The invention concerns unwinding apparatuses associable with wrapping machines for dispensing a film of plastic material with which to wrap a load consisting of a product or of a plurality of products arranged on a pallet. In particular, the invention relates to an unwinding apparatus that can be installed on a wrapping machine that is movable or so- called self-propelled.

Self-propelled wrapping machines, also referred to as self-propelled wrapping robots, are machines that are generally used to wrap loads having variable shapes and sizes and in small- scale productions, typically in environments or production premises in which fixed or static wrapping machines cannot be used.

Self-propelled wrapping machines include a carriage provided with at least one motorized rear wheel and a front guiding device comprising a pair of steering wheels, guided by a steering wheel. The steering wheel may be driven via a guiding bar 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 automatically rotates around the load to wrap it with the film.

The carriage supports a vertical column or upright along which an unwinding or dispensing apparatus is movable which houses a reel of plastic film and a plurality of rollers for unwinding and pre- stretching the film. More precisely, the unwinding apparatus is generally provided with a pair of pre-stretching rollers arranged to unwind the film from the reel and pre-stretch or elongate it, and one or more return rollers to deviate the film towards the load. The combination of the reciprocating linear movement of the unwinding apparatus along the vertical upright and of the rotation of the self-propelled machine around the load allows the film to be wrapped around the latter so as to form a series of intertwined bands or strips with a helical pattern. The plastic film is wound in such a way as to completely wrap the load on all its sides.

For stabilizing the load when it is placed on a pallet it is also necessary to wrap the film around a base of the load itself and an upper portion of the pallet. If this is not done, the load, especially if it is made up of a group of separate products, could dangerously move with respect to the pallet during wrapping and/or subsequent transport.

To ensure adequate tension to the film and to ensure greater resistance to the tensile forces caused, for example, by displacements or movements of the load, it is necessary to narrow transversely, completely or partially, the film so as to reduce an amplitude or width of the band or strip and to realize a narrow band or a rolled up portion that forms a kind of rope or cord to be wrapped tightly around the load and the pallet. This narrow or rolled up band obtained by progressively pushing and compressing a longitudinal edge of the film transversely to the unwinding direction (so-called film creasing), allows, in fact, to obtain a greater wrapping force and a lower elastic elongation compared to the film with a full width band. The film gathered or rolled up into a rope is also used to better stabilize and reinforce the parts of the load that are more unstable.

To this end, various devices or mechanisms are known adapted to narrow the film transversely, so-called band tightening, which are however only used for encumbrance and space reasons on static wrapping machines, for example rotating platform machines, or ring or rotating arm machines. Moreover, such film narrowing devices do not make it possible to precisely control the extent of the transverse narrowing or creasing made on the output film during the operating cycle.

The known devices also allow to act selectively only on one of the two longitudinal edges, lower or upper, of the film and to operate on the other edge; these devices require changes and adjustments for which the intervention of specialized personnel and the shutdown of the wrapping machine and consequently the production stop are necessary.

EP 3070003 describes an unwinding apparatus for a self-propelled wrapping machine comprising frame means for supporting a reel of film, roller means for unwinding the film and a movable folding element for abutting a first longitudinal edge of the film and pushing it towards a second longitudinal edge so as to reduce a band width of the film. The apparatus also comprises moving means controlled by a control unit and arranged to move the folding element in a controlled manner along a narrowing trajectory of the film. Sensors are provided for continuously detecting and measuring a displacement of the folding element and for sending a relative signal to the control unit.

An object of the invention is to improve the known unwinding apparatuses associable with self-propelled wrapping machines for wrapping a load with a film of extensible plastic material.

Another object is to realize an unwinding apparatus for self-propelled wrapping machines that allows to select the longitudinal edge, upper or lower, of the film on which to act to narrow the film, that is to modify a band amplitude or width, in particular to realize a portion gathered or rolled up in the form of a rope on said film.

A further object is to provide an unwinding apparatus for self-propelled wrapping machines that allows the band amplitude or width of the plastic film to be varied in a simple, fast and precise way during its wrapping around the load. Another object is to realize an unwinding apparatus having simple and economical construction and effective and reliable operation.

A further object of the invention is to realize an unwinding apparatus for self-propelled wrapping machines that allows for the easy and rapid replacement of a spent reel of film. These objects and still others are achieved by an unwinding apparatus according to claim 1. The unwinding apparatus according to the invention associable with a self-propelled wrapping machine that is movable around a load to wrap the latter with a film of plastic material, comprises frame means for supporting a reel of film and roller means for unwinding and pre- stretching the film along an unwinding direction.

The unwinding apparatus further includes a folding device comprising a folding element and relative driving means for moving the folding element along a narrowing trajectory transversal to the unwinding direction of the film to abut and narrow the film so as to reduce a band width thereof.

The unwinding apparatus also includes a containment casing connected to the frame means and defining an internal compartment suitable for containing the roller means and the folding device and provided with an access door movable between an open position and a closed position to allow and prevent access to the internal compartment, respectively. The folding device is advantageously fixed to an inner wall of the door.

The driving means are configured to selectively arrange the folding element in a first position and to move it along the narrowing trajectory so as to abut a first longitudinal edge of the film and push it towards a second longitudinal edge of the film or to arrange the folding element in a second position and to move it along the narrowing trajectory so as to abut the second longitudinal edge of the film and push it towards the first longitudinal edge of the film.

Advantageously, the unwinding apparatus according to the invention modifies the amplitude of the band of films with which to wrap loads.

Thanks to the folding device it is in fact possible to realize a portion of folded or rolled up or creased film to wrap the load. In addition, the possibility of rolling the film starting from a first longitudinal edge or from a second longitudinal edge gives greater operational versatility to the apparatus.

The invention can be better understood and implemented with reference to the attached drawings which illustrate some exemplifying and non-limiting embodiments thereof, in which: figure 1 is a perspective view of the unwinding apparatus of the invention with an access door in the closed position; figure 2 is a front view of the unwinding apparatus of figure 1; figure 3 is an enlarged section along line III-III of figure 2; figure 4 is an enlarged section along line IV-IV of figure 2 with the access door in the open position; figure 5 is an enlarged front view of the unwinding apparatus of the invention with the access door in the open position; figure 6 is an enlarged section along line VI- VI of figure 5 with the access door in the closed position; figure 7 is an enlarged front view of a folding device of the unwinding apparatus of the invention arranged to transversely narrow the film with a folding element in a low initial position and, illustrated in a dashed line, in a high initial position; figure 8 is a perspective view of the folding device of figure 7 with the folding element in the high initial position. figure 9 illustrates a perspective view of a self-propelled wrapping machine provided with the unwinding apparatus of figure 1.

With reference to figures 1 to 9, there is illustrated an unwinding apparatus 1 associable with a self-propelled wrapping machine 100 that is movable around a load 200 to wrap the latter with a film 50 of extensible plastic material.

The self-propelled wrapping machine 100, of the known type, substantially comprises a main carriage 101 provided with motorized wheels 102 and a guiding device 103. A vertical upright 105 is fixed to the main carriage 101 and along which the unwinding apparatus 1 object of the invention is slidingly fixed.

The unwinding apparatus 1 comprises frame means 2 supporting a reel 60 of film 50 and roller means 11, 12, 13, 14 for unwinding, pre- stretching and deviating the film 50 along an unwinding direction V. The roller means 11, 12, 13, 14 are driven in rotation around respective longitudinal axes by a motorisation assembly, of a type known and not described in detail.

The self-propelled wrapping machine 100 further comprises a folding device 3 having a folding element 5 and driving means 10. In particular, the driving means 10 move the folding element 5 along a narrowing trajectory R transversal to the unwinding direction V of the film 50 to come into abutment with the latter and therefore push it in such a way as to reduce the amplitude of the film band 50 unwound. More precisely. The folding element 5 moved towards the first or the second longitudinal edge 50a, 50b during the unwinding of the film 50 pushes said longitudinal edge by rolling it up or gathering it into a pleated form so as to narrow the film band 50 unwound or to reduce it so as to form a rope.

The driving means 10 are further configured to selectively arrange the folding element 5 in a first position PI to move it along the narrowing trajectory R so as to abut a first longitudinal edge 50a of the film (e.g. the upper longitudinal edge with reference to figure 5) and push it towards a second longitudinal edge 50b of the film 50 (e.g. the lower longitudinal edge with reference to figure 5). Alternatively, the driving means 10 arrange the folding element 5 in a second position P2 to move it along the aforementioned narrowing trajectory R so as to abut the second longitudinal edge 50b of film 50 and push it towards the first longitudinal edge 50a.

In particular, the driving means 10 comprise a moving system 15 of the lead screw nut type, of the type known and not illustrated and described in detail, driven by a first rotary electric motor 25. The moving system 15 acts on a slide 16 supporting the folding element 5 in order to move it linearly along the narrowing trajectory R. The moving system 15 also comprises a guide 17 adapted to slidingly support the slide 16. The slide 16, therefore, in use, is made to slide along the guide 17 in such a way as to move the folding element 5, for example in a position between the first and the second position PI, P2.

The winding apparatus 1 comprises a containment casing 4 connected to the frame means 2 defining an internal compartment 6 suitable for containing the roller means 11, 12, 13, 14 and the folding device 3. Furthermore, the internal compartment 6 is provided with an access door 7 movable between an open position A and a closed position C, to allow and prevent access to the internal compartment 6, respectively. In particular, the door 7 is rotatably associated with the containment casing 4.

In particular, the folding device 3 is fixed to an inner wall 7a of the door 7. This makes it easier to access the aforementioned folding device 3, for example in case of maintenance, by opening the door 7 into the open position A.

The roller means 11, 12, 13, 14 comprise at least one pair of pre-stretching rollers 11, 12 which unwind from the reel 60 and stretch the film 50 and at least one pair of guiding rollers 13, 14 which direct the film 50 towards the aforementioned pre- stretching rollers 11, 12 and the folding device 3.

According to a preferred embodiment, a portion of film 50 unwound from the reel 60 abuts in the order a first guiding roller 14, a second pre- stretching roller 12, a first pre- stretching roller 11, two second guiding rollers 13, the folding device 3 and a further second guiding roller 13. The first and the second pre- stretching roller 11, 12 rotate with different rotational speeds so as to stretch, or spread by elongation, the film 50 of plastic material during unwinding from the reel 60. The first pre-stretching roller 11 (fast roller) rotates at a speed greater than the rotational speed of the second pre-stretching roller 12 (slow roller).

The reel 60 is mounted on a winder 106 so that it is free to rotate and unwind the film 50 by cooperating with the roller means 11, 12, 13, 14. In particular, a first guiding roller 14 directs the film 50 towards the second pre- stretching roller 12 and the first pre-stretching roller 11. The stretched film 50, at the exit from the pre-stretching rollers 11, 12 is directed by the second guiding rollers 13 towards the load 200.

One of the pre-stretching rollers 11, 12, in particular the second pre-stretching roller 12, and at least one of the second guiding rollers 13, in particular two, are rotatably fixed and supported by the door 7 to facilitate the insertion of the film 50 between the pre- stretching rollers 11, 12 and the second guiding rollers 13 when the same door 7 is arranged in the open position A. Furthermore, this arrangement of the rollers allows easy access to each element of the apparatus 1 especially in case of maintenance activities.

The folding element 5 comprises a respective roller that is free to rotate about a respective axis and is provided with an annular groove 5a adapted to abut and receive either the first longitudinal edge 50a or the second longitudinal edge 50b so as to roll it up or fold it, pleat it and push it towards the opposite longitudinal edge and realize a narrow, creased or rolled up portion of the film 50.

The unwinding apparatus 1 also comprises a control unit 20 connected to the driving means 10 at least to adjust a displacement and/or a movement direction of the folding element 5 along the narrowing trajectory R.

The unwinding apparatus 1 comprises sensor means 21, 22 for detecting at least the first position PI and the second position P2. More precisely, the sensor means 21, 22 comprise a first sensor 21, for example of an optical type, adapted to detect when the folding element 5 is in the first position PI and a second sensor 22, for example of an optical type, adapted to detect when the folding element 5 is in the second position P2. The sensor means 21, 22 are connected to the control unit 20 to send respective signals thereto. In particular, the sensor means 21, 22 allow a better control of the unwinding apparatus 1.

The operation of the unwinding apparatus 1 during a winding cycle, in which the self- propelled wrapping machine 100, on which the unwinding apparatus 1 is installed, rotates around a load 200 to be wound, provides that the film 50 is unwound from the reel 60, pre stretched by the pre- stretching rollers 11, 12 and moved along the unwinding direction V at the exit from the unwinding apparatus 1 towards the load. Before the start of the winding cycle, in an initial adjustment step, the folding element 5 is positioned in the first position PI or in the second position P2 according to the type of winding to be made. More precisely, when the folding element 5 is initially arranged in the first position PI during winding it is able to abut the first longitudinal edge 50a and fold it towards the second longitudinal edge 50b so as to form a narrow band (partial or complete) or an upper crease. Differently, when the folding element 5 is initially arranged in the second position P2 during winding it is able to abut the second longitudinal edge 50b and fold it towards the first longitudinal edge 50a so as to form a narrow band (partial or complete) or a lower crease.

More precisely, in order to narrow the film 50, the driving means 10 move the slide 16, supporting the folding element 5, along the guide 17. The folding element 5 abuts the longitudinal edge of the film and progressively folds the latter along the narrowing direction R so as to realize a narrow, pleated or rolled up, partial or complete, band.

When the reel 60 50 of film is depleted and is replaced by a new reel, the access door 7 is opened (open position A) to allow access to the internal compartment of the unwinding apparatus, in particular to easily insert an initial flap of film unwound from the reel and positioned and partially wound on the first guiding roller 14, the first pre-stretching roller 11 and one of the second guiding rollers 13. By closing the access door 7 (closed position C) the second pre-stretching roller 12 and the two return rolls 13 abut the film that is wrapped properly and correctly around the pre-stretching and guiding rollers. The free end of the initial flap of film projecting externally from the unwinding unit 1 can be grasped by the operator and fixed to a load 200 to be wrapped.

Thanks to this structure of the unwinding apparatus of the invention it is easy and simple to replace the reels 60 of film and it is also possible to comfortably access the roller means 11, 12, 13, 14 for maintenance operations.