Patent Description:
Self-propelled wrapping machines, also referred to as self-propelled wrapping robots, are machines generally used to wrap loads having variable shapes and sizes and in productions in limited amounts, typically in environments or rooms where fixed or static wrapping machines cannot be used because of the overall dimensions and/or available spaces. Loads are generally formed by pallets on which a group of more or less regularly overlapped products and/or objects, even having different sizes and formats, is arranged.

In other cases, the wrapping, normally for protective purposes, directly concerns the product, which is generally large-sized. A wrapping machine according to preamble of claim <NUM> is known from <CIT>.

The self-propelled wrapping machines include a cart or carriage that supports a vertical upright along which a film unwinding or supplying unit, which houses a reel of plastic film and is generally provided with a plurality of rollers for unwinding and pre-stretching the film, is movable, with alternating rectilinear motion. More precisely, the unwinding unit is provided with a pair of pre-stretching rollers arranged for unwinding the film from the reel and pre-stretching or extending the film by a predefined percentage, and one or more return rollers to divert the film towards the load.

The carriage is usually provided with motorized rear drive wheels and a front driving device which comprises one or more steering wheels, operated by a steering. The steering may be operated via a guide bar by an operator to manually drive the machine in a manoeuvring configuration, or from a feeler element capable of following the external outline or shape of the load in an operational working configuration, in which the self-propelled machine turns autonomously and automatically around the load to wrap it with the film.

The combination of the alternating linear movement of the unwinding unit along the vertical upright and the rotation of the self-propelled machine around the load allows the film to be wrapped around the load so as to form a series of intertwined strips or bands. The plastic film is wrapped to completely bind up the load on all its sides.

The feeler element comprises an arm that extends externally and laterally with respect to the carriage and is provided at the end with an idle wheel capable of following the external outline of the load to be wrapped. The feeler element exerts a predefined elastic compression or thrust force on the load, so as to maintain contact with the aforementioned load and to allow the machine to move reliably around the load according to a trajectory determined by the outline of the load itself.

Self-propelled wrapping machines comprising sensors instead of the feeler element, such as ultrasonic ones, capable of detecting the external surfaces and corners of the load and processing related signals which allow a control unit of the wrapping machine to calculate a wrapping path around the load which avoids collisions, are also known. More precisely, based on the external surfaces and corners of the load detected by the sensors, the control unit controls the steering wheels and / or the driving wheels of the carriage so as to steer and drive the latter around the load.

In both types of known self-propelled wrapping machines described above, although the wrapping step takes place in a substantially automatic way, i.e., without manual intervention by an operator, the latter is needed both in an initial step of the wrapping process to fix an initial flap of the film to the load or to the underlying pallet and in a final step to cut the film and separate it from the reel.

Therefore, the aforementioned known self-propelled wrapping machines have the disadvantage of not allowing to carry out wrapping processes in a fully automated way, that is, without any manual intervention by operators.

An object of the invention is to improve the known self-propelled wrapping machines arranged to wrap a load with an extensible plastic film.

Another object is to provide a self-propelled wrapping machine which allows to wrap a load with a film in a full automatic way, without requiring any manual intervention by an operator.

A further object is to provide a self-propelled wrapping machine which allows to make firm and stable wrappings.

A first aspect of the invention provides a self-propelled wrapping machine according to claim <NUM>.

A second aspect of the invention provides a wrapping method according to claim <NUM>.

The invention can be better understood and implemented with reference to the attached drawings which illustrate an exemplary and non-limiting embodiment thereof, in which:.

Referring to <FIG>, a self-propelled wrapping machine <NUM> according to the invention is illustrated, that is movable on a supporting plane P (for example the ground or floor of a production site) around a load <NUM> to wrap the latter with a film <NUM> made of a plastic material, in particular of the cold-extensible type, during a wrapping cycle. The load <NUM> consists, for example, of one or more products arranged on a pallet.

The self-propelled wrapping machine <NUM> comprises a self-propelled or mobile carriage <NUM> and an upright <NUM> fixed thereto and slidably supporting an unwinding unit <NUM>. The unwinding unit <NUM> is provided with a reel <NUM> of a film <NUM> and roller means <NUM>, <NUM>, <NUM> for unwinding and pre-stretching the film <NUM>. The upright <NUM> is substantially vertical.

The self-propelled wrapping machine <NUM> further comprises a first gripping unit <NUM> and a second gripping unit <NUM> both fixed to a rear supporting frame <NUM> of the carriage <NUM> and a movable anchoring element <NUM> to which an initial flap of film 50a unwound from the reel <NUM> can be removably fastened. More precisely, the anchoring element <NUM> is provided with locking means <NUM> which can be selectively operated in a closed position C or in an open position A respectively to tighten or release an initial flap of film 50a. The initial flap of film 50a is generated in a previous wrapping cycle performed by the self-propelled wrapping machine or is manually unwound from a new reel <NUM> by an operator.

The carriage <NUM>, in particular the rear supporting frame <NUM>, further comprises a housing <NUM> adapted to receive and support the anchoring element <NUM>, when the self-propelled wrapping machine <NUM> is not functioning or during the wrapping step of the load <NUM>, as better explained in the description below.

The first gripping unit <NUM> that is supported by the carriage <NUM>, in particular by means of the supporting frame <NUM>, is mobile and adapted to position and release the anchoring element <NUM>, associated with the initial flap of film 50a, which is tightened by the locking means <NUM> operated in the closed position C, on the supporting plane P adjacent to the load <NUM> in an initial step of a wrapping cycle of the load. The first gripping unit <NUM> is also adapted to grasp and lift the anchoring element <NUM> and operate the locking means <NUM> in the open position A so as to release the initial flap of film 50a after at least one turn travelled by the self-propelled wrapping machine <NUM> around the load <NUM>, wrapping the latter with the film <NUM> delivered by the unwinding unit <NUM>, i.e., after the film <NUM> has been partially wrapped and therefore fastened to the aforementioned load <NUM>.

The second gripping unit <NUM> that is supported by the carriage <NUM>, in particular via the supporting frame <NUM>, is mobile and configured to cut a portion of the film <NUM> comprised between the load <NUM> and the unwinding unit <NUM>, to retain a new initial flap of film 50a made by cutting the portion of the film <NUM> and transfer the new initial flap of film to the anchoring element <NUM> positioned in the housing <NUM> so as to be tightened by the locking means <NUM>, in a final step of the wrapping cycle.

The first gripping unit <NUM> comprises first gripping means <NUM> configured to grasp and tighten the anchoring element <NUM>. The first gripping unit <NUM> is movable between a retracted configuration R, in which the first gripping means <NUM> are adjacent to the carriage <NUM>, and a gripping/releasing configuration G, in which the first gripping means <NUM> are spaced apart from the carriage <NUM> and adjacent to the supporting plane P, in particular for grasping or releasing the anchoring element <NUM> positioned on the supporting plane P.

The first gripping unit <NUM> comprises a first arm <NUM> slidably connected to the carriage <NUM> and movable along a first operating direction H, in particular substantially parallel to the supporting plane P, and a second arm <NUM> connected to a supporting end 15a of the first arm <NUM> and extendable/retractable along a second operating position V, in particular substantially orthogonal to the supporting plane P, and supporting the first gripping means <NUM>.

The first arm <NUM> is slidably supported by a pair of guiding supports <NUM>, fixed to the rear supporting frame <NUM>, and is moved by first driving means <NUM>, <NUM>, <NUM>, <NUM> along the first operating direction H between a retracted position and an extended position in which the supporting end 15a thereof is respectively more adjacent to, and more spaced from, the carriage <NUM>.

The first driving means comprise, for example, a first electric motor <NUM> fixed to the supporting frame <NUM> and driving by means of a first reducer <NUM> a pinion <NUM> engaged with a rack <NUM> fixed to the first arm <NUM>. The pinion <NUM> rotating, when driven by the first electric motor <NUM>, moves in two opposite directions the rack <NUM> and thus the first arm <NUM> linearly along the first operating direction H.

The second arm comprises, for example, a stem <NUM> slidably supported by a supporting guide <NUM> fixed to the supporting end 15a of the first arm <NUM>. The second gripping means <NUM> are fastened to an operating end 16a of the stem <NUM>.

The stem <NUM> is moved along the second operating position V by second driving means <NUM>, <NUM>, <NUM>. Second driving means comprise elastic means <NUM> arranged to push and hold the stem or second arm <NUM> in a maximum extension configuration, in which the first gripping means <NUM> are further spaced from the supporting guide <NUM>. The second driving means further comprise a first electric motor <NUM>, fixed to the supporting end 15a of the first arm <NUM> and connected and acting on the first gripping means <NUM> by means of a flexible element <NUM> so as to move the stem <NUM> in opposition to the first elastic means <NUM>, i.e., bringing the first gripping means <NUM> closer to the supporting guide <NUM>.

The elastic means <NUM> comprise, for example, a coaxial spring mounted on the stem <NUM> between the supporting guide <NUM> and the gripping means <NUM> and the flexible element <NUM> comprises, for example, a metal cable.

Alternatively, the second driving means may comprise a linear electrical actuator adapted to support and move the first gripping means <NUM> along the second operating direction V in both directions.

The second driving means <NUM>, <NUM>, <NUM> are configured to move the second gripping means <NUM> along the second operating position V between a raised position S, in which the second gripping means <NUM> are farther away from the supporting plane P, and a first and a second lowered position D1, D2 in which the second gripping means <NUM> are closer to the supporting plane P (<FIG>).

More precisely, in the retracted configuration R of the first gripping unit <NUM>, the stem <NUM> and first gripping means <NUM> are positioned by the second driving means in the first lowered position D1 so as to position the anchoring element <NUM> in the housing <NUM>. In the gripping/releasing configuration G of the first gripping unit <NUM>, the first gripping means <NUM> are positioned in the second lowered position D2 so as to release or take the anchoring element <NUM> on/from the supporting plane P.

In the lowered positions D1, D2 the second driving means <NUM>, <NUM>, <NUM> can be further activated to move towards the supporting plane P and then return to the first or second lowered position D1, D2, with a stroke of limited amplitude, the first gripping means <NUM> in order to operate and bring the locking means <NUM> of the anchoring element <NUM> to the open A or closed C position, as better explained in the description below.

The first gripping means <NUM> comprise, for example, a sleeve or bushing <NUM> provided with an inner cavity adapted to receive a gripping portion 31a of the locking element <NUM> and electromagnet means <NUM>, in particular associated with the sleeve <NUM>, selectively activatable or deactivatable respectively to grasp or release the gripping portion 31a, made of ferromagnetic material.

A plate <NUM> is fastened to the sleeve <NUM> which is abutted by the coil spring <NUM> and to which the flexible element <NUM> is fastened.

Sensor means <NUM> are associated with the first gripping means <NUM> and arranged to detect the presence of the anchoring element <NUM> and the correct positioning with respect to the latter of the first gripping unit <NUM> and/or of the self-propelled wrapping machine <NUM>. The sensor means <NUM> are fixed to the plate <NUM> by means of a bracket <NUM>.

With particular reference to <FIG>, the anchoring element <NUM> comprises a central pin <NUM> having a first end that forms the gripping portion 31a adapted to be grasped and retained by the first gripping unit <NUM>, in particular by the first gripping means <NUM>, and a first plate <NUM> adapted to abut the supporting plane P and slidably connected to an opposite second end of said central pin <NUM>.

The locking means <NUM> comprising a second plate <NUM> superimposed on the first plate <NUM> and fixed to the central pin <NUM> and mobile between a closed position C, in which it abuts the first plate <NUM>, in particular to tighten the initial flap of film 50a against it, and an open position A, in which it is spaced from the first plate <NUM>, in particular to release the initial flap of film 50a.

The locking means <NUM> also comprise a locking/unlocking mechanism <NUM> of the known type, interposed between the central pin <NUM> and the first plate <NUM> and configured to switch the position of the second plate <NUM> between the open position A and the closed position C when the central pin <NUM> and the second plate <NUM> are pushed against the first plate <NUM> by the first gripping unit <NUM>, more precisely by the first gripping means <NUM>.

The anchoring element <NUM> has an overall weight, for example of at least <NUM>, such as to ensure retaining the initial flap of film 50a in the established position on the supporting plane P without moving during the first wrapping turn with the film <NUM> of the self-propelled wrapping machine <NUM> around the load <NUM>.

The second gripping unit <NUM> comprises second gripping means <NUM> adapted to grasp and retain the film <NUM> and cutting means <NUM> adapted to cut the film <NUM>.

The second gripping unit <NUM> is movable between a gripping and cutting position B1, a transfer position B2 and a rest position B3.

In the gripping and cutting position B <NUM> the cutting means <NUM> and the second gripping means <NUM> are spaced from the carriage <NUM> respectively to cut the portion of the film <NUM>, comprised between the unwinding unit <NUM> and the load <NUM>, and to grasp and tighten the new initial flap of film 50a generated by cutting the film <NUM>. In the transfer position B2 the cutting means <NUM> and the second gripping means <NUM> are adjacent to the carriage <NUM> and the anchoring element <NUM> positioned in the housing <NUM> of the carriage <NUM> so as to transfer the new initial flap of film 50a to the locking means <NUM> of the anchoring element <NUM>, arranged in the open position A. In the rest position B3 the cutting means <NUM> and the second gripping means <NUM> are adjacent to the carriage <NUM> and spaced from the housing <NUM>, in particular so as not to interfere with the wrapping of the film <NUM> around the load and with the movement of the first gripping unit <NUM>. The second gripping unit <NUM> comprises a third arm <NUM> having a respective first end 17a connected to the carriage <NUM> and a respective second end 17b supporting the second gripping means <NUM> and the cutting means <NUM>. The third arm <NUM> is, for example, rotatably connected to the carriage <NUM> and movable along a curved path through the gripping and cutting position B1, the transfer position B2 and the rest position B3.

Third driving means <NUM>, <NUM> fastened to the carriage <NUM> are provided to rotate the third arm <NUM> between the gripping and cutting position B1, the transfer position B2 and the rest position B3.

The third driving means comprise, for example, a second electric motor <NUM> fastened to the supporting frame <NUM> and driving the third arm <NUM> in rotation about a vertical axis, by means of a second reducer <NUM>.

The second gripping means <NUM> comprise, for example, a gripper with a film locking mechanism <NUM> which is mechanically operated, in particular by the film <NUM> itself in the closed position and by an abutment <NUM> fixed to the supporting frame <NUM> of the carriage <NUM> in the open position, as better explained in the description below.

The cutting means <NUM> comprise, for example, a fixed "V"-shaped blade.

The unwinding unit <NUM> comprises frame means adapted to support the reel <NUM> and roller means <NUM>, <NUM>, <NUM> which are arranged to unwind the film <NUM> from the reel <NUM>, pre-stretch and divert the film towards the load <NUM>. More precisely, the roller means comprise a pair of pre-stretching rollers <NUM>, <NUM> and one or more guide rollers <NUM>. The pair of pre-stretching rollers <NUM>, <NUM> comprises a first pre-stretching roller <NUM> and a second pre-stretching roller <NUM>, rotating around respective longitudinal axes with different speeds so as to stretch or extend the film <NUM> during unwinding from the reel <NUM> and before wrapping on the load <NUM>.

The unwinding unit <NUM> further comprises folding means <NUM> adapted to transversely roll up and/or narrow the film <NUM> exiting from the roller means <NUM>, <NUM>, <NUM>, so as to reduce a band width or largeness thereof or make a rolled-up or pleated portion and form a cord or strip or the like of film. The film <NUM> pleated or rolled to form a cord or strip can be grasped more firmly by the second gripping means <NUM> and more easily cut by the cutting means <NUM> of the second gripping unit <NUM> and form the two initial flaps 50a and the end one 50b.

The carriage <NUM> comprises two or more drive wheels <NUM>, a steering wheel and guiding means <NUM> for guiding the self-propelled wrapping machine <NUM> along a wrapping path around the load <NUM>. More precisely, the self-propelled wrapping machine <NUM> is provided with a pair of rear drive wheels <NUM>, at least one of which driven by motor means, and a front steering wheel. In the embodiment illustrated in the figures, the guiding means <NUM> comprise a feeler arm <NUM>, of known type, arranged to follow an external outline of the load <NUM> during the wrapping step and connected to the steering wheel to steer the latter and move the carriage <NUM> along the wrapping path.

Alternatively, in a variant not shown of the self-propelled wrapping machine <NUM>, the latter may comprise sensors capable of detecting external surfaces and edges of the load <NUM> and processing related signals, and a control unit adapted to receive said signals from the sensors, calculate a wrapping path such as to avoid collisions with the load <NUM> and control the guiding means <NUM> so as to guide the self-propelled wrapping machine <NUM> along the wrapping path. In this variant, the guiding means <NUM> comprise actuation means controlled by the control unit and arranged to steer the steering wheel or driving means also controlled by the control unit and arranged to vary the speed of the drive wheels <NUM>.

The control unit of the self-propelled wrapping machine <NUM> is also arranged to operate and control in a coordinated way the movement of the carriage <NUM> around the load <NUM>, the supply of film <NUM> from the unwinding unit <NUM>, the movement thereof along the upright <NUM>, the operation of gripping units <NUM>, <NUM> in the different steps of the wrapping cycle.

The self-propelled wrapping machine <NUM> is also provided with sensor means, of known type, for example comprising photocells or capacitive sensors, or the like, capable of detecting the overall dimensions and sizes of the load <NUM> and the distances between the latter and the self-propelled wrapping machine <NUM> during operation. The signals of the sensor means are sent to the control unit of the machine to allow the correct execution of the different steps of the wrapping cycle.

In operation, the self-propelled wrapping machine <NUM> of the invention performs wrapping cycle of the load <NUM> according to the following steps.

In a first initial step the self-propelled wrapping machine <NUM> is positioned adjacent to the load <NUM>, and thus activated so as to move around the load <NUM> for at least one turn in order to calculate and identify a defined initial position W of wrapping cycle start. More precisely, thanks to sensor means which detect the overall dimensions and sizes of the load <NUM>, the control unit is capable to stop the self-propelled wrapping machine in the defined initial position W.

The first gripping unit <NUM> is arranged in the retracted configuration R and the first gripping means <NUM> are engaged with the gripping portion 31a of the anchoring element <NUM>, which is arranged in the housing <NUM> of the supporting frame <NUM> of the carriage <NUM>. More precisely, the first arm <NUM> is arranged in the retracted position R and the second arm <NUM> in the first lowered position D1 so that the gripping portion 31a of the anchoring element <NUM> is inserted in the sleeve <NUM> of the first gripping means <NUM>.

The anchoring element <NUM> is associated with the initial flap of film 50a unwound from the reel <NUM>, for example obtained by cutting the film at the end of a previous wrapping cycle. In particular, the initial flap of film 50a is retained by the locking means <NUM> arranged in the closed position C, that is, tightened between the two plates <NUM>, <NUM> of the anchoring element <NUM>.

In a second step, the first gripping means <NUM> are operated to grasp and tighten the anchoring element <NUM> and the first gripping unit <NUM> is moved from the retracted configuration R to the gripping/releasing configuration G in which the first gripping means <NUM> are adjacent to the load <NUM> and to the supporting plane P to release on the latter the anchoring element <NUM> to which the initial flap of film 50a is fastened.

More in detail, the electromagnet means <NUM> of the first gripping means <NUM> are activated so as to grasp and lock the gripping portion 31a of the anchoring element <NUM> and the second arm <NUM> is moved by the second driving means <NUM>, <NUM>, <NUM> so as to move the first gripping means <NUM> from the first lowered position D1 to the raised position S in order to lift the anchoring element <NUM> from the housing <NUM>. To this end, the first motor <NUM> winds the cable <NUM> to lift the first gripping means <NUM> by compressing the spring <NUM>. The first arm <NUM> is then moved by the first driving means <NUM>, <NUM>, <NUM>, <NUM> along the first operating direction H between the retracted position and the extended position and then the second arm <NUM> is moved by the second driving means <NUM>, <NUM>, <NUM> so as to move the first gripping means <NUM> from the raised position S to the second lowered position D2 to put the anchoring element <NUM> down on the supporting plane P. To this end, the first motor <NUM> partially and limitedly releases the cable <NUM> to allow the spring <NUM> to lower the first gripping means <NUM>.

In a third step, the anchoring element <NUM> that retains the initial flap of film 50a is released by the first gripping unit <NUM>. More precisely, the electromagnet means <NUM> of the first gripping means <NUM> are deactivated to allow disengagement of the sleeve <NUM> from the gripping portion 31a of the anchoring element <NUM>.

The first gripping unit <NUM> is then returned from the gripping/release configuration G to the retracted configuration R.

In a fourth step, the self-propelled wrapping machine <NUM> is moved around the load <NUM> for at least one turn so as to wrap the load with the film <NUM> supplied by the unwinding unit <NUM>. The film <NUM>, whose initial flap 50a is fixed to the anchoring element <NUM>, is thus wrapped, and adheres and fastens firmly to the load <NUM>. The film <NUM> is supplied by the unwinding unit <NUM> at full height, i.e., not rolled or narrowed transversely.

In a fifth step, the self-propelled wrapping machine <NUM> is stopped in the defined initial position W to allow the first gripping unit <NUM> to grasp and lift the anchoring element <NUM> from the supporting plane P after having operated the locking means <NUM> in the open position A so as to disengage the initial flap of film 50a from the anchoring element <NUM>. More precisely, when the self-propelled wrapping machine <NUM> is stopped, the first gripping unit <NUM> is moved from the retracted configuration R to the gripping/releasing configuration G in which the first gripping means <NUM> are adjacent to the load <NUM> and to the supporting plane P and capable of grasping the anchoring element <NUM> and operating the locking means <NUM> in opening. To this end, the first gripping means <NUM> are moved by the first driving means <NUM>, <NUM>, <NUM> in the second lowered position D2 so as to engage the sleeve <NUM> in the gripping portion 31a and tighten it by activating the electromagnet means <NUM>. The first gripping means <NUM> are further lowered and then returned to the second lowered position D2 to operate the locking/unlocking mechanism <NUM> of the anchoring element <NUM> which causes the second plate <NUM> of the locking means <NUM> to move in the open position A where the initial flap of film 50a can be disengaged. The first gripping unit <NUM> then lifts from the supporting plane P the anchoring element <NUM>, disengaged from the initial flap of film 50a and with the locking means <NUM> in the open position A, and transfers the anchoring element to the housing <NUM> of the supporting frame <NUM> of the carriage <NUM>. To this end, the second arm <NUM> is moved by the second driving means <NUM>, <NUM>, <NUM> (in particular by the first motor <NUM> via the cable <NUM>) along the second operating direction V so as to move the first gripping means <NUM> from the second lowered position D2 to the raised position S.

Then the first arm <NUM> is moved by the first driving means <NUM>, <NUM>, <NUM>, <NUM> along the first operating direction H between the extended position and the retracted position and then the second arm <NUM> is moved by the second driving means <NUM>, <NUM>, <NUM> along the second operating direction V (in particular by the spring <NUM>) so as to move the first gripping means <NUM> from the raised position S to the first lowered position D1 to put the anchoring element <NUM> down in the housing <NUM> of the carriage <NUM>. The anchoring element <NUM> has the locking means <NUM> still in the open position A with the second plate <NUM> spaced from the first plate <NUM>.

In a sixth step, the self-propelled wrapping machine <NUM> is activated again to move around the load <NUM> for a defined number of turns so as to wrap the load with the film <NUM> according to a defined wrapping configuration. The wrapping step comprises, during the rotation of the carriage <NUM> around the load <NUM>, moving the unwinding unit <NUM> with alternate motion along the upright <NUM> and simultaneously dispensing the pre-stretched film <NUM> from the unwinding unit <NUM>.

In the last wrapping turn, the folding means of the unwinding unit <NUM> are operated so as to transversely roll up and/or narrow the film <NUM> exiting from the unwinding unit <NUM>. For example, the film <NUM> is narrowed so as to form a cord or strip of limited width which can be grasped and retained more firmly by the second gripping means <NUM> and cut more effectively and easily by the cutting means <NUM> of the second gripping unit <NUM>.

In a seventh step, at the end of the wrapping, the self-propelled wrapping machine <NUM> is stopped in a defined final position Z, possibly coinciding with the initial position W, and the second gripping unit <NUM> is moved by the third driving means <NUM>, <NUM> from the rest position B3, adjacent to the carriage <NUM>, in the gripping and cutting position B1 to allow the second gripping means <NUM> and the cutting means <NUM> respectively to grasp and cut the portion of film <NUM> between the unwinding unit <NUM> and the load <NUM> and create a new initial flap 50a and an end flap 50b associated with the load <NUM> (<FIG> and <FIG>). More precisely, during the rotation, the second gripping means <NUM> and the cutting means <NUM> intercept and stretch the film <NUM> which thereby mechanically drives the locking mechanism <NUM> of the gripper of the second gripping means <NUM> in the closed position and is simultaneously cut by the blade of the cutting means <NUM>, generating the new initial flap 50a retained by the locking mechanism <NUM> and the end flap 50b associated with the load <NUM>.

In an eighth step, the second gripping unit <NUM> is moved by the third driving means <NUM>, <NUM> in the transfer position B2 in order to transfer and release the new initial flap of film 50a to the locking means <NUM> of the locking element <NUM> (positioned in the housing <NUM> of the supporting frame <NUM> of the carriage <NUM>) arranged in the open position A. More precisely, by rotating in the transfer position B2, the second gripping unit <NUM> inserts the initial flap of film 50a between the two plates <NUM>, <NUM> of the anchoring element <NUM> spaced apart in the open position A of the locking means <NUM>. The locking mechanism <NUM> is operated in the open position, so as to release the film <NUM>, thanks to the contact of a control lever <NUM> of said locking mechanism of the gripper <NUM> with an abutment <NUM> fixed to the supporting frame <NUM>.

The locking means <NUM> are operated in the closed position C by the first gripping unit <NUM>, further lowering the first gripping means <NUM> from the first lowered position D1 and then returning them to such a first lowered position D1 so as to operate the locking/unlocking mechanism <NUM> of the anchoring element <NUM> which moves the second plate <NUM> of the locking means <NUM> in the closed position C to tighten the initial flap of film 50a against the first plate <NUM>.

The second gripping unit <NUM> disengaged from the initial flap of film 50a is then returned by the third driving means <NUM>, <NUM> to the rest position B3.

Therefore the self-propelled wrapping machine <NUM> of the invention allows to wrap a load <NUM> with a film <NUM> in a fully automatic way, i.e., without requiring any manual intervention by the operator, both in an initial step of the wrapping cycle, in which an initial flap of film 50a must be retained during a first wrapping turn of the film <NUM> around the load <NUM>, and in a final step, in which the film <NUM> must be cut and the initial flap of film generated by the cut must be retained.

The anchoring element <NUM>, which is positioned and released by the first gripping unit <NUM> on the supporting plane P adjacent to the load <NUM>, thanks to the locking means <NUM> and its weight, allows the initial flap of film 50a to be firmly and safely retained in an initial step of the wrapping cycle of the load <NUM> in which said initial flap of film 50a is fixed to the load <NUM> by the same film <NUM> wound around the load.

The anchoring element <NUM> is then recovered from the first gripping unit <NUM> after the film <NUM> has been suitably wrapped and fixed to the load <NUM> with at least one wrapping turn, so as not to hinder the subsequent wrapping step. These operations are performed completely automatically, managed by the control unit of the self-propelled wrapping machine <NUM>.

Also the operation which involves gripping and cutting the film <NUM> to obtain the two initial and end flaps of film 50a, 50b is performed at the end of the wrapping cycle completely automatically by the self-propelled wrapping machine <NUM>.

The method according to the invention for wrapping a load <NUM> by means of the self-propelled wrapping machine <NUM> above described and illustrated in <FIG> comprises a wrapping cycle that includes the following operating steps:.

According to the method of the invention, the anchoring element <NUM> retains the initial flap of film 50a by locking means <NUM> operated in the closed position C by the first gripping unit <NUM>, in particular by first gripping means <NUM> of the latter also configured to grasp and tighten the anchoring element <NUM>.

According to the method of the invention, the first gripping unit <NUM> disengages the initial flap of film 50a from the anchoring element <NUM> by operating the locking means <NUM> in the open position A, in particular by the first gripping means <NUM>.

The method also comprises, before positioning the self-propelled wrapping machine <NUM> in the defined initial position W, moving the self-propelled wrapping machine around the load <NUM> for at least one turn so as to calculate and identify the defined initial position W.

Claim 1:
Self-propelled wrapping machine (<NUM>) movable on a supporting plane (P) around a load (<NUM>) to wrap the latter with a film (<NUM>) made of plastic material during a wrapping cycle, comprising a self-propelled carriage (<NUM>) and an upright (<NUM>) fixed to said carriage (<NUM>) and slidably supporting an unwinding unit (<NUM>) provided with at least one reel (<NUM>) of film (<NUM>), wherein it comprises:
- an anchoring element (<NUM>) provided with locking means (<NUM>) selectively operable in a closed position (C) or in an open position (A) respectively to tighten or to release an initial flap of the film (50a) unwound from the reel (<NUM>); characterized in that the wrapping machine further comprises:
- a first gripping unit (<NUM>) supported by said carriage (<NUM>), movable and adapted to position and release said anchoring element (<NUM>), which is associated with said initial flap of film (50a) tightened by said locking means (<NUM>) arranged in the closed position (C), on said supporting plane (P) adjacent to said load (<NUM>) in an initial step of said wrapping cycle, and adapted to grasp and lift said anchoring element (<NUM>) and activate in the open position (A) said locking means (<NUM>) so as to release said initial flap of film (50a) after at least one turn travelled by said self-propelled wrapping machine (<NUM>) around said load (<NUM>) while wrapping the latter with said film (<NUM>) delivered by said unwinding unit (<NUM>).