The present invention relates to a mercerization machine.

Mercerization is an industrial process to which yarns (and textile products in general) are subjected to provide them with improved mechanical and aesthetic qualities.

In greater detail, mercerization is carried out by immersing the yarns or fabrics in chemical solutions such as to give them improved aesthetic and/or mechanical characteristics.

By way of example, mercerization processes are carried out using solutions of caustic soda, of liquid ammonia or of other substances.

Yarn mercerization machines are known comprising two handling rolls on which the yarns are rested in the form of previously prepared skeins.

The handling rolls are mutually parallel and move the yarn to enable the successive treatment steps to take place.

In detail, only one of the rolls is motorized, the other being maintained idle.

To enable the yarn to move, this has to be maintained in a state of adequate tension. In this respect, at least one of the handling rolls is provided with a shoe which, associated with a rectilinear guide, enables the roll to vary its distance from the other roll.

In this manner, the tension of the yarn wrapped about the rolls can be regulated.

It should be noted that the skein is formed by superposing yarn turns one on another. In other words, the skein presents more inward yarns on which more outward yarns are superposed.

As a disadvantage, when the skein is disposed about the handling rolls and these are withdrawn from each other to maintain the yarn under tensions, a non-uniform tension acts on the yarn. In fact, a greater tension acts on those yarn portions more inwardly disposed than on those yarn portions more outwardly disposed.

The non-uniformity of the tension acting on the different yarn portions causes a non-uniform effect on the mercerization treatment in that the penetration of the utilized chemical solution into the textile fibres is also influenced by the tension. The yarn treated in this manner presents an undesirable non-uniform appearance.

It should be noted that this non-uniformity is well visible even in the finished product, especially in certain types of manufacture.

In this context, the technical aim at the base of the present invention is to propose a yarn mercerization machine which overcomes the aforestated drawback of the known art.

A particular object of the present invention is to provide a yarn mercerization machine which enables the yarn to undergo uniform mercerization treatment. The stated technical aim and the specified object are substantially attained by a machine for yarn mercerization comprising the technical characteristics highlighted in one or more of the accompanying claims.

Further characteristics and advantages of the present invention will be more apparent from the indicative and therefore non-limitative description of a preferred but non-exclusive embodiment of a machine for yarn mercerization, as illustrated in the accompanying drawings, in which:

Figure 1 is a perspective view of a yarn mercerization machine in accordance with the present invention, shown partially in section to better highlight certain components;

Figure 2 is a perspective view of a detail of the machine of Figure 1 in a first operative step; and Figure 3 is a perspective view of the detail of Figure 2 in a second operative step.

With reference to the accompanying figures, the reference numeral 1 indicates overall a machine for yarn mercerization, in accordance with the present invention.

The machine 1 comprises a support structure 2 and a handling member 3 for the yarn F connected to the support structure 2.

The handling member comprises two handling rolls 4, connected to the support structure 2, and about which the yarn "F" is mounted wound into a previously prepared skein.

The handling rolls 4 are disposed mutually parallel. In accordance with that illustrated, the handling rolls 4 are disposed one above the other in a substantially vertical plane.

Preferably, only one of the handling rolls 4 is motorized. The other handling roll 4 is idle.

A dispensing device 5 dispenses a predetermined quantity of a working chemical solution required for the mercerization treatment. By way of example, this working solution is a caustic soda solution.

The dispensing device 5 comprises a conduit 6 which extends parallel to the handling rolls 4.

The conduit 6 is disposed to correspond with a trajectory followed by the moving yarn "F". The conduit 6 presents a plurality of equidistant dispensing nozzles 7 to spray the working solution onto the yarn "F".

The machine 1 also comprises a squeezing member 8 for extracting an excess quantity of the solution from the yarn "F".

In greater detail, the squeezing member 8 is associated with one of the handling rolls 4. In accordance with that illustrated, the squeezing member 8 is associated with the lower handling roll 4.

The squeezing member 8 comprises a squeezing roller 9 shiftable between a non-operative position (Figure 2) in which it lies spaced from the handling roll 4 and an operative position (Figure 1 ) in which it lies in contact with the handling roll 4 to press the yarn "F" against the handling roll 4 and extract any excess solution quantity.

The squeezing member 8 comprises a rotation shaft 10 connected to a motor, not shown, to rotate it about its longitudinal axis. This longitudinal axis is parallel to the handling roll 4. Two levers 1 1 are fixed, in proximity to their first ends 1 1 a, to the opposite ends of the rotation shaft 10.

The levers 1 1 are perpendicular to the rotation shaft 10 and are mutually parallel.

The squeezing roller 9 is connected to the second ends 1 1 b of the levers 1 1 such that its rotation axis is parallel to the handling rolls 4.

Rotation of the shaft 10 hence determines the described movement of the squeezing roller 9 along a circular arc trajectory.

The machine 1 also comprises a tank 26 for collecting that dispensed solution which is not absorbed.

The tank 26 is positioned to correspond with the lower handling roll 4 and at least partially wraps it.

In this manner, the solution collects in the tank 26 and the moving yarn "F" transits within the tank 26, further absorbing the working solution.

The tank 26 rotates about an axis parallel to the handling rolls 4 between an operative position (Figure 3) in which it lies close to the lower handling roll 4 to collect the working solution and enable immersion of the yarn "F", and a non- operative position (Figure 2) distant from the lower handling roll 4 in which it discharges the working solution. In alternative embodiments, the tank is fixed and integral with the support structure 2.

According to the present invention, the machine 1 also comprises a tensioning device 12 separate from the handling member 3 and acting on the yarn "F" to maintain it under tension.

The tensioning device 12 is operatively disposed between the handling rolls 4 of the handling member 3.

As illustrated, the tensioning device 12 comprises a tensioning roller 13 movable to approach and/or withdraw from the handling rolls 4.

In greater detail, the tensioning roller 13 is movable between an operative position (Figure 3) in which it is close to the handling rolls 4 and a non-operative position (Figure 2) in which it is distant from handling rolls 4.

In other words, when the tensioning roller 13 is in the operative position, it lies between the handling rolls 4, i.e. within the space between them.

When the tensioning roller 13 is in the non-operative position, it lies outside the space between the handling rolls 4.

When in the operative position, the tensioning roller 13 urges the yarn "F" into the space defined between the handling rolls 4. In this manner it increases its path length, so increasing the tension of the yarn "F".

Advantageously, those yarn portions "F" which lie on the inner side of the handling rolls 4 instead lie on the outer side of the tensioning roller.

Likewise those yarn portions "F" which lie on the outer side of the handling rolls 4 instead lie on the inner side of the tensioning roller.

In this manner, the non-uniformity in the tension acting on the yarn "F" is compensated by causing it to pass about the tensioning roller 13. Consequently, the non-uniformity in the effect of the mercerization treatment is also compensated. The tensioning device 12 also comprises manoeuvring means 14 for the tensioning roller 13 which enable it to move between an operative position and a non-operative position along a determined trajectory.

According to that illustrated, this trajectory is a circular arc. During this movement, the rotation axis of the tensioning roller 13 is maintained parallel to the handling rolls 4.

In detail, the manoeuvring means 14 comprise a manoeuvring shaft 15 connected to a motor, not shown, to rotate about its longitudinal axis. This longitudinal axis is parallel to the handling rolls 4. Two bars 16 are fixed, in proximity to their first ends 16a, to the opposite ends of the manoeuvring shaft 15.

The bars 16 are perpendicular to the manoeuvring shaft 15 and are mutually parallel.

The tensioning roller 13 is connected to the second ends 16b of the bars 16 such that its rotation axis is parallel to the handling rolls 4.

Rotation of the manoeuvring shaft 15 hence determines the described movement of the tensioning roller 13 along the circular arc trajectory.

Advantageously, the length of the tensioning roller 13 is equal to the length of the handling rolls 4.

According to a first embodiment, the distance between the handling rolls 4 is fixed and the tension is regulated only by the tensioning device 12.

In a second embodiment, the distance between the handling rolls 4 is adjustable such as to be able to regulate the tension of the yarn "F" in combination with the tensioning device 12. In this respect, eccentric regulator means (not shown) act on one of the handling rolls 4 to vary its distance from the other.

The machine 1 can also comprise a drying device 17 acting on the yarn "F" to dry it on termination of the mercerization treatment.

The drying device 17 is optional and is not indispensable.

In accordance with that illustrated, the drying device 17 comprises a heatable drying roller 18 movable towards and /or away from the handling rolls 4.

In greater detail, the drying roller 18 is movable between an operative position in which it is close to the handling rolls 4 and a non- operative position in which it is distant from the handling rolls 4.

In other words, when the tensioning roller 13 is in the operative position, it intercepts the path of the moving yarn "F" to enter into contact therewith and dry it.

The tensioning device 12 also comprises displacement means 19 for the drying roller 18 which enable it to be shifted between the operative position and the non- operative position along a determined trajectory.

In accordance with that illustrated, said trajectory is a circular arc. During this movement, the rotation axis of the drying roller 18 is maintained parallel to the handling rolls 4.

In detail, the displacement means 19 comprise a displacement shaft 20 connected to a motor, not shown, to rotate about its longitudinal axis. This longitudinal axis is parallel to the handling rolls 4. Two bars 21 are fixed, in proximity to their first ends 21 a, to the opposite ends of the displacement shaft 20.

The bars 21 are perpendicular to the displacement shaft 20 and are mutually parallel.

The drying roller 18 is connected to the second ends 21 b of the bars 21 such that its rotation axis is parallel to the handling rolls 4.

Rotation of the displacement shaft 20 hence determines the described movement of the drying roller 18 along the circular arc trajectory. By way of example, the drying roller 18 can be heated by a flow of steam introduced into the cavity defined by the drying roller 18.

The machine 1 also comprises at least one box enclosure 22 defining a working chamber in which the handling member 3 and the tensioning device 12 are housed.

The dispense device 5 and the squeezing member 8 are also contained in the box enclosure 22.

The box enclosure 22 is fixed to the support structure 2. The box enclosure 22 comprises a lateral wall 23 and a rear wall 24 fixed to the lateral wall 23.

The handling rolls 4 emerge perpendicular from the rear wall 24.

The rotation shaft 10 also emerges perpendicular from the rear wall 24.

The manoeuvring shaft 14 also emerges perpendicular from the rear wall 24.

The displacement shaft 19 also emerges perpendicular from the rear wall 24.

The box enclosure 22 comprises a reclosable lid 25 opposite the rear wall 24. As shown, the machine 1 comprises two separate box enclosures 22 closed by single lid 25. Respective handling members 3, dispensing devices 5, squeezing members 8 and tensioning devices 12 are disposed in each box enclosure 22.

Advantageously, the lateral wall 21 is slidingly associated with the support structure 2 such that it can separate from the rear wall 24. By way of example, the lateral wall 23 is mounted on guides (not shown) fixed to the support structure 2.

This provides easy access to the interior of the machine 1 such that cleaning and/or maintenance operations can be carried out.

The described invention attains the proposed objects. In this respect, the use of a tensioning device separate from the handling member enables the effect of the mercerization treatment on the entire enhanced yarn "F" to be made uniform. This allows too to manufacture textile products which do not have aesthetic and structural defects due to said non-uniformity.