folds, rolling in the film.

It should be noted that the unwinding apparatus 1 of the invention can also be mounted on a wrapping machine 100 with horizontal rotating ring or with rotating arm in which the load 200 remains stationary during wrapping while the unwinding apparatus 1 is moved either in rotation about a vertical wrapping axis and in translation parallel to the wrapping axis. The unwinding apparatus 1 can be fixed to a ring structure or to an arm rotatably supported by a machine frame and so as to rotate around the load.

The unwinding apparatus 1 of the invention can also be mounted on a wrapping machine with vertical rotating ring in which the load is moved horizontally through the ring structure, while the unwinding apparatus fixed to the ring structure is rotated about a horizontal axis. Finally, the unwinding apparatus 1 can be mounted on a self-propelled wrapping machine, or a self-propelled wrapping robot, in particular slidably coupled to a vertical upright fixed to a self-propelled carriage or cart provided with motorized traction wheels and a guiding device that comprises one or more steerable wheels, operated by a steering.

The method according to the invention for wrapping a load 200 with a film or strip 50 made of plastic and/or paper material by means of the wrapping machine 100 provided with the unwinding apparatus 1 of the invention comprises the steps of: unwinding the film 50 from the reel 60 and guiding the film out of the unwinding apparatus 1 by operating the roller means 10 thereof; activating the blowing means 20 to generate at least one air blow F towards the roller means 10 so as to keep the film or strip 50 outstretched, wound on and adhering to the roller means 10; wrapping the load 200 with the film or strip 50 dispensed by the unwinding apparatus 1; detecting by the sensor means 18 a pulling or wrapping force acting on the film or strip 50 when dispensed by the roller means 10 and activating the blowing means 20 to generate at least one air blow F on the roller means 10 when the pulling force is lower than a predefined minimum value. The method further comprises, before wrapping the load, associating an initial end of the film or strip 50 to the load 200, the blowing means 20 being activated during said associating. Thanks to the unwinding apparatus 1 of the invention associable with a fixed or self- propelled wrapping machine and to the wrapping method of the invention, it is therefore possible to wrap a load 200 with a film or strip 50 made of plastic and/or paper material in a complete and regular manner, in particular avoiding that fold, shrinkages, rolling may form in the film 50 during unwinding due to its movement along the pre-stretching rollers 11, 12 and guiding rollers 13 of roller means 10, as a result of small or substantially zero values of the pulling or wrapping force acting on the film 50. More precisely, even in the absence of an adequate pulling force that keeps the film correctly wound and adhering to the prestretching and guiding rollers, the air blows F generated by the blowing means 20 allow the film to be kept positioned, outstretched and wound on the aforementioned guiding rollers 13 and/or pre-stretching rollers 11, 12, preventing it from descending and/or partially or completely shrinking and/or rolling up.

Claims

1. Unwinding apparatus (1) associable with a wrapping machine (100) in order to deliver a film or strip (50) made of plastic and/or paper material with which to wrap a load (200), comprising a supporting frame (2) for rotatably supporting a reel (60) of said film or strip (50); roller means (10) at least for unwinding said film or strip (50) from said reel (60) and guiding it out of said unwinding apparatus (1) and towards said load (200); blowing means (20) arranged to generate at least one air blow (F) towards said roller means (10) so as to keep said film or strip (50) outstretched, wound on and adhering to the roller means (10); characterized in that it comprises sensor means (18) for detecting a pulling force acting on said film or strip (50) and control means (19) connected to said sensor means (18) and configured to activate said blowing means (20) and deliver said air blow (F) towards said roller means (10) when said pulling force is lower than a predefined minimum value.

2. Unwinding apparatus (1) according to claim 1, wherein said roller means (10) comprise a plurality of guiding rollers (13) arranged to unwind and direct the exiting film or strip (50) towards said load (200), said blowing means (20) being configured and oriented to deliver said at least one air blow (F) towards said guiding rollers (13).

3. Unwinding apparatus (1) according to claim 1 or 2, wherein said roller means (10) further comprise a pair of pre- stretching rollers (11, 12) suitable to unwind from the reel (60) and pre-stretch the film or strip (50), said blowing means (20) being configured and oriented to deliver said at least one air blow (F) also towards said pre- stretching rollers (H, 12).

4. Unwinding apparatus (1) according to any preceding claim, wherein said roller means (10) further comprise at least one unwinding roller (14) suitable to unwind and/or control unwinding of said film or strip (50) from the reel (60), said blowing means (20) being configured and oriented to deliver said at least one air blow (F) also towards said at least one unwinding roller (14).

5. Unwinding apparatus (1) according to any preceding claim, wherein said blowing means (20) comprise at least one supplying nozzle (21) fixed to said supporting frame (2) and arranged to emit at least one air blow (F), in particular a blade-shaped air blow.

6. Unwinding apparatus (1) according to any preceding claim, wherein said blowing means (20) comprise a plurality of supplying nozzles (21) fixed to said supporting frame (2) and arranged to emit respective air blows (F), in particular blade-shaped air blows.

7. Unwinding apparatus (1) according to claim 5 or 6, wherein said supplying nozzle (21) is fixed in an adjustable manner to said supporting frame (2).

8. Unwinding apparatus (1) according to any preceding claim, comprising further blowing means (30) arranged to deliver at least one further air blow (Fl) towards said film or strip (50) exiting from said roller means (10) and directed towards said load (200), in particular said further air blow (Fl) being parallel to an unwinding direction (A) along which said film or strip (50) moves while exiting the unwinding apparatus (1).

9. Unwinding apparatus (1) according to claim 8, wherein said further blowing means (30) comprise at least one further supplying nozzle (31) fixed to said supporting frame (2), in particular in an adjustable manner, and arranged to emit at least one further air blow (Fl) on said film or strip (50) exiting the unwinding apparatus (1) .

10. Method for wrapping a load (200) with a film or strip (50) made of plastic and/or paper material by means of a wrapping machine (100) provided with an unwinding apparatus (1) according to any preceding claim, comprising: unwinding said film or strip (50) from a reel (60) and guiding the film or strip out of the unwinding apparatus (1) by activating the roller means (10) thereof; activating blowing means (20) to generate at least one air blow (F) towards said roller means (10) so as to keep said film or strip (50) outstretched, wound on and adhering to the roller means (10); wrapping said load (200) with said film or strip (50) dispensed by said unwinding apparatus (1); detecting by means of sensor means (18) a pulling force acting on said film or strip (50) and activating said blowing means (20) to generate at least one air blow (F) on said roller means (10) when said pulling force is lower than a predefined minimum value

11. The method according to claim 10, comprising before said wrapping, associating an initial edge of film or strip (50) to said load (200), said blowing means (20) being activated during said associating.

12. Wrapping machine (100) for wrapping a load (200) with a film or strip (50) made of plastic and/or paper material comprising at least one unwinding apparatus (1) according to any of claims 1 to 9.