Patent Description:
In further detail, the invention concerns a packaging machine for film-wrapping a roll of web material, of the type comprising a cylindrical body and two flat sides, in particular, but not exclusively, paper.

It is clear that the same packaging machine according to the invention can be used also for film-packaging goods that have at least one flat surface on which the film can be terminated, once the wrapping has been completed.

In the paper roll sector, one of the packaging techniques used is axial wrapping of the roll with film, where the film is wound in the longitudinal direction of the roll and always terminates on the flat surface representing a side of the cylindrical body of the roll.

The known axial packaging machines comprise:.

Such a packaging machine is known, for example, from <CIT>.

To obtain this axial wrapping, the roll is rotated by means of two rollers, or a belt, which support it and at the same time rotate it around the longitudinal axis thereof.

Said rotating arm, at the end of which the film distributing head is arranged, revolves around the roll which is rotated on itself, gradually unwinding the film until it is completely wound around the roll.

Generally, said rotating arm has a fixed height from the ground and the film distributing head moves vertically with respect thereto so that it assumes a central position relative to the roll.

Alternatively, said frame for resting on the ground can be of the type comprising two columns and a gantry movable vertically thereon, below which the rotating arm is rotatably associated.

At the end of the wrapping, the film is terminated by sealing it on the film already unwound and cutting it.

In packaging machines, a critical aspect not easy to solve is termination of the film which must be thermally sealed to the film already wound around the roll, at a flat side thereof, and should not have "tails", namely flapping edges of film. Said tails, which extend both from the roll and from the distributing head, are difficult to manage and dangerous both for the unwinding system and for the roll movement system, since they can be sucked in and cause malfunctioning of the respective devices.

For said purpose, the traditional packaging machines comprise:.

Said packaging machines comprise clamping means for clamping said at least one free edge of film, associated with said frame or fixed to the ground.

The film termination operations are performed as follows:.

If the sealing and cutting devices are separate from each other and geometrically distant, said operations generate two free edges of film: a first edge extends from the sealing line on the roll to the point at which the cut has been made; a second edge extends from the cutting point to the film distributing head.

Clearly said tails interfere with the subsequent logistics of the finished product.

While the first edge is not particularly bothersome, and may not even be present if the cutting means are near the sealing means, the second edge is more problematic and must be retained in order to automatically resume the winding operations, also on a new roll.

At the start of a new winding operation, the following conditions occur:.

The result is generally negative since the quantity of film just wound is not sufficient to counter the tension exerted by the distributing head and the entire film just deposited unwinds and begins to rotate.

Furthermore, even more disadvantageously, the free edge has a considerable length (equal at least to the sum of the distance between the side of the roll and the clamping means and between the latter and the film distributing head) and, if not controlled, can reach the various mechanisms of the machine with the risk of jamming.

Alternatively, during unwinding the film overcomes the clamping means which are still closed, passing above them accompanied by mechanical leads. This causes easy breakages of the film during the phase of overcoming said leads.

Obviously the main problem is management of the edge of film produced at the time of cutting, and in particular the position in which it is clamped and retained, due to the fact that said clamping means are a long way from the cutting and sealing means.

In no known packaging machine are said sealing, cutting and clamping means integrated on a single structure that moves toward and away from the side of the roll.

The object of the present invention is therefore to overcome the above negative aspects, providing a packaging machine for film-wrapping a roll of web material that correctly manages and minimizes the edge of film produced during cutting, which is efficient, practical, easy to manage and ensures rapid winding of the roll, optimizing all the wrapping operations, without wastage of film, and providing a packaged roll free from defects.

A further object of the invention is to produce a packaging machine provided with a supporting structure that integrates the functions of sealing, cutting and clamping of the film at a very limited geometric distance between the relative components, and which does not interfere with or obstruct the passage of the film distributing head.

The object of the invention is achieved by a packaging machine for film-wrapping a roll of web material comprising two flat sides, where said packaging machine comprises:.

characterized in that said first supporting structure comprises a bracket, and on board said bracket said sealing means, said cutting means and said clamping means are arranged, so as to integrate in a functional assembly all the means involved in termination of the winding of said roll with said film to clamp said free end of said free edge near said sealing line.

According to a first aspect of the invention, said bracket is reclinable and is connected to said first supporting structure by means of horizontal axis hinge constraining means, allowing said bracket to rotate in a vertical plane between two work positions.

In particular, said first supporting structure comprises actuator means for rotating said bracket around said hinge constraining means.

In a preferred embodiment variation, said first supporting structure comprises:.

Advantageously, said carriage constraining means comprise a sliding block associated with said second end of said vertical upright and a track, on which said sliding block slides, provided along said horizontal cross member.

Furthermore, said first supporting structure comprises actuator means adapted to impart a translation movement to said sliding block.

According to further aspects of the invention, said sealing means comprise a sealing bar, and said cutting means comprise a metal wire and heating means for said wire.

Advantageously, said sealing bar and said metal wire are positioned beside each other parallel to the extension of said bracket.

In a preferred variation, said clamping means comprise two slidable jaws, slidable by means of actuator means toward and away from each other, along said bracket.

In particular, said jaws are slidable along said reclinable bracket parallel to said sealing bar and said cutting wire.

Advantageously, said rotating arm rotatably associated below said gantry is symmetrical and comprises two ends, with each of which a film distributing head is associated, where said packaging machine comprises a first and second supporting structure for corresponding sealing means, cutting means and clamping means, slidable symmetrically along said gantry, each moving toward or away from a side of said roll.

The invention has numerous advantages due substantially to the presence of a compact supporting structure, which integrates and incorporates in a functional assembly the film sealing, cutting and clamping means, with minimum overall dimensions and a very limited geometrical distance between the single components.

All the sealing, cutting and clamping means are on board said reclinable bracket and therefore all move with it simultaneously.

Not only is the film sealed and cut along two lines very close to each other or substantially coinciding against the side of the roll; the only edge of film produced, between the cutting line and the film distributing head, is immediately clamped and retained at its free end, managed directly on board the reclinable bracket and is not free to flap, with the risk of interference with the subsequent winding operations.

A further advantage consists in the possibility of said reclinable bracket rotating, arranging itself horizontally at a height not interfering with the passage of the film distributing head. The rotating arm can therefore carry out several rotations while the clamping means continue to retain said edge, so as to secure the film being wound on the roll before releasing the edge which is thus incorporated in the wrapping.

In general the advantages for the entire packaging machine can be summarized as follows:.

Further characteristics and advantages of the invention will become clearer from the more detailed description provided below, with the help of the drawings that show a preferred embodiment thereof, illustrated by way of non-limiting example, in which:.

With reference to the Figures, a packaging machine <NUM> is illustrated <NUM> for wrapping with film <NUM>, preferably a polyethylene film, a roll <NUM> of web paper material having a longitudinal axis x, a cylindrical body and two flat sides <NUM>.

In general the same packaging machine <NUM> can be used for packaging all goods having a flat surface on which the film can be terminated such as, for example, in addition to rolls, also pallets or packages with parallelepipedal shape.

With particular reference to <FIG>, said packaging machine <NUM> essentially comprises:.

Said first motor means M1 comprise an electric motor and a belt drive.

Said rotating arm <NUM> is symmetrical: at a first end <NUM>' thereof the film distributing head <NUM> is associated, while at a second end <NUM>" thereof a balancing counterweight (not illustrated) is associated.

Said second motor means M2 comprise a parallel axis gearmotor and a device for the electric connection between said gantry <NUM> and said rotating arm <NUM>.

Said supporting and rolling means <NUM> for supporting and rolling said roll <NUM> comprise two tubular belts <NUM> on which the roll <NUM> lies; said tubular belts <NUM>, provided with respective longitudinal axes, arranged symmetrically relative to a vertical plane passing through said longitudinal axis x of the roll <NUM>, provide an ideal cradle for housing rolls <NUM> having different diameters.

Alternatively, said support and rolling means <NUM> can have other forms known to persons skilled in the art.

Said packaging machine <NUM> comprises a first supporting structure <NUM> on which the following are installed:.

Said first supporting structure <NUM> for said sealing means <NUM>, said cutting means <NUM> and said clamping means <NUM> is slidable along said gantry <NUM>, moving toward or away from the side <NUM> of said roll <NUM>.

With particular reference to <FIG>, said first supporting structure <NUM> comprises:.

On board said reclinable bracket <NUM> said sealing means <NUM>, said cutting means <NUM> and said clamping means <NUM> are arranged so as to integrate in a functional assembly all the means for terminating the winding of said roll <NUM>.

Said hinge constraining means <NUM> are adapted to allow said reclinable bracket <NUM> to rotate in a vertical plane between two work positions.

Said reclinable bracket <NUM> rotates substantially by <NUM>° between a vertical operating position for sealing and cutting the film against the side <NUM> of said roll and a horizontal operating position for retaining the free edge <NUM> of film <NUM> during starting of winding of the roll <NUM>.

Said carriage constraining means <NUM> comprise a sliding block <NUM> associated with said second end <NUM>" of said vertical upright <NUM> and a track <NUM>, on which said sliding block <NUM> is slidable.

Said first supporting structure <NUM> comprises actuator means <NUM> to cause the rotation of said reclinable bracket <NUM> around said hinge constraining means <NUM>, and actuator means <NUM> adapted to impart a translation movement to said sliding block <NUM>.

Said actuator means <NUM> are of linear type.

Said actuator means <NUM> are of linear type advantageously composed of a pneumatic cylinder without stem or of a linear motorized guide.

Said sealing means comprise a sealing bar <NUM>.

Said cutting means comprise a metal wire <NUM>, advantageously an electric resistance, and heating means for said wire, advantageously operating by means of electric current.

Said clamping means comprise two jaws <NUM> slidable, by means of actuator means <NUM>, toward and away from each other. Said jaws <NUM>, by closing against each other, compact the free end <NUM>' of the free edge <NUM> of film <NUM> in a butterfly shape.

Said sealing bar <NUM> and said metal wire <NUM> are positioned beside each other longitudinally to said reclinable bracket <NUM>; said jaws <NUM> are slidable along said reclinable bracket <NUM> parallel to said sealing bar <NUM> and to said cutting wire <NUM>.

As said above, in the variation illustrated, said packaging machine <NUM> comprises a single film distributing head <NUM> associated with one end <NUM>' of said rotating arm <NUM>. To avoid unbalances of the machine during rotation of the rotating arm <NUM> at high speeds, the arm is symmetrical relative to its rotation axis y and at the second free end <NUM>" a counterweight (not illustrated) is positioned in order to balance the weight of the film distributing head <NUM>.

In an alternative variation (not illustrated) particularly advantageous in operational terms, said packaging machine <NUM> comprises a first and a second film distributing head <NUM> arranged at the ends <NUM>', <NUM>" of the symmetrical rotating arm <NUM> adapted to operate simultaneously on the roll <NUM> so as to halve the wrapping times. In the same way the packaging machine <NUM> comprises a first and a second supporting structure <NUM> for corresponding sealing means <NUM>, cutting means <NUM> and clamping means <NUM>, each supporting structure <NUM> adapted to operate on the film <NUM> during unwinding from a distributing head <NUM> and on a side <NUM> of the roll <NUM>. Said supporting structures <NUM> are slidable symmetrically along said gantry <NUM>, each toward or away from a side <NUM> of said roll <NUM>.

In a particularly simplified variation of the packaging machine (not illustrated), said frame for resting on the ground is of the column type, and said rotating arm is rotatably associated with said frame at a fixed height. Said film distributing head is slidingly associated with the end of said rotating arm with mobility along a vertical axis.

With reference to <FIG>, the operation of the packaging machine <NUM> for wrapping with film <NUM> a roll <NUM> of web material according to the invention is illustrated, in particular with reference to the termination operations of the film <NUM> once the winding has been completed.

<FIG> refers to the phase of preparing the packaging machine <NUM> for the final operations for termination of the film <NUM> in which:.

<FIG> refers to the actual sealing and cutting phase of the film <NUM> in which:.

<FIG> refers to the phase of removal of the roll <NUM> just packaged and replacement thereof, on the support and rolling means <NUM>, with a new roll <NUM> to be wound.

During the roll change operations, the work phases of the packaging machine <NUM> are:.

Claim 1:
A packaging machine (<NUM>) for wrapping a roll (<NUM>) of web material, comprising two flat sides (<NUM>), by means of a film (<NUM>), where said packaging machine (<NUM>) comprises:
- a frame (<NUM>) for resting on the ground;
- a rotating arm (<NUM>) rotating about a vertical axis (y), rotatably associated with said frame (<NUM>);
- at least one film distributing head (<NUM>) associated with one end (<NUM>') of said rotating arm (<NUM>);
- unwinding means for unwinding said film (<NUM>);
- supporting and rolling means (<NUM>) for supporting and rolling said roll (<NUM>) about a longitudinal axis (x) thereof;
- sealing means (<NUM>) for sealing said film (<NUM>) being unwound against said film already wound on said roll (<NUM>) along a sealing line placed at one side (<NUM>) of said roll (<NUM>);
- cutting means (<NUM>) for cutting said film (<NUM>) adapted to interrupt the continuity thereof along said sealing line, creating a free edge (<NUM>) of said film (<NUM>) which extends from said film distributing head (<NUM>) to a free end (<NUM>');
characterised in that the machine further comprises:
- a first supporting structure (<NUM>) for supporting said sealing means (<NUM>) and said cutting means (<NUM>) slidable along said frame (<NUM>) toward or away from one side (<NUM>) of said roll (<NUM>);
- clamping means (<NUM>) for clamping said free edge (<NUM>) of film (<NUM>);
- a control unit,
wherein said first supporting structure (<NUM>) comprises a bracket (<NUM>) and said sealing means (<NUM>), said cutting means (<NUM>) and said clamping means (<NUM>) are arranged on said bracket (<NUM>), so as to integrate in a functional assembly all the means adapted for terminating winding of said roll (<NUM>) with said film (<NUM>) to clamp the free end (<NUM>') of said free edge (<NUM>) in proximity of said sealing line.