WO2010026604A1

WO2010026604A1 - Method and machine for the production of reels of film material

Info

Publication number: WO2010026604A1
Application number: PCT/IT2008/000569
Authority: WO
Inventors: Fulvio Porzio
Original assignee: Saiet S.R.L.
Priority date: 2008-09-05
Filing date: 2008-09-05
Publication date: 2010-03-11

Abstract

Described herein is a method for producing reels (2) of film material having a first thickness (3b) starting from a film material having a second thickness (3a) greater than the first thickness, comprising the steps of : stretching the film material having the second thickness (3a) so as to obtain the film material having the first thickness (3b); forming a reel (2) of material having the first thickness (3b); and executing an operation of cutting on the film material having the first thickness (3b) so as to separate the reel (2) from the remaining part of the film material having the first thickness (3b); the step of forming the reel (2) comprises the steps of winding a first end portion (Pl) of the film material having the first thickness (3b) on a first spindle (21; 26) and displacing, during the winding step, the first spindle (21; 26) into a first position (Q); the step of executing the cutting operation comprises the steps of supporting a second portion (P2) of the film material having the first thickness (3b) on a second spindle (26; 21) set in a second position (R) and cutting a section (S) of the film material having the first thickness (3b) set between the first and second portions (Pl, P2) •

Description

"METHOD AND MACHINE FOR THE PRODUCTION OF REELS OF FILM MATERIAL"

TECHNICAL FIELD The present invention relates to a method and machine for the production of reels of film material, in particular a pre- stretched film material that is designed to be used to provide industrial packaging.

BACKGROUND ART

Machines for the production of reels of a film material are known that basically comprise a feed station, in which a film material having a first thickness is wound off a first reel, one or more stretching stations, in which the film material is stretched until a second thickness smaller than the first is reached, and a terminal station, in which the film material having the second thickness is wound onto a second reel.

In greater detail, machines of a known type comprise a plurality of conveying rollers, which define a path of advance from the feed station to the terminal station.

The stretching station basically comprises a first roller, on which the film material having the first thickness is wound, and a second roller, from which the film material having the second thickness is unwound.

The first and second rollers are able to rotate in the same direction at respective angular velocities different from one another and delimit on opposite sides a compartment traversed by the material .

More precisely, when the film material having the first thickness traverses the aforesaid compartment, it co-operates, on opposite sides thereof, with the first roller which is able to rotate at a lower angular velocity and with the second roller which is able to rotate at a higher velocity. Thanks to this difference of angular velocity, the film material is stretched, i.e., it is reduced in thickness and increased in length.

Machines of a known type further comprise a station for cutting the second reel of stretched film material, which is set downstream of the stretching station and upstream of the terminal station.

Said cutting station is provided for separating the second reel of film material having the second thickness from the remaining part of the film material.

There is felt in the sector the need to carry out the operation of cutting of the film material without stopping and/or slowing down the film material itself so as to not penalize the rate of output of the machine for production of the second reels .

DISCLOSURE OF INVENTION

The aim of the present invention is to provide a method for the production of reels of pre-stretched film material that will enable the aforesaid need to be met in a simple and inexpensive way.

The above aim is achieved by a method for the production of reels of film material having a first thickness starting from a film material having a second thickness greater than the first thickness, according to what is defined in Claim 1.

The present invention also relates to a machine for the production of reels of film material having a first thickness starting from a film material having a second thickness greater than the first thickness, according to what is defined in Claim 9. BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, a preferred embodiment thereof is described in what follows, purely by way of non-limiting example and with reference to the attached drawings, wherein:

- Figure 1 is a schematic illustration of a machine for the production of reels of film material having a first thickness starting from a film material having a second thickness greater than the first, built according to the present invention;

- Figure 2 is a front view at a markedly enlarged scale of a unit for forming and a unit for cutting reels of film material incorporated in the machine of Figure 1 ;

- Figures 3 to 10 illustrate respective successive steps of an operation for forming and cutting a reel of film material performed in the machine of Figure 1 ;

- Figures 11 and 12 illustrate at an enlarged scale two different operative positions of the cutting unit of Figure 2 reached in respective intermediate steps between the steps illustrated in Figures 7 and 8 ;

- Figures 13 and 14 illustrate at a markedly enlarged scale some details of the cutting unit of Figures 2, 11 and 12;

- Figure 15 illustrates in side view a further detail of the cutting unit of Figures 2, 13 and 14; - Figure 16 and 17 illustrate in top plan view and lateral perspective view, respectively, some details of the forming unit of Figure 2 ; and

- Figure 18 illustrates in top plan view further details of the forming unit of Figures 2, 16 and 17.

BEST MODE FOR CARRYING OUT THE INVENTION

With reference to Figure 1, designated by 1 is a machine for the production of reels 2 (one of which is visible in Figures 2 to 10) of a film material 3b having a first thickness, starting from a film material 3a having a second thickness, greater than the first thickness. For reasons of simplicity, the film material 3a, 3b will be referred to in the sequel of the present description as film 3a, 3b.

In extreme synthesis, the machine 1 basically comprises:

- a feed station 4, in which the film 3a is wound off a reel 5;

- a plurality of first rollers 6, which can turn about respective axes parallel to one another and set so as to convey the film 3a along a path lying in a plane orthogonal to the axes of the first rollers 6 ;

- a stretching station 7, in which the film 3a is brought to a second thickness smaller than the first thickness and from a first length to a second length greater than the first so as to obtain the film 3b;

- a plurality of second rollers 6, which can turn about respective axes parallel to one another and set so as to convey the film 3b along a path lying in a plane orthogonal to the axes of the second rollers 6 themselves;

- a forming unit 8, in which the reels 2 are formed in sequence ;

- a cutting unit 9 (visible in Figures 2 and 7 to 14) , in which each reel 2 is separated from the remaining part of the film material; and

- a fork 10 (Figures 2, 10 and 16) for picking up the reels 2.

In greater detail, the stretching station 7 comprises a pair of rollers 11, 12, which can turn in the same direction with angular velocities different from one another and co-operate simultaneously with the advancing film 3a.

In greater detail, the film 3a is wound partially on the roller 11 and traverses a compartment defined on opposite sides by the rollers 11, 12 in which it is stretched and brought from the first thickness to the second thickness. Then, the film 3b abandons the roller 12.

Advantageously, the forming unit 8 comprises (Figures 2 to 10) :

- a spindle 21, which can be displaced into a position Q (Figures 7 to 9) ;

- a roller 20, which is designed to wind an end portion Pl of the film 3b on the spindle 21 and can be displaced fixedly with respect to the spindle 21 into the position Q;

- a spindle 26, which can be displaced into a position R (Figures 7 to 10) , distinct from the position Q; and

- a roller 25, interacting with the spindle 26, set in the position R for supporting a portion P2 of the film 3b; the cutting unit 9 further comprises a cutting element 90, which can be displaced into a cutting position (Figures 9 and 14) for cutting a section S of the film 3b set between the portions P^, P2 when the spindles 21, 26 are respectively in the positions Q, R.

In particular, the positions Q, R are indicated in Figures 7 to 9, 12 and 14 via the projections of the axes B, D of the corresponding spindles 21, 26 in a direction T, which in use is horizontal.

As will be clear from the sequel of the present description, the machine 1 describes a plurality of alternating cycles of forming and cutting of the reels 2.

During each cycle of forming of one of the reels 2, the portion P^ is wound onto the spindle 21 (or 26) , the spindle 21 (or 26) is displaced into the position Q fixedly with respect to the portion Pi being wound, and the other spindle 26 (or 21) is displaced into the position R and supports the portion P2. The reel 2 is then cut from the remaining part of the film 3b and, during the subsequent forming cycle, the new portion P^ of the remaining part of the film 3b is wound on the spindle 26 (or 21) , the spindle 26 (or 21) is displaced into the position Q fixedly with respect to the new portion P^ being wound, the other spindle 21 (or 26) is displaced into the position R and supports the portion P2 of the remaining part of the film 3b.

The rollers 20, 25 are made of elastomeric material.

The spindles 21, 26 are made of metal material with a surface treatment designed to facilitate extraction of the reel 2 at the end of winding.

The rollers 20, 25 and the spindles 21, 26 extend about respective axes A, C, B, D set horizontally, in use.

The roller 20 and the spindle 21 can be displaced between a closed configuration, in which they co-operate with the film 3b and determine winding thereof on the spindle 21, and an open configuration, in which they are at a distance from the film 3b and define a compartment traversed by the aforesaid film 3b.

Likewise, the roller 25 and the spindle 26 can be displaced between a closed configuration, in which they co-operate with the film 3b and determine winding thereof on the spindle 26, and an open configuration, in which they are at a distance from the film 3b and define a compartment traversed by the aforesaid film 3b.

In greater detail, the axes B, D of the spindles 21, 26 are set above the axes A, C of the rollers 20, 25.

The axes D, C are set closer to the fork 10 of the axes B, A, respectively.

The rollers 20, 25 are moreover driven in rotation about the corresponding axes A, C by respective motors 22 (just one of which is illustrated in Figure 17) , whilst the spindles 21, 26 are mounted idle about the corresponding axes B, D.

The forming unit 8 further comprises (Figures 2 to 10, 17 and 18) : - a machine bed 30;

- two pairs of guides 33, 34 carried by the machine bed 30 and extending in the direction T;

- a supporting body 31, which is able to slide on the guides 33, and which supports a lever 40, connected to the roller 20 in such a way that it can turn about an axis E eccentric with respect to the axis A, and supports a lever 41, connected to the spindle 21 in such a way that it can turn about an axis F eccentric with respect to the axis B;

- a supporting body 32, which is able to slide on the guides 34, and which supports a lever 42, connected to the roller 25 in such a way that it can turn about an axis G eccentric with respect to the axis C, and supports a lever 43, connected to the spindle 26 in such a way that it can turn about an axis H eccentric with respect to the axis D; - a pair of actuator assemblies 35, 37, carried by the supporting body 31 and designed, respectively, to bring about rotation of the lever 40 about the axis E and of the lever 41 about the axis F; and

- a pair of actuator assemblies 36, 38, carried by the supporting body 32 and designed, respectively, to bring about rotation of the lever 42 about the axis G and the lever 43 about the axis H.

In particular, the axes E, F, G, H are parallel to the axes A, B, C, D. The supporting body 32 is set laterally with respect to the supporting body 31 in a direction orthogonal to the direction T and set horizontally, in use.

The supporting bodies 31, 32 are identical to one another and, consequently, just one (i.e., the supporting body 31) is described in what follows; parts of the supporting bodies 31, 32 that are the same as one another or correspond to one another are designated in the attached figures by the same reference numbers.

The supporting body 31 basically comprises (Figures 2 and 17) a horizontal table 28, which is able to slide on the guides 33, a pair of orthogonal plates 29, carried fixedly by the table 28 itself, and an arm 27, fixed to the plate 29 and extending on the opposite side of the plate 29 with respect to the table 28.

Translation of the supporting bodies 31, 32 on the respective guides 33, 34 is determined by a pair of variable-length actuators 39, each having a liner, fixed to the machine bed 30, and a piston, which is able to slide with respect to the liner parallel to the direction T and is fixed to the table 28 of the corresponding supporting body 31, 32.

The levers 40, 42 comprise first ends hinged to the plates 29 of the respective supporting bodies 31, 32 about respective axes E, G and second ends, opposite to the first ends, fixed to the axes A, C of respective rollers 20, 25.

Likewise, the levers 41, 43 comprise first ends, hinged to the arms 27 of respective supporting bodies 31, 32 about the respective axes F, H, and second ends, opposite to the first ends, fixed to the axes B, D of respective spindles 21, 26.

Each of the actuator assemblies 35, 36 basically comprises ( Figure 2 ) :

- a liner 51, fixed to a plate 54 of the corresponding supporting body 31, 32;

- a piston 52, which is able to slide with respect to the liner 51 and has a first axial end housed within the liner 51; and

- a lever 53, which can turn about the corresponding axis E, G fixedly with respect to the corresponding lever 40, 42 and is fixed to a second axial end, opposite to the first axial end, of the piston 52.

Each of the actuator assemblies 37, 38 basically comprises:

- a liner 55, fixed to the table 28 of the corresponding supporting body 31, 32; - a piston 56, which is able to slide with respect to the liner 55 and comprises a first axial end housed within the liner 55; and

- a lever 57, which can turn about the corresponding axis F, H fixedly with respect to the corresponding lever 41, 43 and is fixed at a second axial end, opposite to the first end, to the piston 56.

In particular, exit of the pistons 52 from the respective liners 51 determines clockwise rotation of the levers 53 and 40, 42 about the respective axes E, G and hence clockwise rotation of the axes A, C of the rollers 20, 25 about the respective axes E, G.

Exit of the pistons 56 from the respective liners 55 determines counterclockwise rotation of the levers 57 and 41, 43 about the respective axes F, H and hence counterclockwise rotation of the axes B, D of the spindles 21, 26 about the respective axes F, H.

In particular, the plates 54 of the supporting bodies 31, 32 face one another and are set between the plates 29 in a direction orthogonal to the direction P.

The machine 1 further comprises a plurality of nozzles 58 (visible in Figure 2) , designed to blow air between the spindle 21, 26 and the film 3b being wound on the spindle 21, 26 itself so as to guarantee an adequate recovery of the film 3b, i.e., a controlled contraction of the film 3b itself.

The air blown by the nozzles 58 moreover assists winding of the film 3b on the spindle 21, 26.

The cutting unit 9 basically comprises (Figures 2, 11 and 12) :

- an L-shaped lever 65, comprising, in turn, an arm 66 hinged to the machine bed 30 about an axis L parallel to the axes A, B, C, D, E, F, G, H, and an arm 67 orthogonal to the arm 66;

- an L-shaped lever 70, comprising, in turn, an arm 71 hinged, about an axis M parallel to the axis L, to the arm 67, and an arm 72 having a free end 73 shaped like a roller with its axis parallel to the axes L, M; - an actuator 75, which is designed to bring about rotation of the lever 65 about the axis L and comprises a liner 76, fixed to the bed 30 of the machine 1, and a piston 77, which is able to slide with respect to the liner 76 and has an axial end opposite to the liner 76 fixed to a lever 78 that is able to turn about the axis L fixedly with respect to the lever 65; and

- an actuator 80, which is designed to bring about rotation of the lever 70 about the axis M and comprises a liner 81, fixed to the arm 67 of the lever 65, and a piston 82, which is able to slide with respect to the liner 81 and has an axial end fixed to a plate 83 projecting in cantilever fashion from the arm 71 of the blade 70.

In greater detail, when the piston 77 is retracted inside the liner 76, the lever 65 rotates about the axis L in a counterclockwise direction through ninety degrees, moving from a first configuration illustrated in Figures 2, 7, 10 and 11 to a second configuration illustrated in Figures 8, 9, 10 and 12.

As may be seen in Figure 11, when the lever 65 is in the first configuration, the arm 67 is horizontal and is set on the opposite side of the axis L with respect to the axes A, B of the roller 20 and of the spindle 21 set in the position R, and the lever 70 does not interfere with the film 3.

As may be seen in Figure 12, when the lever 65 is in the second configuration, the arm 67 is vertical and extends from the arm 66 towards the film 3b, and the end 73 of the lever 70 interferes with the film 3b in a position set between the spindle 26 (or 21) and the spindle 21 (or 26) . There is thus defined a third portion P3 of the film 3b, which is set between the portions P^, P2 and defines the section S. In particular, the portion P3 extends between the spindle 21 (or 26) and the end 73.

Exit of the piston 82 from the liner 81 determines rotation of the lever 70 in a counterclockwise direction about the axis M.

When the lever 65 is in the second configuration, the extension of the piston 82 brings the lever 70 from a first configuration (illustrated in Figure 12) to a second configuration (Figures 13 and 14) .

When the lever 65 is in the second configuration and the lever 70 is in the first configuration (Figure 12) , the arm 71 extends on the opposite side of the arm 67 with respect to the axis M, and the axis of the roller defining the end 73 and the axis D (or B) of the spindle 26 (or 21) set in the position R are at a first distance. When both of the levers 65, 70 are in the respective second configurations (Figures 13 and 14) , the arm 71 is set on top of the spindle 26 (or 21) , and the axis of the roller defining the end 73 is at a second distance, smaller than the first distance, from the axis D (or B) of the spindle 26 (or 21) , set in the position R. Consequently, in the respective second configuration, the lever 70 exerts a tensile stress on the portion P3 of the film 3b comprised between the spindle 21 and the end 73. More precisely, the portion P3 bends back on the part of the film 3b wound on the roller 25 (or 20) , whilst the portion of the film 3b extending between the end 73 and the reel 2 is bent back, in turn, on the portion P3 itself.

The lever 70 further comprises:

- the cutting element 90 (Figures 13, 14 and 15), which is hinged to the arm 72 of the lever 70 about an axis N parallel to the axes L, M and carries in cantilever fashion a plurality of teeth 91 designed to cut the section S of the film 3b set between the spindle 21, located in the first position, and the end 73; and

- an actuator 85, which is designed to bring about rotation of the cutting element 90 about the axis L.

More precisely, the actuator 85 comprises a liner 86 having a first end fixed to the plate 83, and a piston 87, which is able to slide with respect to the liner 86 and has an end, opposite to the second end of the liner 86, fixed to a lever 88, angularly fixed to the cutting element 90 about the axis N.

When the piston 87 is retracted within the liner 86, i.e., displaced to the right as viewed in Figures 13 and 14 , the cutting element 90 rotates in the counterclockwise direction about the axis N so as to extract the teeth 91 from the arm 72

(Figure 14) . Instead, when the piston 87 extends from the liner 86, i.e., when it is displaced to the left as viewed in Figures 13 and 14, the cutting element 90 rotates in a clockwise direction about the axis N so as to bring the teeth 91 back within the arm 72.

The fork 10 is mobile in a direction parallel to the axes A, B, C, D so as to cause recession of the reel 2 formed by the spindle 21, 26 set in the first position.

In use, the film 3a having the second thickness is wound off the reel 5 and is guided by first rollers 6 up to the station 7.

Inside the station 7, the film 3a traverses the compartment defined by the rollers 11, 12, which can turn about respective axes at different velocities.

The action of the rollers 11, 12 stretches the film 3a, giving rise to a film 3b having the second thickness smaller than the first thickness.

The second rollers 6 guide the film 3b up to the forming unit 8. Said second rollers 6 also have the purpose of stabilizing the material after the stretching step, i.e., of enabling the material of the film 3b to "shrink" , thus releasing as far as possible the elastic tensile stress present in the material of the film 3b itself after the stretching step.

The operation of the forming unit 8 is described starting from an initial condition, schematically illustrated in Figure 3.

In said initial condition, the roller 20 and the spindle 21 are set in the corresponding closed configuration, whilst the roller 25 and the spindle 26 are set in the corresponding open configuration. In said initial condition, moreover, the roller 20 is driven in rotation by the motor 22 about the axis A, and the spindle 21 occupies the position R.

Finally, in said initial condition, the levers 65 and 70 are in the respective first configurations, the teeth 91 of the cutting element 90 are housed . within the arm 72 of the lever 70, and the roller 25 is stationary.

The film 3b is supplied by the second rollers 6 parallel to the direction T and gains access to the unit 8.

The portion P^ of the film 3b co-operates with the roller 20 rotating about the axis A and is wound in a counterclockwise direction on the spindle 21, thus starting formation of the reel 2.

In order to favour proper positioning of the film 3b on the spindle 21, the film 3b can be manually curved and folded back on the spindle 21 itself.

This operation is to be carried out only the first time that a reel 5 of material is mounted.

In addition, the nozzles 58 blow air between the film 3b and the spindle 21 so as to guarantee proper winding of the film 3b on the spindle 21.

More precisely, the jet of air generated by the nozzles 58 assists movement of the film 3b, seeking to limit as much as possible the residual elastic components present after the stretching step.

The actuator assembly 36 adjusts the gripping force of the spindle 21 on the roller 20 so as to guarantee proper winding of the film 3b on the spindle 21.

Next, the actuators 39 are actuated so as to displace the supporting bodies 31, 32 on the respective guides 33, 34 in opposite directions along T (Figures 4 and 5) . More precisely, the roller 20 and the spindle 21 advance fixedly with respect to one another from the position R towards the position Q along T in the closed configuration, whilst the roller 25 and the spindle 26 are displaced towards the position R fixedly with respect to one another in the open configuration so as not to interfere with the roller 20 and the spindle 21.

During the travel of displacement of the roller 20 and of the spindle 21 towards the position Q, the film 3b continues to be wound on the spindle 21, thus increasing the diameter of the reel 2.

During the travel of displacement towards the position R, the roller 25 starts to be driven in rotation about the axis C by the corresponding motor 22.

Furthermore, at the end of said path of displacement (Figure 6) the roller 25 and the spindle 26 are in the open configuration, whereas the roller 20 and the spindle 21 are in the closed configuration.

At this point, the operation of cutting of the film 3b starts with consequent separation of the reel 2 from the remaining part of the film 3b.

In greater detail, the actuator assemblies 36, 38 turn the roller 25 and the spindle 26 with respect to the axes G, H in a clockwise direction and a counterclockwise direction, respectively, until the roller 25 and the spindle 26 are brought into the closed configuration (Figure 7) . Once set in the closed configuration, the spindle 26 is in the position R, and the roller 25 and the spindle 26 support the portion P2 of the film 3b. Rotation of the roller 25 forces the portion P2 of the film 3b to follow, at least in part, the profile of the spindle 26. At this point, first the actuator 75 displaces the lever 65 from the respective first configuration (Figure 7) to the respective second configuration (Figure 8) , and then the actuator 80 displaces the lever 70 from the respective first configuration to the respective second configuration.

During travel of the lever 70 from the first configuration to the second configuration, the end 73 bends the portion P3 of the film 3b, which extends from the spindle 26 on the opposite side of the spindle 21.

At this point, the piston 87 of the actuator 85 is retracted so as to bring about counterclockwise rotation of the cutting element 90 about the axis N and consequent exit of the teeth 91 from the arm 72.

The teeth 91 cut the section S of the portion P3 of the film 3b and separate the reel 2 from the remaining part of the film 3.

Next, as indicated in Figure 10, the actuator 85 brings the teeth 91 of the cutting element 90 back into the arm 72, the actuator 80 brings the lever 70 back into the first configuration, and the actuator 75 brings the lever back 65 into the first configuration.

Rotation of the roller 20 completes formation of the reel 2, whilst rotation of the roller 25 determines winding of a new reel 2' about the spindle 26.

At this point, the roller 20 is arrested and the actuator assemblies 35, 37 bring about rotation of the roller 20 and of the spindle 21, respectively, about the axes E, F until the corresponding open configuration is reached. When the roller 20 and the spindle 21 are in the open configuration, the reel 2 formed engages a circular seat of the fork 10. The next displacement of the fork in a direction parallel to the axis A determines unloading of the reel 2 from the machine 1.

Next, the reel 2' is formed in a way similar to what is described with reference to the reel 2.

In extreme synthesis, the roller 20 and the spindle 21 move towards the position R on the opposite side of the fork 10 in the open configuration, whereas the roller 25 and the spindle 26 move towards the position Q in the closed configuration, and the reel 2' is wound on the spindle 26.

Next, the roller 20 and the spindle 21 reach the closed configuration and support the portion Ε>2 of the remaining part of the film 3b, the cutting element 90 separates the reel 2', and finally the roller 25 and the spindle 26 reach the open configuration.

From an examination of the characteristics of the machine 1 according to the present invention, the advantages that it affords are evident.

In particular, cutting of the section S of the film 3b occurs whilst the roller 20 and the spindle 21, as well as the roller 25 and the spindle 26, are in the respective closed configurations .

Consequently, the reel 2 is separated from the film 3b when it is completing its own winding on the spindle 21 and when a new reel 2' is being wound on the spindle 26.

It follows that the machine 1 enables separation of the reel 2 formed by the film 3b, without stopping or slowing down advance of the film 3b itself.

Consequently, the machine 1 produces the reels 2 at a rate higher than traditional reeling machines, which require at least slowing-down of the film 3b during the step of separation from the reel 2.

Finally, it is clear that modifications and variations may be made to the machine 1 and to the method described and illustrated herein, without this implying any departure from the sphere of protection defined by the claims.

Claims

1.- A method for the production of reels (2) of film material having a first thickness (3b) starting from a film material having a second thickness (3a) greater than said first thickness, comprising the steps of:

- stretching the film material having said second thickness (3a) so as to obtain the film material having said first thickness (3b) ; - forming a reel (2) of material having the first thickness (3b) ; and

- executing an operation of cutting on said film material having said first thickness (3b) so as to separate said reel

(2) from the remaining part of said film material having the first thickness (3b) ; said method being characterized in that said step of forming said reel (2) comprises the steps of:

- winding a first end portion (Pl) of said film material having said first thickness (3b) on a first spindle (21; 26); and

- displacing, during said winding step, said first spindle (21; 26) into a first position (Q) ; said method being moreover characterized in that said step of executing said cutting operation comprises the steps of:

- supporting a second portion (P2) of said film material having said first thickness (3b) on a. second spindle (26; 21) set in a second position (R) , distinct from said first position (Q) ; and - cutting a section (S) of said film material having said first thickness (3b) ; said section (S) being set between said first and second portions (Pi, P2) •

2.- The method according to Claim 1, characterized in that said step of winding said material having said first thickness (3b) on said first spindle (21; 26) comprises the steps of: - setting said first spindle (21; 26) and a first roller (20; 25) in a closed configuration, in which they co-operate with said material having said first thickness (3b) ; and

- turning said first roller (20; 25) about a corresponding first axis (A; C) to wind said material having said first thickness (3b) on said first spindle (21; 26) ; said method being moreover characterized in that said step of displacing said first spindle (21; 26) comprises the step of displacing said first roller and said first spindle (20, 21; 25, 26) set in the closed configuration fixedly with respect to one another in a first direction (T) until said first spindle (21; 26) reaches said first position (Q) and with a sense oriented from said second position (R) to said first position (Q) .

3.- The method according to Claim 1 or Claim 2, characterized in that said step of supporting a second portion (P2) of said film material having said first thickness (3b) on a second spindle (26; 21) comprises the steps of: - setting said second spindle (26; 21) and a second roller (25; 20) in a closed configuration, in which they co-operate with said film material having the first thickness and wind it on said second spindle (26, 21); and

- turning said second roller (25; 20) about a corresponding second axis (C; A) for winding, at least in part, said film material having said first thickness (3b) on said second spindle (26; 21) .

4. - The method according to Claim 2 or Claim 3 , characterized in that it comprises the step of displacing said second spindle (26; 21) and said second roller (25; 20) , in an open configuration in which they are at a distance from said film material having said first thickness (3b) and fixedly with respect to one another, in said first direction (T) with a sense oriented from said first position (Q) to said second position (R) .

5.- The method according to Claim 4, characterized in that said step of displacing said second spindle (26; 21) and said second roller (25; 20) in an open configuration occurs simultaneously to said step of displacing said first roller and said ^' first spindle (20, 21; 25, 26) set in the closed configuration .

6.- The method according to any one of the preceding claims, characterized in that it comprises the step of blowing a current of air between said first spindle (25; 26) and said first roller (20, 21) during said winding step.

7. - The method according to any one of Claims 3 to 6 , characterized in that said step of cutting said section occurs when said first roller and said first spindle (20, 21; 25, 26) are in the respective closed configuration and said first spindle (20; 25) is in said first position (Q) , and when said second roller and said second spindle (25, 26; 20, 21) are in the respective closed configuration and said second spindle (21; 26) is in said second position.

8.- The method according to Claim 7, characterized in that said step of cutting said section (S) comprises the steps of: - bending a third portion (P3) of said film material having said first thickness (3b) via a roller (73) carried by a lever (70) ; said third portion (P3) being set between said first and second portions (Pi, P2) and defining said section (S) ; and

- extracting a cutting element (91) from said lever (70) for cutting said section (S) .

9.- A machine (1) for the production of reels (2) of film material having a first thickness (3b) starting from film material having a second thickness (3a) greater than said first thickness, comprising:

- a stretching station (7) supplied, in use, with said film material having the second thickness (3a) and supplying, in use, at output said film material having the first thickness (3b) ;

- means (8) for forming a reel (2) of material having said first thickness (3b) ; and

- cutting means (9) , designed to cut said film material having said first thickness (3b) and to separate said reel (2) from the remaining part of said film material having said first thickness (3b) ; said machine being characterized in that said forming means (8) comprise:

- a first spindle (21; 26) that can be displaced into a first position (Q) ;

- winding means (20; 25) , designed to wind a first end portion (Pl) of said film material having said first thickness (3b) on said first spindle (21; 26) and displaceable in said first position (Q) fixedly with said first spindle (21; 26) ;

- a second spindle (26; 21) that can be displaced into a second position (R) , distinct from said first position (Q) , at least when said first spindle (21; 26) is in said first position (Q) ; and

- supporting means (25; 20) interacting, in use, with said second spindle (26, 21) set in said second position (R) for supporting a second portion (P2) distinct from said first portion (P_]_) of said film of material having said first thickness (3b) ; said machine (1) being characterized in that said cutting means (9) comprise a cutting element (91) that can be displaced into a cutting position in which it cuts a section (S) set between said first and second portions (P^, P2) of said film material having said first thickness (3b) , when said first and second spindles (21, 26) are in said first and second positions (Q, R) , respectively.

10.- The machine according to Claim 9, characterized in that said winding means (20; 25) comprise a first roller (20; 25), which can be drawn in rotation about a first axis (A; C) ; said first roller and said first spindle (20, 21; 25; 26) being displaceable with respect to one another between a closed configuration, in which they co-operate with said film material having said first thickness (3b) and determine winding thereof on said first spindle (21; 26) , and an open configuration, in which they are at a distance from said film material having said first thickness (3b) ; said first roller and said first spindle (20, 21; 25, 26) being displaceable fixedly with respect to one another in the closed configuration in a first direction (T) with a first sense oriented from said second position to the first position (R, Q) to bring said first spindle (21, 26) into said first position.

11.- The machine according to Claim 9 or Claim 10, characterized in that said supporting means (25; 20) comprise a second roller (25, 20), which can be drawn in rotation about a second axis (C, A) ; said second roller and said second spindle (25, 26; 20, 21) being displaceable with respect to one another between a closed configuration, in which they cooperate with said film material having the first thickness (3b) , and an open configuration, in which they are at a distance from said film material having said first thickness (3b); said second roller and said second spindle (25, 26; 20, 21) being displaceable fixedly with respect to one another in said first direction (T) in the open configuration with a second sense oriented opposite to said first sense.

12.- The machine according to any one of Claims 9 to 11, characterized in that it comprises blower means (58) , designed to blow a current of air between said first spindle (21; 26) and said first roller (20, 25) to facilitate winding of said first portion (P^) on said first spindle (21; 26)

13.- The machine according to any one of Claims 10 to 12, characterized in that said cutting means (9) comprise:

- a first lever (65) , hinged to a fixed structure (30) of said machine (1) about a third axis (L) ;

- a second lever (70) , hinged to said first lever (65) about a fourth axis (M), comprising an end (73) shaped like a roller set on the opposite side of said fourth axis (M) and supporting said cutting element (91) ;

- first actuator means (75) for turning said first lever (65) about said third axis (L) between a first position of rest, in which said fourth axis (M) is set on the opposite side of said third axis (L) with respect to said second axis (C; A) of said second roller (25; 20) set in the second position (R) , and a first operative position, in which said fourth axis (M) is set in said first direction (T) between said second axis (C, A) of said second roller (25; 20) set in said second position (R) and said first axis (A; C) of said first roller (20; 25) set in said first position (Q) ; and

- second actuator means (80) , designed to displace said second lever (70) about said fourth axis (M) between a first position of rest and a second operative position in which said end (73) bends a third portion (P3) of said film material having said second thickness (3b); said third portion (P3) being set between said first and second portions (Pi, P2) ^and defining said section (S) .

14. - The machine according to Claim 13 , characterized in that said cutting element (91) is hinged about a fifth axis (N) to said second lever (70) and in that it comprises third actuator means (85) , designed to displace, when said first and second levers (65, 70) are in the respective second operative positions and said second spindle (21, 26) is in said second position (R) , said cutting element (91) between a third position of rest, in which said cutting element (91) is at a distance from said film material having said second thickness (3b) , and said cutting position.