IT201900000241A1 - Machine for wrapping web materials. - Google Patents

Description

DESCRIPTION

The present invention relates to a machine for wrapping web-like materials.

In various industrial sectors, ribbon-like materials are used, packaged in the form of reels obtained by winding the materials themselves on special rods that act as supports during the winding. When a reel has been fully formed, its rod is pulled out for reuse. The web-like materials wound on reels are generally destined to undergo different transformations depending on the specific applications and can be, for example, paper or non-woven fabric. The transformations can include, for example, the unwinding and rewinding of the material in order to produce rolls with a diameter smaller than that of the starting reels, embossing operations intermediate between the unwinding and the subsequent rewinding, the transversal cutting of the rolls to obtain products with axial length shorter than that of the starting reel, etc. The machines with which the winding is carried out are generally called "winders" and typically include a structure that allows the web material to slide on a winding roller against which the rod on which the reel is formed is pushed. The latter, during its formation, is kept in contact with the winding roller due to the thrust exerted through the rod which, in turn, is held by special supports which allow it to be translated along the guides formed in the aforementioned structure. Cyclically, when a reel is completed, that is, it has a diameter of a predetermined value, the web material is interrupted, the completed reel is moved away from the winding roller by means of a movement that leads it to an unloading station while it is still on the relative rod. winding, and another winding rod is placed on the winding roll to form a new reel. The take-up rods are generally stored in a machine superstructure in a position overlying the take-up roll. It is therefore necessary to provide a mechanism for picking up the winding rods from the storage point and placing them in the area of the machine where the reels are formed.

The present invention relates, in particular, to the removal of the winding rods from the storage point of the same and their handling during the winding of the web material and aims to provide a structurally simple, precise and precise control system for the winding rods. reliable. This result has been achieved, in accordance with the present invention, by adopting the idea of making a machine having the characteristics indicated in claim 1. Other characteristics of the present invention are the subject of the dependent claims.

Thanks to the present invention, it is possible to realize a machine for winding web-like materials which ensures an improved continuity of growth of the diameter of the coils as they are formed and a considerable precision in the positioning of the rods in correspondence with the winding roller without however introducing particular complexity of mechanical type. Furthermore, a system for picking up and positioning the rods in a machine according to the present invention allows to control the nip pressure at the winding roller / reel interface and offers the possibility of improving the control of the movement of the reels towards the parking point. of finished coils.

These and further advantages and characteristics of the present invention will be better understood by every person skilled in the art thanks to the following description and the attached drawings, provided by way of example but not to be considered in a limiting sense, in which:

- Fig.1 represents a schematic perspective view of an arm for moving the winding rods in a machine according to a possible example of embodiment of the present invention;

- Figs. 2-5 schematically show a machine according to a possible example of embodiment of the present invention in different stages of production of a reel of web material, with machine parts not shown in order to better highlight others;

Fig.6 schematically represents a machine according to a further example of embodiment of the present invention;

- Fig.7 represents a schematic plan view of a rod;

- Figures 8 and 9 illustrate a further example of embodiment of a machine according to the present invention;

- Fig. 10 is a simplified block diagram relating to a possible configuration of a control system for the movements of the arms in accordance with the present invention;

Fig.11 represents a schematic perspective view of an arm for moving the winding rods in a machine according to another embodiment of the present invention;

- Fig.12 schematically represents a machine in accordance with another example of implementation of the present invention which provides for the use of the arm of Fig.11.

Reduced to its essential structure and with reference to the figures of the attached drawings, a machine (M) according to the present invention comprises a winding roller (1) on which the web material intended to be wound passes. The winding roller (1) cooperates with a winding rod (2) on which the web material is wound to form a reel (B). The winding roller (1) is positioned in a structure (3) provided with sides (30) on which are formed two corresponding linear guides (31) parallel to each other and oriented according to a predetermined direction (L) which defines a direction of advancement of the winding rod (2) while the respective coil (B) is formed on the rod itself. The winding roller (1) is oriented transversely to said sides, so that its rotation axis (1A) is horizontal. The machine in question is served by a warehouse in which several winding rods (2) can be stored and by a mechanism for withdrawing the rods (2) from the warehouse (S). The rods (2), according to a per se known configuration, have ends (20) shaped to be grasped by a gripping device. In practice, the rods (2) have a central cylindrical body (21) which forms the winding surface proper, that is the surface on which the web material is wound, and two circular ends (20) which define two corresponding gripping portions auction. As shown in Fig. 7, between the central body (21) and each of the ends (20), the rods (2) have annular grooves which define both the rolling surfaces (22) of the rods themselves on the aforementioned guides (31) and further parts (23) which can be gripped by gripper means as further described below.

For example, the web material is paper produced in a paper machine. Preferably, said magazine is constituted by a superstructure (32) of the machine arranged at a greater height of the winding roller (1) and comprising supports (33) for supporting and rolling the winding rods (2) with an output side ( 33E) from which the rods (2) can be taken, as further described below.

In accordance with the present invention and with reference to the example shown in Figs. 1-5, the mechanism for withdrawing the rods (2) from the magazine (S) comprises two arms (45), that is an arm (45) for each side of the structure (3). Each arm consists of two elements (4, 5) hinged together with the hinge axis (A45) parallel to the rotation axis of the winder roller (1). With reference to the example shown in the attached drawings, said arms (45) are positioned externally to the sides (30) of the machine. As further indicated below, the first element (4) of each arm (45) can rotate around the axis (A45) of the relative hinge connection with the second arm (5) and the second element (5) can rotate around the axis of the winding roller (1). In this way, the first element (4) of each arm (45) can rotate with respect to the second element (5) which, in turn, can rotate around the axis of the winding roller (1). The second element (5) can be linked to the basic structure of the machine (M) by means of a hinged connection with axis coinciding with the axis (1A) of the winding roller (1), as in the example of realization illustrated in Figs. 2-5, or it can be connected to the superstructure (32) of the machine (M) by means of a hinge connection with axis parallel to the axis (1A) of the winding roller (1), as in the example of embodiment illustrated in Fig. 6 .

Preferably, the rotation of the first element (4) of each arm around the axis (A45) is controlled by a first electric gearmotor (M4) and the rotation of the second element (5) around the axis (1A) of the winding roller ( 1) is controlled by a second electric gearmotor (M5). In this configuration, the gearmotors (M4, M5) are controlled independently, so that the rotation of each element (4, 5) can be controlled independently from the rotation of the other element of the same arm.

With reference to the example shown in the attached drawings, said elements (4, 5) are formed by metal plates, or by bodies with prevalent longitudinal development in which two dimensions are prevalent with respect to the third, and are hinged together in proximity to two respective end portions (40, 50) side by side. The first element (4) of each arm (45) has a gripping device suitable for gripping a corresponding end of a winding rod (2), as further described below.

For example, said gripping device is formed by a gripper (42) comprising a jaw (420) hinged on a free end (421) of the first element (4), which acts as a fixed jaw of the gripper. The said free end (421) is concave, with the concavity facing outwards, and the jaw (420) is mobile, being hinged on the free end of the element (4), and has an internal side (422) also it is concave, so that the concavities (421, 422) respectively presented by the fixed jaw and by the movable jaw define, in cooperation with each other, a seat adapted to receive a corresponding end of a winding rod (2). With reference to the example shown in the drawings, said seat, seen from the side, is substantially circular in shape. For example, the movable jaw (420) can be rotated on the end (421) of the first element (4) by means of a linear actuator (43) which is mounted on one side on an appendage (423) of the first element (4) and, on the opposite side, on an appendix (424) of the same movable jaw (420). For example, the appendix (423) may consist of an upper wing of the first element (4). The appendix (424) of the movable jaw (420) can also be an upper appendage of the latter, so that the actuator (43) does not interfere with the gripping of the winding rods (2). The connection between the jaw (420) and the first element (4) of the arm (45) can be made, for example, by means of a hinge (425) with an axis transversal to the first element (4) and to the jaw (420). The actuator (43) controls the rotation of the movable jaw (420) around the axis of the hinge (425) as schematically indicated by the double arrow in Fig.1. In Fig.1 the jaw (420) is in the gripping configuration, being rotated towards the fixed jaw formed on the free end of the first element (4). In practice, the actuator (43) determines the opening and closing of the seat for gripping one end of a winding rod (2) by rotating the movable jaw (420) from and towards the first element (4) around the hinge axis (425). Preferably, the movable jaw (420) is formed by a metal plate located laterally offset with respect to the end (421) of the first element (4). The device described above is, therefore, a gripper arranged on the first element (4) of each arm (45) for gripping and respectively releasing the winding rods (2). The movable jaw (420) can be moved by an actuator different from the one described above, such as a rotary actuator (not shown in the drawings) applied to the element (4) and acting on the movable jaw (420).

Each arm (45) has an external side, facing the outside of the machine (M), and an internal side facing the machine (M).

For each arm (45), the first gearmotor (M4) is applied on the external side of the first element (4), in correspondence with the connection point with the second element (5). In the example of Fig.1, the stator of the gearmotor (M4) is on the element (4), while the rotor is connected to the element (5). It is understood, however, that the stator of the gear motor (M4) can be on the element (5) and the rotor in this case will be connected to the element (4). Similarly, the second gearmotor (M5) is applied on the external side of the second element (5), at the connection point of the latter to the respective side (30) of the machine (M). In the example of Figs. 2-5, the stator of the gearmotor (M5) is on the element (5), while the rotor is connected to the connection point of the element (5) with the respective side (30) of the machine ( M). However, the stator of the gearmotor (M5) can be on said connection point and the rotor in this case will be connected to the element (5).

Figs. 2-5 illustrate a possible cycle of engagement, handling and release of a winding rod (2A) by means of two arms (45) made as described above. In Figs. 2-5 the rod taken over and moved by the arms (45) is indicated with the reference "2A" to distinguish it from the rods that remain on the superstructure (32).

In Fig. 2 you can see a reel (B) in the completion phase, still close to the winding roller (1). In the same Fig. 2 the arms (45) are seen in the pick-up position of a rod (2A) from the outlet side (33E) of the superstructure (32), with the pliers (42) of the ends (20) of the same rod (2A).

In Fig. 3 the arms (45) are in position for positioning the rod (2A), previously taken from the superstructure (32), on the winder roller (1). In the passage from the configuration of Fig. 2 to the configuration of Fig. 3, the first element (4) of each arm (45) rotates around the axis (A45), while the second element (5) rotates around the axis (1A ). The combined rotation of the elements (4, 5) of the arms (45) determines the positioning of the rod (2A) against the winder roller (1) on the upper side of the latter. Meanwhile, on the exit side (33E) of the superstructure (32) another rod (2) has taken the place of the one previously taken from the arms (45). In correspondence with the positioning of the rod (2A) on the winding roller (1), the web material with which the reels are formed is interrupted.

In Fig.4A you can see the rod (2) placed by the arms (45) in front of the winding roller (1) and the material that forms the new reel (NB) is wound on it. The completed bobbin (B) has been pulled out. Also in the passage from the configuration of Fig.3 to the configuration of Fig.4A, the combined rotation of the elements (4, 5) around the axes (45) and (1A) determines the movement of the rod (2A). In the passage between the position of Fig. 3 and the position of Fig. 4A, the longitudinal axis (X) of the rod (2A) moves along a trajectory which is first parallel to the external surface of the winding roller (1) and then follows the direction of the guides (31), as schematically illustrated in Fig.4B. In the meantime, due to the effect of the dragging operated by the winding roller (1), the rod (2A) rotates around its own axis, winding on itself the web material which is fed along a predetermined feeding direction upstream of the winding roller (1). in a manner known per se.

Fig. 5 shows a further configuration of the arms (45), upon reaching the predetermined diameter of the reel (NB) with the material (W).

The arms (45) support the ends (20A) of the rod (2A) on the guides (31) of the machine (M) as the diameter of the reel being formed (NB) increases. As previously mentioned, the annular grooves (22) favor the rolling of the rods (2), and therefore of the reels (NB), on the guides (31) of the machine.

It goes without saying that the pliers (42) mounted on the arms (45) do not block the ends (20) of the rods (2) so as not to prevent them from rolling on the guides (31). In practice, the pliers (42) define a removable constraint that allows the arms (45) to move the rods (2) from the superstructure (32) to the contact position with the winding roller (1) and along the guides (31), without however preventing the rods (2) from rotating around their longitudinal axes.

Upon reaching a predetermined final diameter of the new reel (NB), the mounted pliers (42) free the respective ends (20A) of the rod (2A) and the arms (45) can be brought back to the pick-up position of another rod from the superstructure (32) to start a new work cycle. The completed reel is then removed from the machine (M) in a manner known per se.

With reference to the example shown in Fig. 6, the second element (5) of each arm (45) is hinged on the superstructure (32). Everything previously said in relation to the structure and operation of the arms (45) and, more generally, of the machine (M) remains valid. Also in this case, the movements of the rods (2) along the path between the aforementioned warehouse and the winding station where the winding roller (1) acts is determined by the combination of the rotational movements of the first and second element (4, 5) of each arm (45).

As shown in Figs. 8 and 9, the machine (M) is equipped with a carriage (6) mounted on the external side of each of its sides (30) and which can be moved parallel to the same sides of the machine bidirectionally from and towards the winding roller (1) by means of a corresponding drive unit (not visible in the drawings). On said carriage (6) a gripper (60) is applied, controlled by a corresponding actuator (61) also mounted on the carriage (6). This device is known per se (in technical jargon it is commonly called "secondary arm") and, therefore, is not described in greater detail. A possible way of using the trolleys (6) in the context of the present invention is the following. The carriages (6) are approached to the rod (2) on which the coil is being formed (NB), keeping the pliers (60) open. Subsequently, each gripper (60) is closed on a corresponding annular groove (22) to engage the respective end of the rod (2A) next to the gripper (42) of the corresponding arm (45) which, at this point, is opened. In this way, the carriages (6) take delivery of the reel being formed (NB), guaranteeing its support until the final diameter is reached and the pre-selected parking position on the guides (31) is reached. In the meantime, the arms (45) can be brought into the withdrawal position of another rod (2) from the superstructure (32). In Fig. 8 we see the exchange, that is the phase in which the carriages (6) take delivery of the completed reel (B) which is released by the grippers (42) mounted on the arms (45). The trolleys (6) can take delivery of the new reel being formed even if the final diameter of the latter is compatible with the length of the arms (45). Therefore, the arms (45) can anticipate the withdrawal of the rods (2) with respect to reaching the final diameter of the coil to be formed. In Fig. 9 the arms (45) have already picked up a rod and have positioned it in contact with the winding roller (1) while the reel is being completed and is entrusted to the trolleys (6) which can also unwind “pusher” function and accompany the completed reel to a pre-established parking point downstream.

In the context of the present description, by "length of the arms (45)" is meant the sum of the lengths of the elements (4) and (5).

The arms (45) can also be used to adjust the pressure of the nip at the winding roller / reel interface. This pressure, which in general is comprised within the minimum and maximum predetermined values according to the nature or structure of the tape (W) and the winding speed imposed by the winding roller (1), can be adjusted through the reciprocal rotation of the elements (4, 5) of each arm (45) which determines a greater or lesser thrust of the rod (2A) being processed against the winding roller (1). For this purpose, a torque load cell (C4) can also be provided in the hinge for attachment of the first element (4) to the second element (5) and a torque load cell (C5) in the attachment hinge of the second element (5). ) to the machine structure (M). The load cells (C4, C5) of each arm can be connected to a programmable unit (UE) which controls the gearmotors (M4, M5) of the arms (45) according to a program residing in one of its memory sections. The diagram in Fig. 10 illustrates a possible configuration of the connections between the load cells (C4, C5) with the control unit (UE) to which position sensors (P4, P5) are also connected to detect the angular position of the elements (4, 5). The unit (UE) can be programmed not only to perform the movements of the arms (45) as described above but also to adjust the nip pressure according to the readings of the load cells (C4, C5). It goes without saying that the movements of the arms (45), i.e. the movements of the elements (4) and (5) of the arms (45), are synchronized with each other, so that on the two sides of the machine (M) the movements of the arms are coordinated.

In accordance with the present invention, the picking up of the rods (2) from the storage warehouse of the same is performed by two arms (45) which, in addition to picking up the rods (2), also move them along a predefined path which includes their positioning against the unwinding roller (1). Preferably, the arms (45) also control the translation of the rods (2) along the guides (31) as the diameter of the coils being formed increases, until a predetermined diameter is reached.

In accordance with the examples described above, the two arms (45) are each formed by two elements (4, 5) hinged together in such a way that the aforementioned path is formed by a combination of rotary movements around two parallel axes. . One of these axes can coincide with the rotation axis (1A) of the winding roller (1). Alternatively, both said axes can be distinguished from the rotation axis (1A) of the winding roller (1), as indicated by way of example above with reference to Fig.6. Preferably, the two elements (4, 5) are each driven by a corresponding actuator (M4, M5) so that the rotation of each of them can be controlled independently.

In accordance with a further embodiment of the invention, on the outer side of the first element (4) of each of the arms (45) a rotary actuator (7) can be mounted, such as an electric motor, which can be used to control the rotation of the rods (20) around the respective longitudinal axes with predetermined angular velocity. With reference to the example shown in Fig. 11, the actuator (7) is supported by a bracket (70) mounted cantilevered on the external side of the first element (4) of the arm (45) and has an output shaft, oriented parallel to the axis (A45) of the connection hinge between the first and the second element of the arm itself, and facing the gripper (42). A friction disc (71) is applied to said shaft. The actuator (7) is positioned on the bracket (70) so that the friction disc (71) can come into contact with the outer face of the end (20A) of any rod engaged by the respective caliper (42). In practice, the rotation of the discs (71) in contact with the external faces of the two ends (20) of a rod (2) determines the rotation of the latter around its longitudinal axis with angular speed imposed by the actuator (7 ). The actuator is mounted on a trolley (72) to allow its movement on the shelf (70), to and from the end of the arm (45) on which the clamp (42) is mounted. In Fig.11 the said movement of the actuator (7) on the bracket (70) is indicated by the arrow "FA". The movement (FA) is controlled by a corresponding motor member not visible in the drawings. The actuator (7) is moved towards the end of the rod engaged by the caliper (42) when you want to drag the rotating rod due to the contact between the end of the latter and the friction disc (71) . Conversely, the opposite movement of the actuator (7) determines the disengagement of the rod from the friction wheel (71). This mechanism can be useful when the rotation of the rod (2) during the formation of a reel must not be guaranteed exclusively by the pressure against the winder roller (1).

Fig.12 illustrates by way of example the use of the arms (45) equipped with the actuator (7) on the machine (M) in the configuration of Fig.8.

In relation to what has been described above, a machine for winding web material in the form of reels in accordance with the present invention comprises a winding roller (1) on which the web material intended to be wound passes, in which the winding roller ( 1) cooperates with a winding rod (2) on which the web material is wound to form a reel (B), in which the winding roller (1) is positioned in a structure (3) provided with sides (30) on the which are formed two corresponding linear guides (31) parallel to each other and oriented according to a predetermined direction (L) which defines a direction of advancement of the winding rod (2) while the respective coil (B) is formed on the rod itself, in which the winding roller (1) is oriented transversely to said sides, and in which the machine (M) is served by a magazine (32) in which several winding rods (2) can be stored and by a mechanism for picking up the the rods (2) from the magazine (32), said rod withdrawal mechanism being constituted by a pair of arms (45) each of which is arranged on a corresponding side of the machine and consists of two elements (4, 5) hinged together with the hinge axis (A45) parallel to the rotation axis (1A) of the winding roller (1), an element (5) being hinged on one side of the machine with the hinge axis parallel to the axis (1A) of the winding roller (1) or coinciding with said axis (1A), the other element (4) being provided with gripping means (42) adapted to engage a corresponding end (20) of a rod (2) on the magazine (32 ), and move it towards the winding roller (1) and along a predetermined path (T) with a section parallel to the external surface of the winding roller (1). Said path (T) can comprise a second section parallel to the guides (31).

In a preferred embodiment, the said elements (4, 5) of each arm (45) are each moved by a corresponding actuator (M4, M5).

Preferably, said elements (4, 5) of each arm (45) are constituted by metal plates with prevalent longitudinal development.

In a possible embodiment, an element (5) of each arm (45) is hinged on the machine (M) with the hinge axis coinciding with the axis (1A) of the winding roller (1).

In an alternative embodiment, an element (5) of each arm (45) is hinged on said superstructure with the hinge axis parallel to the axis (1A) of the winding roller (1A.

In a possible embodiment, said gripping means (42) are gripper means with two jaws which, in cooperation with each other, define a gripping seat.

In a possible embodiment, said gripper means comprise a fixed jaw formed on one end of an element (4) of the arm (45) and a movable jaw (420) controlled by an actuator (43). In accordance with this embodiment, the fixed jaw has a concave side (421) facing the movable jaw (420) and the movable jaw (420) has a concave side (422) facing the fixed jaw.

Furthermore, in a possible embodiment of the present invention said arms (45) are controlled by a programmable unit (UE) which receives signals from load cells (C4, C5) mounted on the two elements (4, 5) of each arm and controls the rotation of these elements through corresponding independent actuators (M4, M5). In another embodiment of the present invention, the machine comprises a carriage (6) mounted on each of its sides and provided with gripping means (60) suitable for picking up the rods (2) from said arms (45).

In each of the examples described above, the trajectory of the rods (2) is determined by the rotation of the element (4) around the axis (A45) and by the rotation of the element (5) around the axis of the respective connection hinge with a fixed part of the machine (M) which can be, for example, a side (30) of the latter or a superstructure (32) placed at a greater height of the winding roller (1) with respect to the base on which the machine rests.

In practice, the details of execution may in any case vary in an equivalent manner as regards the individual elements described and illustrated without thereby departing from the technical solution adopted and therefore remaining within the limits of the protection conferred by the present patent in accordance with the attached claims.

Claims (13)

CLAIMS 1) Machine for winding web material in the form of reels, comprising a winding roller (1) on which the web material intended to be wound passes, in which the winding roller (1) cooperates with a winding rod (2 ) on which the web material is wound to form a reel (B), in which the winding roller (1) is positioned in a structure (3) provided with sides (30) on which two corresponding parallel linear guides (31) are formed between them and oriented according to a predetermined direction (L) which defines a direction of advancement of the winding rod (2) while the respective reel (B) is formed on the rod itself, in which the winding roller (1) is oriented transversely to said sides, and in which the machine (M) is served by a warehouse (32) in which several winding rods (2) can be stored and by a mechanism for withdrawing rods (2) from the warehouse (32), characterized by the fact that the said mechanism of pick-up of the rods consists of a pair of arms (45) each of which is arranged on a corresponding side of the machine and consists of two elements (4, 5) hinged together with a hinge axis (A45) parallel to the axis ( 1A) of rotation of the winding roller (1), one element (5) being hinged on one side of the machine with the hinge axis parallel to the axis (1A) of the winding roller (1), the other element (4) being provided of gripping means (42) adapted to engage a corresponding end (20) of a rod (2) on the magazine (32), and move it towards the winding roller (1) and along a predetermined path (T) comprising a parallel section to the outer surface of the winder roller (1). 2) Machine according to claim 1 characterized in that said path (T) comprises a further section parallel to the guides (31). 3) Machine according to claim 1 characterized in that said elements (4, 5) of each arm (45) are each moved by a corresponding actuator (M4, M5). 4) Machine according to claim 1 characterized in that said elements (4, 5) of each arm (45) are constituted by metal plates with prevalently longitudinal development. 5) Machine according to claim 1 characterized by the fact that an element (5) of each arm (45) is hinged on the machine (M) with the hinge axis coinciding with the axis (1A) of the winding roller (1). 6) Machine according to claim 1, in which the magazine (32) of the rods (2) consists of a superstructure of the machine (M) arranged above the winding roller (1), characterized in that an element (5) of each arm (45) is hinged on said superstructure with a hinge axis parallel to the axis (1A) of the winding roller (1). 7) Machine according to claim 1, characterized by the fact that said gripping means (42) are gripper means with two jaws which, in cooperation with each other, define a gripping seat. 8) Machine according to claim 7 characterized in that said gripper means comprise a fixed jaw formed on one end of an element (4) of the arm (45) and a movable jaw (420) controlled by an actuator (43). 9) Machine according to claim 7 characterized in that the fixed jaw has a concave side (421) facing the movable jaw (420) and the movable jaw (420) has a concave side (422) facing the fixed jaw. 10) Machine according to any one of the preceding claims characterized by the fact that said arms (45) are controlled by a programmable unit (UE) which receives signals from load cells (C4, C5) mounted on the two elements (4, 5) of each arm and controls the rotation of these elements through corresponding actuators (M4, M5). 11) Machine according to any one of the preceding claims characterized by the fact that it comprises a trolley (6) mounted on each of its sides and provided with gripping means (60) suitable for picking up the rods (2) from said arms (45). 12) Machine according to claims 1 and 2 characterized in that said movement along the predetermined path (T) is given by the coordinated rotation of said elements (4, 5) around said axes (A45) and (1A). 13) Machine according to any one of the preceding claims characterized in that each of said arms (45) is provided with a rotary actuator (7) adapted to engage a corresponding end (20) of a rod (2) to control its rotation with predetermined angular velocity around the relative longitudinal axis.