WO2013156123A1

WO2013156123A1 - Constant pull-winding unit for use in production lines of plastic films

Info

Publication number: WO2013156123A1
Application number: PCT/EP2013/001064
Authority: WO
Inventors: Eraldo Peccetti
Original assignee: Colines S.P.A.
Priority date: 2012-04-17
Filing date: 2013-04-10
Publication date: 2013-10-24
Also published as: ITMI20120623A1

Abstract

A constant pull-winding unit for use in production lines of plastic films comprises a plurality of reels (14-16) constrained to a reel-holder star (13) that rotates around its own axis (10), said reels (14-16) being positioned around said reel-holder star (13) so that at least a first reel (14) of said plurality of reels is in an operative winding position of a film (11) forming a bobbin (17), wherein said reels (14-16) are associated with movable contact means (28) between a first contact position with said bobbin (17) being wound onto said at least one reel (14-16) and a second distal position from said bobbin (17). According to the invention, said contact means consist of a motorized roll (28) positioned at the end of oscillating arms (25) and arranged on a supporting group (27) which can be rotated independently with respect to said axis (10) of said reel-holder star (13) in order to maintain a contact position of said motorized roll (28) with said bobbin (17) also during the rotation of said reel- holder star (13) during the reel change.

Description

CONSTANT PULL-WINDING UNIT FOR USE IN PRODUCTION LINES OF PLASTIC FILMS

The present invention relates to a constant pull- winding unit to be used in production lines of plastic films, in particular extendable plastic films.

In the packaging field, extendable plastic film, also called film stretch, is a product which is widely- used, mainly in Europe and in the United States.

This type of film has numerous uses and is suitable for covering most products of common use, both in the industrial field and household environments.

Once produced, this film is wound into bobbins, for example by means of a unit and method object of European patent EP 2 212 228 in the name of the same Applicant of the present patent application.

These techniques are excellent, but can cause "non- perfect" windings from an aesthetical point of view in the final winding coils, which however do not jeopardize the functionality of the film.

in the unit described in patent EP 2 212 228, for example, which should be considered as being incorporated herein for a more complete understanding of the invention, during the application of the film on the single reel, specific contact means 26-28 are envisaged. These contact means maintain a constant contact with the winding bobbin, in a position downstream of the feeding direction of the film, which is maintained constantly during the whole cycle.

As the contact means 26-28, for example having the form of cylinders, are fixed on the reel-holder star, they follow the rotation of the star, always remaining in the same position with respect to the single reel.

With this arrangement, they leave a wide tail of film which is not perfectly clamped and pressed, with a non-constant pull with respect to the film of the bobbin which is being completed. There is consequently the tendency of forming creases and above all, the film does not remain flat and stretched and does not constantly cover the entire transversal dimension of the bobbin .

This defect causes the formation of bobbins of film in which, in the last coils have the film that in transversal direction is not perfectly stretched, creating an unpleasant image for the user, even if, as mentioned, it maintains its functionality.

As a result, users do not like bobbins having creased coils at the end of the winding and a not completely flat arrangement of the film on the bobbin.

The resulting economical damage is considerable due to the quantities of film present on the end-bobbin which, however, has this anomaly only in the last few coils of the winding.

Furthermore, the manufacturing plants must in any case maintain productions at a high rate and always be able to effect changes at high velocities, without any slowdowns and stoppages for any reason.

A general objective of the present invention is to solve the above drawbacks of the known art in a simple, economical and particularly functional manner.

Another objective of the present invention is to provide a winding unit to be used in production lines of plastic films, capable of guaranteeing an optimum and constant winding pull from the first to the last meter of film, also operating at high production velocities .

In view of the above objectives, a constant pull- winding unit has been conceived, according to the present invention, for use in production lines of plastic films, having the characteristics described in the enclosed claims.

The structural and functional characteristics of the present invention and its advantages with respect to the known art will appear more evident from the following description referring to the enclosed drawings, which show a constant pull-winding unit to be used in production lines of plastic films, produced according the innovative principles of the invention itself .

In the drawings :

- figure 1 shows a raised schematic side and sectional view of a winder according to the present invention;

- figure 2 shows an enlarged schematic view of a section of the unit shown in figure 1;

- figures 3 to 8 show various subsequent phases of the winding cycle and changing of the bobbins of plastic films in a unit according to the present invention.

In particular, with reference to figure 1, this shows a winding unit according to the invention, in which the winding scheme can be seen of a plastic film 11 when inserted and going through the various sections forming the unit .

The constant pull-winding unit according to the invention comprises a supporting structure 12 equipped with a reel-holder star 13 rotating around an axis 10. The reel-holder star 13 carries a plurality of reels 14-16 positioned around the same, each equipped with a mandrel around which a bobbin 17 of plastic film 11 is wound. In the example, there are three reels 14-16 for contemporaneously effecting the winding operations of the bobbins, discharging the completed bobbins and loading the cores onto which a new bobbin is to be wound. The arrangement of the three reels 14-16 illustrated is, for example, interspaced by 120° from each other on the reel-holder star 13.

The reels 14-16 are driven in rotation by their own motor (not shown), controlled by an inverter.

The positioning of the mandrels and feeding of the cores are effected as described in patent EP 2 212 228 in the name of the same Applicant.

Figures 2 to 8 show in clearer and more specific detail what is envisaged for cooperating with the reel- holder star 13.

In particular, figure 2 shows how the plastic film 11 is fed towards a first reel 14, where there is a specific motorization suitable for piloting the winding of the film 11 at a certain winding rate around the reel 14 which is in said angular position.

In correspondence with the angular winding position, there is also a pulling and pressure device 18 suitable for regulating the tensioning of the film 11 during a part of the winding.

Said pulling and pressure device 18 comprises a roll 19 which, during the winding of the film 11 onto the single reel 14-16, is in contact with the corresponding reel 14-16, and a further roll 20 which forms a drawing calender. The roll 19 and the roll 20 are supported on a pair of oscillating levers 21 by- means of pneumatic cylinders 32 around a central axis 22.

During the winding and bobbin-change phases, the above device 18 has an oscillating movement around the axis 22 in order to maintain the same contact pressure on the bobbin being formed or already formed.

Furthermore, in correspondence with the winding position, a blade 23 is envisaged for cutting the film 11 following the end of the winding phase of a whole bobbin 17 of film.

The intervention of the transversal cutting blade 23, carried by arms 34, is controlled by an actuator, such as the cylinder 24 shown in figure 1.

In addition, according to the present invention, oscillating contact means are envisaged, which act on the bobbin at each moment of the winding phase and changing phase, and which can oscillate around the same axis 10 of the reel-holder star 13.

These contact means comprise a pair of arms 25, opposite to each other and oscillating, each constrained, by means of a pin 26 to a supporting group 27 that can rotate around the same axis 10 of the reel- holder star 13. The single arm 25 is equipped, on one of its free ends, with a terminal part of a motorized roll 28. At least one actuator is also envisaged, such a cylinder 29, hinged in 30 at one of its ends to the supporting group 27 and at the other end hinged in 31 to the single arm 25, which causes the oscillation of the arm and engagement or non-engagement of the motorized roll 28 on the bobbin 17 of a single reel 14- 16.

This specific expedient allows the drawbacks of the known art to be eliminated as the film 11 being wound onto the bobbin 17 is never abandoned, not even in the final part where there is a change from the reel 14 to the subsequent reel 15.

Furthermore, the motorized roll 28 rolls around the bobbin being formed and changed 17, always maintaining a perfect contact with the same, thus eliminating any possibility of forming creases or folds or also air bubbles .

Figures 2 to 8 very clearly illustrate the phases which create such a precise and correct functioning of the unit, as well as the continuous contact of the film with elements which ensure that it is kept in a flat position in its transversal dimension.

Figure 2, as mentioned, shows the initial phase, in which the bobbin 17 positioned on the reel 14 is being wound. The normal winding of the plastic film 11 takes place on the reel 14, arranged in winding position, i.e. with the pulling and pressure device 18 in contact with the film, or with the bobbin being formed.

In this phase, according to the invention, the motorized roll 28 is not in contact with the film 11, thus simplifying the functioning.

At the end of this first winding phase, i.e. when the bobbin 17 of film 11 has been completed (figure 3) , the so-called changing phase is initiated.

The motorized roll 28 is first of all brought into contact with the bobbin 17 thanks to the action of the cylinder 29, which withdraws its rod, causing a partial rotation of the arm 25 with respect to the support group 27.

Figure 4 shows how, immediately afterwards, the roll 19 of the pulling and pressure device 18 becomes detached from the bobbin 17 and starts the rotation of the reel-holder star 13, for example, by about 35°, with the advancing of the subsequent empty reel 15 towards the winding position. In this phase, the supporting group 27 carrying the arm 25 and the roll 28 does not rotate, even if the roll 28 is in contact with the bobbin 17, now almost completely formed. It should be noted that, according to the invention, the motorized roll 28 is gradually rotated around the bobbin 17 so that it is in contact with the same, always in correspondence with the tangency position of the film 11 with respect to the bobbin 17. This is achieved in the example thanks to the presence of the supporting group 27 rotatable around the axis 10 of the reel -holder star 13 regardless of the rotation of the reel-holder star 13.

Figure 5 shows how the subsequent further rotation of the reel-holder star 13 is effected, by a predetermined additional angular portion, for example for a total of 120° clockwise.

In this way, the second reel 15 is brought in correspondence with the winding position.

During this phase, the roll 19 of the pulling and pressure device 18 is brought into contact with one or more formation cores 33 of a new bobbin fed onto the respective mandrel.

Contemporaneously, the supporting group 27 which carries the arm 25 and roll 28, also rotates, for example by 85°, keeping the roll 28 in contact on the bobbin 17 almost completely formed, always in correspondence with the tangency point of the film 11 on the bobbin 17. The cutting of the plastic film 11 is effected in this position, as shown in the subsequent figure 6. The blade 23, in fact, descends, held by the arms 34, which are oscillated by the cylinders 24. The bobbin 17 is then stopped, whereas the roll 28 continues to rotate also completing the winding of the short tail of film 11.

Figure 7 shows how the cutting blade 23 is brought back to the raised rest position.

The roll 28 is stopped and its detachment from the bobbin 17 is determined by rotation of the arm 25 around the pin 26.

Finally, figure 8 shows how the supporting group 27 is brought to effect a rotation opposite to that effected (about -85°) bringing the roll 28 positioned on the arm 25 back above the second reel 15 in the winding position, where the above loading of the cores 33 is effected.

These rotating contact means that act on the bobbin in both its winding phase and in the changing phase and that rotate around the same axis 10 of the reel-holder star 13, ensure a uniform and constant winding for the whole transversal width of the bobbin also for the last coils of the same, eliminating the problems of the known art. This is because the contact between the roll 28 and the bobbin 17 is always in correspondence with the inlet and tangency point of the film with respect to the bobbin.

The "clamping" is therefore always tangent with the film 11, preventing narrowing of the width of the film and the formation of air bubbles between the coils of the bobbin.

Furthermore, also in this case the "pressing" of air between the coils is guaranteed, avoiding any kind of defect.

In this way, a guide is also created for the last metres of film, which, during the final part of the changing phase, would otherwise have no contact, and cause the formation of transversal creases and the encapsulation of air.

From what is described above with reference to the figures, it is evident how a constant pull-winding unit for use in production lines of plastic films according to what is specified, is particularly useful and advantageous .

With the winding unit described, bobbins of high- quality plastic film can therefore be produced.

The protection scope of the invention is therefore delimited by the enclosed claims.

Claims

1) A constant pull-winding unit for use in production lines of plastic films comprising a plurality of reels (14-16) constrained to a reel-holder star (13) that ro- tates around its own axis (10), said reels (14-16) being positioned around said reel-holder star (13) so that at least a first reel (14) of said plurality of reels is in an operative winding position of a film (11) forming a bobbin (17), wherein said reels (14-16) are associated with movable contact means (28) between a first contact position with said bobbin (17) being wound onto said at least one reel (14-16) and a second distal position from said bobbin (17) , characterized in that said contact means consist of a motorized roll (28) positioned at the end of oscillating arms (25) and arranged on a supporting group (27) which can be rotated independently with respect to said axis (10) of said reel-holder star (13) in order to maintain a contact position of said motorized roll (28) with said bobbin (17) also during the rotation of said reel -holder star (13) during the reel change.

2) A pull -winding unit according to claim 1, characterized in that said motorized roll (28) , when in contact with said bobbin, is always arranged in correspondence with the tangency position of the film (11) with respect to said bobbin (17) . 3) A pull-winding unit according to claim 1 or 2 , characterized in that said oscillating arms (25) are carried by pins (26) with respect to said supporting group (27) and support ends of said motorized roll (28) , driving ac- tuators (29) being envisaged, of the rotation of said arms with respect to said second supporting group (27) .

4) A pull -winding unit according to any of the previous claims, characterized in that a pulling and pressure device (18) is envisaged in correspondence with said opera- tive winding position, suitable for regulating the tensioning of the film (11) during winding.

5) A method for the winding of bobbins of plastic film onto a single reel (14-16) of a reel-holder (13) comprising the phases consisting in:

- bringing a first reel (14) loaded with a first core (33) into a winding position and initiating the winding of a film (11) around said core (33) at a winding rate, forming a bobbin (17) , a pulling and pressure device (18) being envisaged in contact with the bobbin in formation; - bringing a motorized roll (28) rotatable around an axis (10) of said reel-holder (13) into contact with said bobbin (17) when the bobbin has been completed;

- rotating said reel-holder (13) to bring said first reel (14) carrying the completed bobbin to a distal position from said winding position, said motorized roll (28) be- ing kept in contact with said bobbin (17) in correspondence with the tangency position of the film (11) with respect to said bobbin (17) ;

- effecting the cutting of said film (11) ;

- stopping said bobbin (17) and detaching said motorized roll (28) from said bobbin (17) ;

- bringing said motorized roll (28) back into correspondence with a second reel (15) detached from cores of a bobbin to be formed.

6) The winding method according to claim 5, also comprising the phase consisting in:

- bringing a second reel (15) into a winding position.