Holding and supporting group of a winding spindle in a plastic film winding machine

A holding and supporting group of a winding spindle in a machine for winding plastic film onto spools includes a winding reel positioned between two uprights, wherein a first upright carries a rotating plate which cantilever-supports three spindles and a central shaft, wherein the central shaft is supported at the other end by the second upright, wherein, in correspondence with a free end of the central shaft, there is a star-shaped plate with three supporting arms for each free end of the three spindles through a respective toggle lever mechanism driven by an actuator carried on a lever articulated with respect to the star-shaped plate, and in turn caused to oscillate between an operative blocking position of the respective spindle and a rest position for releasing the respective spindle by an additional actuator.

The present invention relates to a holding and supporting group of a winding spindle in a machine for winding plastic film onto spools.

Various supporting systems of the spindle present in each winding reel are currently used in the field of machines for winding plastic film onto spools.

This support is generally effected between a tip and tailstock which are axially moved towards or away from each other in order to axially block or release the spindle for removing the spool(s).

This technology currently used creates a first problem of time loss for moving the tip and tailstock towards and away from each other for loading the cores and removing the wound spools.

A second problem relates to the vibrations created due to the end supporting system between the tip and tailstock that does not perfectly clasp the spindle and does not guarantee a stabile axial blockage.

Another particular problem relates to the possible flexions that arise in an arrangement of the spindle between facing front end supports.

Furthermore, in certain types of these winding machines, spools can be wound onto cores having a diameter of 2 or 3 inches defined with respect to common use as “manual” and “automatic”.

Spools for “manual” use must be produced with a relatively short length of wound material and consequently in order to reach high production rates, a spool-change cycle must be effected in short times. To produce 150 ml spools at 600 m/min, for example, 4 changes per minute are required, and therefore a change every 15 seconds.

This does not allow an online production of spools having an extremely reduced diameter and weight at high rates, as desired.

Furthermore, the necessity of producing very thin films (from 6 μm to 12 μm indicatively) has led to the study and creation of various expedients suitable for eliminating the basic problems that arise during the winding of such thin films.

The necessity of effecting extremely rapid change cycles makes it necessary, for example, to extract the spools produced from the reel without moving the same. This operation can evidently only be effected by freeing an end of the reel itself in order to extract the spools produced, and also insert new cardboard cores.

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

A further objective of the present invention is to provide a holding and supporting group of a winding spindle in a machine for winding plastic film onto spools, which reduces the core-substitution and spool-extraction times.

Another objective of the present invention is to provide a holding and supporting group of a winding spindle in a machine for winding plastic film onto spools, which eliminates the vibrations of tip-tailstock end supporting groups.

Yet another objective of the present invention is to provide a holding and supporting group of a winding spindle in a machine for winding plastic film onto spools, which ensures a secure support and blockage in the spindle, even with the possibility of its rapid removal.

A further objective of the present invention is to provide a holding and supporting group of a winding spindle in a machine for winding plastic film onto spools, which eliminates possible flexions of the spindle positioned between its supports.

In view of the above objectives, according to the present invention, a holding and supporting group of a winding spindle in a machine for winding plastic film onto spools has been conceived, having the characteristics specified in the enclosed claims.

The structural and functional characteristics of the present invention and its advantages with respect to the known art will appear even more evident from the following description, referring to the enclosed drawings, which show an embodiment of a holding and supporting group of a winding spindle produced according to the present invention.

With reference first of all toFIG. 1, this illustrates a raised schematic side view showing part of a winding machine in the area which comprises a holding and supporting group of a winding spindle11produced according to the invention.

The holding and supporting group11is positioned inside two vertical uprights12,13which form the shoulders of the winding machine. A first upright12cantilever carries, on a rotating supporting plate14, a central shaft15, supported at the other end in correspondence with the second upright13.

The plate14, rotating around the central shaft15, also carries three spindles,16,17and18, arranged at 120° with respect to each other, which complete the winding reel.

According to the invention, the holding and supporting group of a winding spindle11produced according to the invention, is associated with the reel.

The group11comprises a star19or shaped plate with three selective supporting arms of the free end of the three spindles16,17and18. More specifically, the grip of the single spindle in correspondence with each end of the three spindles16,17or18is effected by a respective toggle lever mechanism.

Said toggle lever mechanism is driven by an actuator30and is carried on a lever20in turn caused to oscillate between an operative position and a rest position. The lever20can in fact be moved between an operative blocking position of the respective spindle16,17or18and a rest position for releasing the respective spindle16,17or18by means of a further actuator32.

The toggle lever mechanism comprises a jaw21consisting of a bellcrank or toggle lever22hinged by means of a pin23to an upper end of the lever20. The lever20also comprises, close to said pin23, a housing24having a complementary form with respect to the jaw21creating a seat for the end of the single spindle16,17or18.

A biscuit25is connected at a first end by means of a pin26to an intermediate portion of the bellcrank22and at a second end by means of a pin27to a loop28integral with a stem29of the actuator30, consisting of a pneumatic cylinder, arranged integrally with the lever20.

The lever20is, in turn, hinged, by means of a pin31, at an opposite end to that carrying the jaw21, to the star-shaped plate19. The lever20is caused to oscillate around said pin31by means of the further actuator32, such as a pneumatic cylinder. The actuator32is hinged at a first end, by means of a pin37, on an arm of the star-shaped plate19, and one of its stems33, at a free end, is connected through a pin34to the lever20.

In particular,FIGS. 3a, 3band 3care schematic views of the functioning of the group of the invention in different consecutive operative phases.

An extremely secure and reliable holding “system” of the single spindle16,17or18is therefore produced, which also minimizes the stoppage times.

The necessity of effecting very rapid change cycles with the group of the invention, in fact, allows spools35(of which three are shown inFIG. 1) produced by the reel, to be extracted without moving the same. According to the invention, in fact, this operation can only be effected by freeing an end of the spindle of the reel in question, to allow the spools35produced to be extracted.

The movable gripping “system” of an end of the spindle16,17or18of the reel allows this operation to be effected and at the same time ensures a firm hold (wedge-insertion) during the winding phase. All the vibrational phenomena typical of the unstable or resting systems so far adopted are therefore eliminated.

FIGS. 3a-3cand 4a-4bshow the functioning of a group according to the invention, which can be summarized as follows.

FIGS. 3aand 4ashow how, under a normal winding condition of the spools35, the pneumatic cylinder30drives the lever22with the relative jaw21of the toggle lever mechanism to be re-closed on the free end of the spindle16, as for all the other spindles17and18. For the sake of simplicity, mention will now be made of the spindle16alone. Said end of the spindle16, moreover, is housed in the seat24of the lever20. This guarantees the stable tightening of the spindle16. In a preferred embodiment, in order to completely eliminate the risk of disengagement, an irreversibility of the toggle lever mechanism is envisaged. It should in fact be noted that, in a blocking position of the toggle lever mechanism, the pins26,27of the biscuit25are aligned so as to be, on the one hand, in an aligned position with the jaw21and, on the other hand, perpendicular to the stem29of the actuator30. The stable tightening of the spindle16,17and18of interest is thus created and the risk of disengagement is completely eliminated thanks to the irreversibility of this position. It is in fact impossible for the elements collaborating with each other, the bellcrank22and lever20, to move with respect to each other, even accidentally, as also the respective jaw21and housing24.

It should also be pointed out that the lever20is angularly arranged so as to be close to the positioning axis of the spindle16or other spindle of interest. For this purpose, the angular position of the lever20is guaranteed by the extension of the stem33of the pneumatic cylinder32, and its blockage is effected by means of a specific hydraulic brake36, which exploits the incompressibility of the oil contained therein to guarantee its absolute immobility and stability of position.

FIG. 3bshows a preliminary position to the extraction phase of the spools35, in which the pneumatic cylinder30effects the opening of the bellcrank or toggle lever mechanism22.

The pneumatic cylinder32withdraws its stem33and exerts a return movement on the lever20in an anticlockwise direction so as to create space for the passage of the spools produced35which can be discharged.

Once empty cores43have been charged onto the spindle of interest, the closing procedure is obviously the exact contrary.

A group according to the present invention defines a situation of double wedge-insertion for the spindles of the winding reels, equalizing any possible flexions created by the force of possible contact rolls (not shown) and consequently balancing the peripheral velocities of the two ends of the same spindle.

FIG. 2clearly shows the wedge-insertion condition guaranteed by the toggle lever mechanism22on the end of the spindle16of the reel that must be freed when the spools35are discharged. The extreme proximity of the jawed seat21of the toggle lever mechanism22with respect to the winding area of the film, ensures a significant wedge-insertion effect. The free inflection length is reduced and above all, the symmetry of the behaviour of the spindle of the reel along the whole length is guaranteed.

For a better understanding,FIGS. 4aand 4billustrate the main functioning phases of the toggle lever mechanism22. When the stem29of the pneumatic cylinder30is in an extracted position, the opening torque C of the jaw21is theoretically infinite, as it has to overcome a force F which is expressed along its own rotation axis.

Only the re-entry movement of the stem29of the pneumatic cylinder32(FIG. 4b) can “free” said jaw21, allowing its rotation around its fulcrum or pin23.

With the present invention, a movable tightening “system” of an end of the spindle16,17or18of the reel is created, which allows a rapid and stable operating position and an equally rapid removal of the spools. At the same time, a firm hold (wedge-insertion) is guaranteed during the winding phase, thus eliminating vibrational phenomena typical of the known unstable or resting systems, such as for example tip-tailstock end supporting groups.

A holding and supporting group of a winding spindle in a machine for winding plastic film onto spools is also created according to the invention, which ensures a firm supporting and blockage in the spindle, together with its rapid possibility of removal.

The objective mentioned in the preamble of the description has therefore been achieved.

The forms of the structure for producing a group of the invention, as also the materials and assembly modes, can obviously differ from those shown for purely illustrative and non-limiting purposes in the drawings.

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