The present invention relates to a winding machine (100) suitable for using specific expandable spindles capable of defining a lying surface for a core of a spool to be produced by the rotation of the spindle around itself, which allows said lying surface to be varied in a rapid and versatile manner on the basis of the dimensions of said core.

Winding machines are currently used for producing spools, in particular comprising a flexible plastic film, comprising a support on which a plurality of spindles are assembled on which the cores are fitted, around which the spools are wound by the rotation of the spools around themselves.

In particular, these machines are suitable for operating in continuous and for this purpose the support holding the spindles is rotating so that each spindle can be in a winding position, in a spool discharging position and in a core loading position. In this way, while a spool is being formed around the spindle which is in a winding position, a new core is inserted around the spindle in a core loading position and the spool previously formed around the spindle, which is in a discharging position, is removed from the machine. Current winding machines for flexible film and particularly for stretch film, have the disadvantage of not being able to manage the various types of spools to be produced with a single apparatus, due to the significant difference of the final products, in terms of weight and size of the spool.

In all types of known winding machines, there is still the limit of format changes and the considerable economic losses associated with the same. Format change operations can be aimed, for example, at passing from spindles suitable for 2 " cores, about 5 cm in diameter, to spindles suitable for 3" cores, about 7.5 cm in diameter .

The operations to be effected, even in the most advanced winding machines, consist in dismantling the spindles having a diameter size and reassembling a different series of spindles having a different diameter. In addition to this operation, other complementary operations must be effected for guaranteeing the correct loading of the cartons, the correct cutting of the film, the correct discharging of the spools produced.

All of these operations must be effected by experienced and properly trained operators, with a consequent stoppage of the line for the time necessary for the above operations.

In addition to this, due to the particular production, a certain quantity of waste must be considered before being able to re-produce marketable film. Ultimately therefore there are two types of economic losses deriving from format-change operations: the first type derives from the non-production time of the machine (during the stoppage and during the production of waste) , the second derives from the costs of the material, electric energy and labour during the production of said waste.

The objective of the present invention is to develop a winding machine suitable for using a series of specific spindles of the expandable type, which allows the dimension of the lying surface defined by the spindle itself and destined for receiving the spool core, to be rapidly regulated.

This objective is achieved by means of a spindle for the winding of spools defining a lying surface suitable for receiving a core of a spool, said lying surface being at least partly arranged around a development axis of said spindle and at least partly orthogonal to a transversal radial direction with respect to said development axis, characterized in that it comprises a plurality of caps translating radially with respect to said development axis and actuation means suitable for varying the radial position of said caps and suitable for creating, for each radial position of said caps and in correspondence with said lying surface, a radial pressure on the part of said caps on said core, so that said core follows a rotation of said spindle around said development axis.

A possible embodiment of the present invention can provide at least one of the following aspects.

The actuation means preferably comprise a plurality of supports respectively constrained to said caps and translating radially together with the same.

The supports preferably comprise respective distal ends with respect to said development axis and respective proximal ends with respect to said development axis, said caps being respectively constrained to said supports in correspondence with said distal ends. In this way, the supports can effectively press the respective caps against the inner surface of the spool core.

The supports also preferably comprise respective intermediate portions that connect the respective distal ends with the respective proximal ends.

The spindle preferably comprises a central structure through which said supports can translate radially .

The central structure serves to guide the translation of the caps along the radial direction with respect to the development axis of the spindle, and preferably also exerts a structural function.

The central structure preferably comprises cavities suitable for the respective sliding of the supports, and in particular suitable for respectively receiving the respective intermediate portions of said supports.

The supports preferably respectively comprise, in correspondence with said proximal ends, a plurality of stoppage means suitable for opposing said central structure in a configuration of maximum distancing of said supports from said development axis.

In this way, the supports are prevented from exiting from the central structure.

The stoppage means also preferably respectively comprise various expansions that respectively have a plurality of opposing surfaces suitable for respectively blocking the radial translation of said supports moving away from said development axis. The actuation means preferably comprise pushing means, preferably comprising a pneumatic or hydropneumatic system, suitable for causing the radial translation of said caps and radial pressure on the part of said caps on said core.

The pushing means preferably act on said supports to cause the radial translation of said caps and said radial pressure on the part of the caps on said core.

The pushing means preferably comprise at least one actuator of the pneumatic or electromechanical type.

The supports preferably have a variable length along said radial direction.

This increases the variation which can be imparted to the lying surface defined by the spindle, for receiving cores having variable dimensions.

The actuation means preferably comprise at least one actuator capable of varying the length of said supports along said radial direction, said actuator preferably being of the pneumatic or electromechanical type .

The caps respectively comprise respective pushing surfaces configured for exerting a tangential entrainment action on various parts of said core respectively, so as to entrain it during the rotation of said spindle around its own development axis.

According to a further aspect, the present invention relates to a winding machine suitable for producing different types of spools on cores having different diameters, respectively, comprising various spindles that have at least one of the previous characteristics .

Said machine preferably comprises a control unit capable of varying the force exerted by said actuation means on said caps and/or the radial position of said caps and/or the pressure exerted by said caps on said core .

The characteristics of the present invention will appear more evident from the following detailed description, provided for illustrative and non-limiting purposes of what is more generally claimed.

The following detailed description refers to the enclosed drawings, in which:

figure 1 is a perspective view of the preferred embodiment of the present invention;

figure 2 is a sectional view of said embodiment, according to the line A-A of figure la;

figure 3 is a view according to the section A-A of figure la, with a core fitted on the spindle;

- figure 4 is a second view according to the section A-A of figure la, with a core having a larger diameter with respect to that of figure 3 fitted on the spindle; figures 5a-5f are plan views of a winding machine comprising spindles according to the present invention, in correspondence with various operational phases, respectively .

Figure 1 shows a spindle 1 for winding spools defining a lying surface suitable for receiving a core of a spool. The lying surface is at least partly arranged around a development axis X of the spindle 1 and at least partly orthogonally to a transversal radial direction R with respect to said development axis X. As also shown in figures 1-4, the spindle 1 comprises a plurality of caps 2 translating radially with respect to said development axis X. The spindle 1 also comprises actuation means suitable for varying the radial position of said caps 2 and suitable for creating, for each radial position of said caps 2 and in correspondence with said lying surface, a radial pressure on the part of said caps 2 on the spool core.

Said radial pressure is exerted practically in a radial direction and towards the outside of the spindle .

The caps 2 are practically shells suitable for defining the lying surface, and in jargon are defined as tiles, in particular according to the form acquired in the embodiment shown, as can be observed in figure 1.

The spindle 1 is suitable for receiving cores having different diameters, thanks to the possibility of varying the dimension of the lying surface defined by the spindle 1 itself. Figures 3 and 4 show two types of cores A' and A" respectively, which are respectively fitted on the spindle 1 in correspondence with two different operational positions of the caps 2.

The caps 2 are suitable for ensuring that the core A' or A" follows the rotation of said spindle 1 around its development axis X, which in figures 2-4 is identified with a dot as it is orthogonal to the plane of said figures.

In figures 2-4 some components are indicated and/or shown only in some of said figures for the sake of clarity .

The caps 2 respectively comprise respective pushing surfaces 2a configured for exerting a tangential entrainment action on various parts of said core A' or A" respectively, so as to entrain it during the rotation of said spindle 1 around its development axis X. The pushing surfaces 2a are therefore at least partly suitable for producing a certain friction on the core A' or A", also on the basis of the pressure exerted by the same on said core A' or A".

The surfaces 2a can, for example, be suitably treated by means of ribbing or knurling, in order to increase their roughness. The actuation means advantageously comprise a plurality of supports 3 respectively constrained to said caps 2 and translating radially together with the same. The radial direction is defined with two axes identified as R in figures 2 and 4, and can coincide with any of the transversal axes with respect to the development axis X and lying on the plane of figures 2-4.

The supports 3, that practically act as a support for the caps 2, comprise respective distal ends 3a with respect to said development axis X, and respective proximal ends 3b with respect to said development axis X. The caps 2 are advantageously constrained respectively to said supports 3 in correspondence with said distal ends 3a.

In this embodiment, the supports 3 comprise respective intermediate portions that connect the distal ends 3c with the proximal ends 3b, respectively.

In order to guide the movement of the caps 2, the spindle 1 comprises a central structure 4 through which said supports 3 can translate radially. The supports 3 respectively comprise, in correspondence with said proximal ends 3b, a plurality of stoppage means 5 suitable for opposing said central structure 4 in a condition of maximum distancing of said supports 3 from said development axis X.

The supports 3 can in fact advantageously acquire a condition of maximum proximity to the development axis X, for example coinciding with the situation of figure 2 and figure 3, and a condition of maximum distancing from the same, coinciding for example with the situation of figure 4.

The stoppage means 5 respectively comprise various expansions that respectively represent various opposing surfaces 5a suitable for blocking the radial translation, as a stop for the maximum expansion possible, of said supports 3 respectively, away from said development axis X.

The central structure 4 preferably comprises cavities 4a suitable for the sliding of the supports 3, and in particular suitable for respectively receiving the intermediate portions 3c of the supports 3.

The actuation means, not shown, preferably comprise pushing means, preferably comprising a pneumatic or hydropneumatic system, suitable for causing the radial translation of said caps 2. The pushing means are preferably suitable for also creating the radial pressure that the caps 2 exert on the core A' or A".

The pushing means can comprise at least one pneumatic or electromechanical actuator. The pushing means are preferably situated in the central area of the spindle 1, and are therefore advantageously interposed between the various supports 3.

The pushing means act on said supports 3 to cause the radial translation of said caps 2 and the radial pressure on the part of said caps 2 on said core A' or A".

As can be observed on comparing figures 3 and 4, the supports 3 have a variable length along the radial direction R. In figure 4, in fact, the supports 3, in addition to having the proximal end 3b further away from the development axis X, with respect to figure 3, also have a greater length. The intermediate portion 3c of the various supports 3 is in fact larger in figure 4 with respect to the situation of figure 3.

For this purpose, in fact, according to an embodiment, the supports 3 are preferably at least partly of the telescopic type. Again, in order to vary the extension of the supports 3 along the radial direction R, the actuation means preferably comprise at least one actuator capable of varying the length of said supports 3 along said radial direction R. Said actuator is preferably pneumatic or electromechanical.

Figures 5a-5d show a winding machine 100 suitable for producing different types of spools on respective cores having different diameters. In figures 5a-5d, the machine 100 is producing spools B" around cores A" of the type shown in figure 4.

Analogously, the winding machine 100 can produce spools B' wound around cores A' having smaller dimensions with respect to the cores A".

The winding machine comprises various spindles Ml, M2, M3, M4 that have one or more of the above characteristics.

The machine 100 advantageously comprises a control unit capable of varying the force exerted by said actuation means on said caps 2 and/or the radial position of said caps 2 and/or the pressure exerted by said caps 2 on said cores A', A".

In figure 5a, the spindle Ml is in a winding position P2 and a new spool B", shown and indicated in figure 5b once completed, is about to be wound around the same spindle Ml. The machine 100 advantageously comprises a contact group 40, which keeps the material of the spool pressed while the same is being wound, as shown in figures 5a and 5b.

In figure 5a, a spool B" completed and wound around the spindle M2 is in a discharging position P3, ready to be removed from the machine 100. Furthermore, the machine 100 shown in the figures, comprises an accompanying group 60 which serves to keep the material of the spool B" stretched and pressed, while the spindle Ml on which the spool B" is being wound, is moving from a winding position P2 to a discharging position P3, as shown in figures 5c and 5d.

In figure 5e, the spindle M4 itself has reached a winding position P2, whereas the spool B" wound around the spindle Ml is in a discharging position P3. Before a new spool begins to be wound around the spindle M4, a cutting group 50 cuts the material interposed between the spindle Ml and the spindle M4, as can be seen in figure 5f.

While the cutting group 50 is effecting the cutting, the contact group 40 cooperates with the accompanying group 60 to hold the material of the spool B" that is interposed between the spool B" itself and the spindle M4. The portion of material that is cut is not shown for the sake of clarity of the figures.

Even just before the situation shown in figure 5a, the portion of material interposed between the spool B" and the spindle Ml has been cut by the cutting group 50.

Furthermore, the spindles can also be positioned in the core-loading position PI, in correspondence with which a new core is loaded onto the spindle which is in this position for the winding of a future spool when the same spindle is in a winding position P2.

In order to allow the spindles to move between the positions PI, P2 and P3, the machine 100 preferably comprises a rotating plate 14.

The invention achieves the objectives proposed and allows the use of a single expandable spindle 1 for cores having different diameters and therefore for spools having different sizes and weights, without having to replace the spindles of the winding machine, and therefore without having to stop the production.