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Title:
A UNIT FOR SUPPORTING AND UNWINDING A REEL OF WEB MATERIAL FOR A WEB PROCESSING MACHINE
Document Type and Number:
WIPO Patent Application WO/2012/107906
Kind Code:
A1
Abstract:
The invention relates to a unit (1, 1', V ', 1' ' ' ) for supporting and unwinding a reel (2) of web material having a central through-hole (4); this unit (1, 1', 1", 1" ' ) comprises a support plane (5), provided with a through-hole (8) and adapted to receive and support the reel (2) with its hole (4) coaxial to the hole (8) of the support plane (5); and a releasable fastening device (6) adapted to engage the cited holes (4, 8) and cooperate with the reel (2) to lock it on the support plane (5); one of the support plane (5) and the fastening device (6) is displaceable with respect to the other between the support plane (5) and the fastening device (6) between a first operative configuration, in which the fastening device (6) projects with respect to the support plane (5) on the side where the reel (2) rests, and a second operative configuration, in which the fastening device (6) is contained between the support plane (5) and a side of the support plane (5) opposite to the side where the reel (2) rests.

Inventors:
FERRI MARCO (IT)
ARMONDI SIMONE (IT)
Application Number:
PCT/IB2012/050616
Publication Date:
August 16, 2012
Filing Date:
February 10, 2012
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
SIDEL SPA CON SOCIO UNICO (IT)
FERRI MARCO (IT)
ARMONDI SIMONE (IT)
International Classes:
B65H75/24; B65H19/12
Foreign References:
GB2268144A1994-01-05
EP0994057A12000-04-19
US4861086A1989-08-29
GB2213128A1989-08-09
GB2218779A1989-11-22
Other References:
None
Attorney, Agent or Firm:
JORIO, Paolo et al. (Via Viotti 9, Torino, IT)
Download PDF:
Claims:
CLAIMS

1. A unit (1, 1', 1'', 1' ' ' ) for supporting and unwinding a reel (2) of web material having a central through-hole (4), said unit (1, 1', 1'', 1' ' ' ) comprising:

- a support plane (5) provided with a through-hole (8) and adapted to receive and support said reel (2) with its hole (4) coaxial to the hole (8) of the support plane (5); and

- a releasable fastening device (6) adapted to engage said holes (4, 8) and cooperate with said reel (2) to lock it on said support plane (5) ;

characterised in that one of said support plane (5) and said fastening device (6) is displaceable with respect to the other between said support plane (5) and said fastening device (6) between a first operative configuration, in which said fastening device (6) projects with respect to said support plane (5) on the side where said reel (2) rests, so as to lock the reel (2) on said support plane (5) , and a second operative configuration, in which said fastening device (6) is contained between said support plane (5) and a side of the support plane (5) opposite to the side where the reel (2) rests to allow the loading thereof by sliding along said support plane (5) .

2. The unit according to claim 1, wherein a base element (20, 70) constrained to said support plane (5) is provided, and in which said fastening device (6) comprises locking means (41) borne by said base element (20, 70) and selectively actuatable to interact with said reel (2) and lock it on said support plane (5) .

3. The unit according to claim 2, wherein said base element (20, 70) is rigidly connected to said support plane (5) , and said locking means (41) are movably borne by said base element (20, 70) to define said first and second operative configurations.

4. The unit according to claim 3, wherein said locking means (41) are displaceable with respect to said base element (20) along an axis (A) orthogonal to said support plane (3) to define said first and second operative configurations.

5. The unit according to claim 4, comprising elastic means (63) interposed between said base element (20) and said locking means (41) and loading the locking means (41) towards said first operative configuration.

6. The unit according to any of claims 4 or 5, comprising first engaging means (60, 62) integral with said locking means (41) and second engaging means (30, 35) borne by said base element (20) and couplable with said first engaging means (60, 62) in two different positions along said axis (A) to define said first and second operative configurations .

7. The unit according to any of claims 4 to 6, wherein, in said first operative configuration, said locking means (41) are displaceable between an active position with a maximum radial projection with respect to said axis (A) , in which they are adapted to push on the delimitation surface of the hole (4) of said reel (2) to lock the reel (2) on said support plane (5), and a resting position, radially retracted with respect to the active position, in which they cannot interfere with the delimitation surface of the hole (4) of said reel (2).

8. The unit according to claim 2, wherein said support plane (5) is displaceable with respect to said base element (20) along an axis (A) orthogonal to the support plane (5) to define said first and second operative configurations.

9. The unit according to claim 8, comprising elastic means (36) interposed between said base element (20) and said support plane (5) and loading the support plane (5) towards said second operative configuration.

10. The unit according to any of claims 8 or 9, comprising first engaging means (28, 31, 32, 34) borne by said support plane (5) and second engaging means (30, 32, 35) borne by said base element (20) and couplable with said first engaging means (28, 31, 32) in two different positions along said axis (A) to define said first and second operative configurations.

11. The unit according to claim 3, wherein said locking means (41) comprise at least one pair of hooking levers (71) borne by said base element (70) rotatably about respective hinging axes (B) parallel to said support plane (5) between a lowered position on said base element (70) and within the hole (8) of said support plane (5), in which they define said first operative configuration, and a lifted position, in which they project transversally from said support plane (5) on the side where said reel (2) rests to interact with their hooking ends (72) on the delimitation surface of the hole (4) of the reel (2) .

Description:
"A UNIT FOR SUPPORTING AND UNWINDING A REEL OF WEB MATERIAL FOR A WEB PROCESSING MACHINE"

TECHNICAL FIELD

The present invention relates to a unit for supporting and unwinding a reel of web material adapted to be fed to a web processing machine, such as for example a packaging machine, i.e. a machine capable of folding, sealing and cutting the web material to obtain sealed packs, or a labelling machine, i.e. a machine for obtaining a plurality of labels from the web material and applying such labels to respective articles, typically bottles or containers.

The following description will explicitly refer to the field of labelling machines, without this being intended to limit in any way the scope of protection defined by the claims .

BACKGROUND ART

As is known, labelling machines are used to apply labels on any kind of article, in particular containers. Typically, self-sticking labels are used on milk or juice bottles. These labels are made of a paper/polypropylene/adhesive laminated material.

When the self-sticking labels are applied on the containers, a support web, on which the labels are fixed in reciprocally spaced positions, is unwound from a reel and drawn on a bar or blade so as to achieve the separation of each label from the web itself, which is then discarded. Means are also provided to carry the containers to an application station and to transfer each label to the corresponding container.

In a totally different manner, the web material could be formed by a sequence of adjacent labels which must be sequentially separated from one another by a cutting operation in order to then be applied to the respective containers .

In both cases, the reel of web material is locked on an appropriate unit essentially comprising a support plane for the reel, which is disc-shaped and centrally provided with a threaded shaft, projecting coaxially upwards from the support plane.

The loading of the reel is performed by lifting the reel to a position in which the central hole thereof can be engaged by the threaded shaft and then sliding the reel downwards along the shaft to reach a resting position on the support plane; subsequently, a locking nut is screwed on the threaded shaft from above to lock the reel between the support plane and the nut.

The unwinding of the web material from the reel is obtained by the actuation of an electric motor, arranged on the opposite side of the support plane with respect to the threaded shaft, so as to rotate the plane and the shaft about their axes.

The above disclosed known units have the drawback of requiring a considerable power to lift the reel during the replacement of the reel and to control the descent thereof along the threaded shaft towards the resting position on the support plane.

Furthermore, during the relatively long lifting movement, the reel, which is clamped on the opposite sides of the lifting truck, could be unwound on the inner side taking the shape of a telescope, particularly in the case of the web carrying the self-sticking labels.

DISCLOSURE OF INVENTION

It is an object of the present invention to therefore provide a unit for supporting and unwinding a reel of web material, which allows to overcome in a simple and cost- effective manner the above specified drawbacks related to the units of the known type.

The above said object is achieved by the present invention, as it relates to a unit for supporting and unwinding a reel of web material as defined in claim 1.

BRIEF DESCRIPTION OF THE DRAWINGS Some preferred embodiments are hereinafter disclosed for a better understanding of the present invention, by mere way of non-limitative example and with reference to the accompanying drawings, in which:

- figures 1 and 2 show section views of two different operative configurations, respectively an operation configuration and a loading/unloading configuration, of a unit according to the present invention for supporting and unwinding a reel of web material;

- figures 3 and 4 show perspective views of the unit of figures 1 and 2, respectively in the operative configuration and the loading/unloading configuration;

- figure 5 shows a different perspective view with parts removed for clarity of the unit of figures 1 and 2;

- figures 6 and 7 show top views of two different operative positions, respectively a locked position and a released position, of a fastening device of the reel of the unit of figures 1 and 2;

- figure 8 shows a perspective view of a different embodiment of a unit according to the present invention for supporting and unwinding a reel of web material;

- figures 9 and 10 show section views of two operative configurations, respectively an operation configuration and a loading/unloading configuration, of another embodiment of a unit according to the present invention for supporting and unwinding a reel of web material;

- figures 11 and 12 show perspective views of the unit of figures 1 and 2, respectively in the operative configuration and the loading/unloading configuration;

figure 13 shows a perspective view with parts removed for clarity of a fastening device for the reel forming the unit of figures 9 and 10;

- figure 14 shows a different perspective view on an enlarged scale of a detail of figure 13;

- figure 15 shows a top side view of a detail of figure 14; and

figures 16 and 17 show section views of two operative configurations, respectively an operation configuration and a loading/unloading configuration, of another embodiment of a unit according to the present invention for supporting and unwinding a reel of web material .

BEST MODE FOR CARRYING OUT THE INVENTION

In Figures 1 to 5, numeral 1 indicates as a whole a unit for supporting and unwinding a reel 2 of web material adapted to be fed to a web processing machine (not shown) , such as for example a packaging machine or a labelling machine . Reel 2 is of the type known per se and has an outer cylindrical configuration defined by the web material, which is wound about a core or spool 3 defining a central through-hole 4.

Unit 1 substantially comprises a support plate 5, adapted to receive and support reel 2, and a releasable fastening device 6, adapted to cooperate with reel 2 to lock it on plate 5.

In particular, plate 5 has a discoidal flat configuration and is provided centrally with a through-hole 8, having an axis A orthogonal to plate 5.

As may be seen in figures 3 and 4, plate 5 is borne by a frame 9 (only partially shown) which is fixed in a horizontal position and rotates about axis A.

Plate 5 is adapted to receive reel 2 on a top surface

10 thereof with hole 4 thereof coaxial to hole 8 of plate 5.

Fastening device 6 extends coaxially to axis A and is adapted to engage both holes 4 and 8 to lock reel 2 on plate 5.

Unit 1 also comprises an electric motor 11 arranged below plate 5 and selectively activatable to rotate plate 7 and fastening device 6 about axis A so as to unwind the web material from reel 2. As may be seen in figures 3 and 4, motor 11 projects below a wall 12 of frame 9, which extends in turn parallel to a lower position with respect to plate 5. Motor 11 is supported by wall 12 coaxially to plate 5 and to fastening device 6.

In greater detail, motor 11 comprises a stator 13 fixed to wall 12, and an outlet member 15 (only partially visible in figures 1 and 2) supported by stator 13 rotatably about axis A and engaging a through-hole of wall 12.

Advantageously, plate 5 is displaceable in a direction parallel to axis A with respect to fastening device 6 to define a first and a second operative configuration, respectively an operation configuration and a loading/unloading configuration: in the first operative configuration, fastening device 6 protrudes with respect to plate 5 on the side where reel 2 rests so as to lock reel 2 on plate 5; in the second operative configuration, fastening device 6 is contained between plate 5 and a side thereof opposite to the side where reel 2 rests to allow the loading and unloading of reel 2 by sliding along plate 5.

With reference to figures from 1 to 5, fastening device 6 is borne on top by a base element 20 constrained to plate 5 on the side opposite to the receiving side of reel 2 and coupled to outlet member 15 of motor 11.

In particular, base element 20 substantially has a cup-shaped configuration and defines an inner cavity 21 facing plate 5. Base element 20 comprises a bottom discoidal wall 22 parallel to plate 5, a side annular cylindrical wall 23 projecting above from the periphery of bottom wall 22, and an annular flange 24 projecting radially outwards from a top edge of side wall 23 and extending parallelly to bottom wall 22 and to plate 5.

Bottom wall 22 of base element 20 also has a central through-hole 25 having axis A engaged by a corresponding portion of outlet member 15 and fixed thereto by means of a plurality of screws 26.

Base element 20 and fastening device 6 therewith are also connected to plate 5 by means of releasable constraint means 27 defining the cited first and second operative configurations .

In particular, constraint means 27 comprise a plurality of engaging elements 28 fixed orthogonally protruding to a lower surface 29 of plate 5 in positions angularly equally spaced about axis A, and each couplable to flange 24 of base element 20 in two different axial positions in a direction parallel to axis A so as to define the first and the second operative configuration of plate 5 with respect to fastening device 6.

Constraint means 27 also comprise a plurality of fastening members 30 protruding from flange 24 of base element 20 in angularly equally spaced positions about axis A and each couplable with a corresponding engaging element 28 to define the first operative configuration.

More precisely, each engaging element 28 is defined by a cylindrical upright 31 having an axis parallel to axis A, projecting orthogonally from lower surface 29 of plate 5 and slidingly engaging a relative through-hole 32 obtained in flange 24 of base element 20; each upright 31 is also provided in an intermediate position along its side surface, with an engaging through-hole 33 for relative fastening member 30, extending radially with respect to the axis of upright 31.

Each upright 31 is finally provided, at its lower end, with a cylindrical pin 34 projecting laterally on diametrically opposite sides of upright 31 and adapted to prevent the axial sliding off thereof from relative hole 32 of flange 24 of base element 20.

Fastening members 30 are instead protrudingly fastened to a lower surface of flange 24 of base element 20 near relative holes 32. As may be seen in particular in figure 5, fastening members 30 comprise one or two constraint elements 35 which are mobile in a radial direction with respect to the axis of relative upright 31 between an engaging position in hole 33 of upright 31 and a released position therefrom.

Constraint means 27 also comprise a plurality of cylindrical helix springs 36 wound about respective uprights 31, interposed between flange 24 of base element 20 and plate 5 and loading plate 5 towards the second operative configuration.

Holes 33 of uprights 31, when engaged by relative constraint elements 35 of fastening members 30, define the cited first operative configuration, in which plate 5 is at a minimum axial distance from flange 24 of base element 20 in a direction parallel to axis A and springs 36 are in a strongly compressed condition.

Differently, the interaction between pins 34 of uprights 31 and the lower edge of respective holes 32 of flange 24 of base element 20 defined the cited second operative configuration, in which plate 5 is at a maximum axial distance from flange 24 in a direction parallel to axis A and springs 36 are in a more extended condition with respect to the previous case.

With reference to figures 1 to 7, fastening device 6 essentially comprises a support plate 40 having a discoidal structure with axis A, protruding from bottom wall 22 of base element 24 in a position parallel to bottom wall 22 and plate 5, and locking means 41 borne by plate 40 and selectively actuatable to interact with spool 3 of reel 2 and lock it on plate 5.

In particular, plate 40 is rigidly connected to bottom wall 22 of base element 20 by means of a plurality of uprights 42 extending parallelly to axis A within cavity 21 and is adapted to coaxially engage hole 8 of plate 5 in the first operative configuration.

Locking means 41 protrude from plate 40, on the opposite side to the connection side of plate 40 to bottom wall 22 by means of uprights 42, and are selectively displaceable with respect to base element 20 between an active position (figure 7) with a maximum radial projection with respect to axis A, in which they are adapted to push on the delimitation surface of hole 4 of reel 2 to lock reel 2 on plate 5, and a resting position (figure 6) radially retracted with respect to the active position, in which they cannot interfere with the delimitation surface of hole 4 of reel 2.

In the case shown, locking means 41 comprise a pair of curvilinear profiled claws 43, which extend substantially across two halves of plate 40 and are hinged to plate 40 at one (44) of the ends thereof and by means of respective pins 45 arranged on diametrically opposite sides of axis A and extending parallel thereto.

In particular, each claw 43 has a convex arched edge 46, adjacent to the periphery of plate 40, a radially internal concave edge 47 which is also arched and faces axis A, and a distal end 48 arranged adjacent to hinging end 44 of other claw 43.

In the active position, convex edges 46 of claws 43 project externally with respect to the profile of plate 40 so as to cooperate with the delimitation surface of hole 4 of reel 2; in the resting position, convex edges 46 of claws 43 are instead contained within the periphery of plate 40 and cannot interact with the delimitation surface of hole 4 of reel 2.

Locking means 41 further comprise a control member 50 which is manually actuated to determine, in the first operative configuration, the simultaneous rotation in opposite directions of claws 43 about respective pins 45 between the active and resting positions (figures 6 and 7).

In particular, control member 50 (figures 1 to 7) comprises a push lever 51 having an elongated profile, hinged on plate 40 by means of a central pin 52 having axis A and cooperating, at its opposite ends, with concave inner edges 47 of claws 43 so as to determine, by its rotation about axis A, the simultaneous rotation of claws 43 in opposite directions about respective pins 45.

In particular, pin 52 is angularly integral to push lever 51 and is mounted rotatably about axis A in a through-hole of plate 40.

Control member 50 further comprises an actuating lever

54 fixed radially to pin 52, arranged on the opposite side of plate 40 with respect to push lever 51 and projecting outwards of base element 20 through a slot 55 obtained on side wall 23 of base element 20.

As may be seen from figures 1 and 3, in the first operative configuration, fastening device 6 engages with its plate 40 hole 8 of plate 5 and projects above the latter with its claws 43, which can therefore be displaced between the active and resting positions.

With reference instead to figures 2 and 4, in the second operative configuration, claws 43 of fastening device 6 engage hole 8 of plate 5 and do not project above the latter.

In use, the replacement of the reel is performed as follows .

First, spool 3 of finished reel 2 must be removed from unit 1; in order to perform this operation, claws 43 must be displaced from the active position (figure 7), in which they radially push on the delimitation surface of hole 8 of spool 3, to the resting position (figure 6) .

With reference to figures 6 and 7, the displacement of claws 43 to the resting position is obtained by a clockwise rotation of push lever 51 so as to determine a sort of "closure" of claws 43 inwards of the profile of plate 40 and towards axis A; this closure operation is aided by the presence of springs (not visible in the accompanying figures) loading claws 43 towards the resting position.

The rotation of push lever 51 is performed by a corresponding manual rotation of actuating lever 54 within slot 55 of side wall 23 of base element 20.

In this condition, spool 3 of finished reel 2 can be removed from unit 1.

At this point, plate 5 must be displaced so as to pass from the first to the second operative configuration (figures from 1 to 4). This operation could be carried out before removing spool 3 of finished reel 2 and is performed releasing fastening members 30 from holes 33 of constraint elements 28; thereby, plate 5 is pushed in a direction parallel to axis A by the action of springs 36 until the second operative configuration is obtained, defined by the interaction between pins 34 and the lower edge of holes 32 of bottom wall 2 of base element 20.

In this configuration, a new reel 2 can be loaded on plate 5 and horizontally slid along the latter until the position is reached in which it is arranged coaxially to axis A with its hole 4 in communication with hole 8 of plate 5.

Displacing plate 5 again so as to approach it to base element 20 and press springs 36, claws 43 of fastening device 6 are engaged within hole 4 of reel 2; once hole 33 of engaging elements 28 are arranged facing respective fastening members 30, the displacement thereof in holes 33 fixes plate 5 in the new position and obtains the first operative configuration.

At this point, by actuating actuating lever 54, push lever 51 can be rotated counterclockwise about axis A with the subsequent "opening" movement of claws 43 which reach their active position, in which they push on the delimitation surface of hole 4 of reel 2 locking reel 2 on plate 5 (figure 7) .

By actuating motor 11, outlet member 15 rotates base element 20, and fastening device 6 and plate 5 through base element 20, about axis A, so as to obtain the unwinding of reel 2. In figure 8, numeral 1 indicates as a whole a different embodiment of a unit according to the present invention for supporting and unwinding reels 2 of web material; unit 1' will be disclosed hereinafter only as far as it differs from unit 1, using, where possible, the same reference numerals for equivalent parts or parts corresponding to already disclosed parts.

In particular, unit 1' differs from unit 1 essentially in its configuration of locking means 41, which in this case comprise a plurality of claws 43' configured as prismatic blocks and borne by plate 40 in positions angularly equally spaced about axis A; each claw 43' may be radially displaced with respect to axis A between a resting position, in which it is radially spaced from the periphery of plate 40, and an active position, in which it projects radially from plate 40 so as to interact with the delimitation surface of hole 4 of reel 2.

In figure 9 to 12, numeral 1'' indicates as a whole a different embodiment of a unit according to the present invention for supporting and unwinding reels 2 of web material; unit 1'' will be disclosed hereinafter only as far as it differs from unit 1, using, where possible, the same reference numerals for equivalent parts or parts corresponding to already disclosed parts. In particular, unit 1' ' differs from unit 1 essentially in that plate 5 is rigidly constrained to base element 20 by means of fixed uprights 31, and in that locking means 41 are borne in a mobile manner by base element 20; in particular, in the case shown, locking means 41 may be displaced with respect to base element 20 not only to define the active and resting positions but also along axis A to define the above mentioned first and second operative configuration.

More precisely, in this case, plate 40 which bears locking means 41 is in turn fixed on top by a substantially cylindrical intermediate element 60 having axis A, mounted in an axially sliding manner in cavity 21 of base element 20.

Intermediate element 60 is defined by a hollow cylinder having, along its side wall 61 and on diametrically opposite parts of axis A, respective pairs of holes 62; in particular, holes 62 of each pair are placed at different axial heights and are adapted to be alternatively engaged by a constraint element 35 of a relative fastening member 30, borne on top by flange 24 of base element 20, to define the cited first and second operative configurations.

A cylindrical helical spring 63 is also interposed between intermediate element 60 and bottom wall 22 of base element 20; spring 63 is adapted to load intermediate element 60 together with plate 40 and its locking means 41, towards the first operative configuration, defined by the engagement of constraint elements 35 of fastening members 30 in holes 62 of intermediate element 60 placed in the position nearest to spring 63.

As may be seen in figures 9 to 15, unit 1' ' also differs from unit 1 in that locking means 41 have in this case no actuating lever 54; the handling of push lever 51 is therefore performed for example by means of a hex key (known per se and not shown) to be inserted in a complementary hole 64 obtained in pin 52.

The locking of push lever 51 in two angular position in which it maintains claws 43 respectively in the active position and in the resting position is obtained by a cam 65 fixed to pin 52 and interacting with a relative striker element 66 borne by plate 40.

In greater detail, cam 65 (figures 14 and 15) extends within intermediate element 60 on the opposite side of plate 40 with respect to locking means 41 and has a truncated disc configuration which is thicker, in a direction parallel to axis A, at the truncated side than at the diametrically opposite side. Striking element 66 is formed by an L bracket fixed to plate 40 on the side opposite to that from which locking means 41 extend and arranged on one side of axis A; striking element 66 defines with plate 40 an engaging seat 67 for the peripheral portion of cam 65, so that, at the two angular positions of push lever 51 which define the active and resting positions of claws 43, the thickest area of cam 65 is interference fitted in seat 67 between plate 40 and striking element 66, while in the other angular positions of push lever 51, cam 65 can freely slide between plate 40 and striking element 66.

In the case of unit 1' ' , the replacement of the reel takes place similarly to unit 1, with the following differences :

- the displacement of claws 43 between the active and resting positions takes place by means of a hex key to be inserted in hole 64 of pin 52; and

- the passages between the first and second operative configuration take place by means of the displacement along axis A of intermediate element 60 and therefore of plate 40 and of locking means 41, with respect to plate 5 and base element 20.

In figure 16 and 17, numeral 1''' indicates as a whole a different embodiment of a unit according to the present invention for supporting and unwinding reels 2 of web material; unit 1' ' ' will be disclosed hereinafter only as far as it differs from unit 1, using, where possible, the same reference numerals for equivalent parts or parts corresponding to already disclosed parts.

In particular, unit 1' ' ' differs from unit 1 essentially in that base element 20 is defined by a plate 70 rigidly fixed to plate 5 and outlet member 15 of motor 11 in a coaxial position of axis A, and in that locking means 41 are directly borne by plate 70 on the side opposite to the fastening side to outlet member 15.

More precisely, plate 70 is fixed to plate 5 so as to cover hole 8 on the side opposite to that intended to receive reel 2.

Furthermore, in this case, locking means 41 comprise at least one pair of hooking levers 71, engaging hole 8 of plate 5 and borne by plate 70 rotatably about respective hinging axes B parallel to plate 5 and orthogonal to axis A.

Hooking levers 71 are rotatable about axes B between a lowered resting position, defining the cited second operative configuration, and a lifted interaction position with reel 2, defining the cited first operative configuration . In particular, in the lowered resting position, hooking levers 71 lie on plate 70 and within hole 8 of plate 5 so as not to project above with respect to plate 5; in the lifted position, instead, hooking levers 71 project transversally from plate 5 on the resting side of reel 2 to interact, by means of hooking ends 72 thereof, with the delimitation surface of hole 4 of reel 2.

In the case of unit 1' ' ' , the replacement of reel takes place similarly to units 1, 1', 1'' with the only difference that the passages between the first and the second operative configuration take place by means of simple rotations of hooking levers 71 between the lowered position and the lifted position.

From an analysis of the features of units 1, 1', 1' ' and 1' ' ' made according to the present invention, the advantages it allows to obtain are apparent.

In particular, in virtue of the possibility to act on support plate 5 or on fastening device 6 to bring the latter in a condition in which it is placed below support plate 5 and therefore does not project therefrom, the operation of replacing the reel results considerably simplified and requires reduced power and effort with respect to the known solutions.

Indeed, the lifting movement of reel 2 during the operation of replacement of the reel is minimised, as reel 2 only needs to be lifted to support plate 5.

Furthermore, minimising the lifting movement allows of course to also minimise the risks that, during this movement, the reel can unwind on the inner side taking the shape of a telescope.

Finally, it should be noted that the disclosed units allow the loading and unloading of reel 2 in a particularly convenient manner without requiring the disassembly and subsequent reassembly of components.

Finally, it is apparent that modifications and variants may be made to units 1, 1', 1'' and 1' ' ' disclosed and shown herein without because of this departing from the scope of protection defined by the claims.

In particular, the operation of locking means 41 could be automatic.

Furthermore, electric motor 11 could also be avoided.