DESCRIPTION

Technical Field

The present invention relates to the machines for treating a fabric; in particular, an object of the invention is a machine for drying and shrinking a fabric, preferably, although without limitation, a knitted fabric. A further object of the invention is a method for drying and shrinking a fabric, preferably, although without limitation, a knitted fabric.

State of the Art

Nowadays, various methods and equipment are well known for continuously drying a fabric.

A machine is known, for example, comprising a large oven having a chamber where the fabric moves forwards and slides hung at the upper part on controlled rollers and hung in free folds at the lower feeding part. The fabric is slowly and gradually dried inside the chamber, full of hot air.

Another machine provides for a certain number of fluid-heated rollers on which the fabric moves continuously; the fabric partially surrounds them, and thus heats up and dries.

Moreover, a machine is known where the fabric is fed through a series of hot-air blowers, resting on one or more feeding conveyors that move it up to the exit.

At the same time, it could be important not only drying the fabric, but also finishing it, to give it dimensional stability that is important for making the finished article, giving it volume and soft handle.

Currently, a discontinuous rope method is used to have a knitted fabric with dimensional stability and soft handle, which is implemented in tumblers similar to those used in laundry.

There are also continuous rope treatments, which however have some disadvantages due to the formation of folds and knots on the fabric. In addition to this it is necessary, as however also in the discontinuous rope methods, to subject the treated fabric to a rope opening process through specific machines to extend the fabric again. Moreover, the continuous rope treatments are very expensive from an energy consumption viewpoint.

Some treatment machines provides for introducing the fabric inside chambers where it is vibrated to allow shrinking thereof. However, the resulting shrinking and voluminization of the fabric are not satisfactory.

Machines also exist that provides for passing the fabric in a chamber where it moves through water basins and vibrating rollers in which water is sprayed, so that in the chamber there is wet vapor. In this case again, the resulting shrinking and voluminization of the fabric are not satisfactory.

All the known machines are not able to achieve a satisfactory level of drying and contemporaneous shrinking and softness of the fabric.

Object and summary of the invention

The object of the invention is to provide a machine for continuously drying and shrinking fabrics, in particular, although without limitation, knitted fabrics, that is able to achieve optimum shrinking and, at the same time, optimum voluminization and soft handle of the fabric during the drying thereof.

A further important object of the invention is to provide a method for continuously treating fabrics, preferably knitted fabrics, that is able to achieve optimum shrinking and, at the same time, optimum voluminization and soft handle of the fabric during the drying thereof.

These and other objects, that will be better described below, are achieved through a machine for continuously drying and shrinking a fabric, comprising:

-a treatment chamber,

-a feeding path for continuously feeding the fabric into the treatment chamber,

-air heating means, suitable to heat and move air towards the fabric,

-a plurality of moving and drying devices for moving and drying the fabric, arranged in series along said path, inside the treatment chamber, each device comprising

either a motorized rotating drying roller provided with an inner cavity and with a cylindrical surface provided with a plurality of passages towards the inner cavity, the roller being suitable to be partially wound by the fed fabric, so that the roller, while rotating, brings the fabric with itself, or a hot air diffuser, that is operatively connected to the delivery pipe of the air heating means, and is arranged near the roller in the fabric winding area, or suction means for sucking air from the inside of the roller towards the outside of the treatment chamber, so that air coming from a respective diffuser is sucked from the space between the diffuser and the roller towards the inside of the roller, passing through the passages provided on the cylindrical surface of the roller and consequently crossing the fabric arranged on the roller, drying it,

-a vibrating basin for each pair of consecutive moving devices, on which the fabric moving between two consecutive moving devices can be deposited.

This machine allows to combine uniform and gradual drying of the fabric with shrinking and voluminization thereof, also obtaining soft handle. Conveniently, the fabric enters the machine when it is still partially wet (for example humidity i.e. moisture 20-22%); it is then dried (for instance up to humidity 0% or completely dry) uniformly along the path thereof; moreover, thanks to the vibrating basins there is a contemporaneous shrinking action on the fabric while it is no longer completely wet and not yet completely dry. The rollers arranged in series allow optimum uniform drying and, thanks to the surface distribution of the fabric on the cylindrical surface of the rollers, no defects are formed in fabric feeding direction.

The fabric is continuously fed preferably in open-width direction, i.e. not in rope direction, i.e. the fabric is distributed flat and is not wound on itself in longitudinal direction. Adequately, the fabric may be fed in open fashion (i.e. it has two side edges) or in tubular fashion (i.e. it forms a tube, i.e. it has side edges joined together).

The machine is preferably provided with control means for controlling the amount of moisture in the fabric entering the machine. Adequately, said means verify whether the moisture in the fabric is comprised between 10% and 40%, more preferably comprised between 15% and 30%, and even more preferably comprised between 18% and 25%. The moisture is measured as percentage of water mass to the weight of the dried material. The measurement is performed for example through a probe roller connected to an electronic equipment that measures the electrical resistivity of the fabric, thus determining the moisture level thereof.

Adequately, the machine is provided with an electronic device for controlling, managing and actuating the same machine. This electronic device may be suitable to control one or more of the following parameters, weight of the fabric in one or more vibrating basins, moisture of the fabric entering the machine, moisture of the fabric exiting them machine, moisture in one or more intermediate positions of the fabric feeding path, roller rotation speed, air heating temperature, temperature of the air exiting towards the diffusers, flow rate of hot air exiting the diffusers, flow rate of hot air exiting the rollers.

According to preferred embodiments, the air heating means comprise a heating space where a heating device, at least one air intake for the air entering the space, and at least one heated air delivery opening are provided; air filters are preferably provided, arranged on said air intake.

The heating device may be, for instance, a burner, and the space with the burner is thus a combustion chamber. In other embodiments, the heating device may be a steam heat exchanger or a diathermic oil heat exchanger, or a different heat exchanger, through which the air from the chamber shall pass before being moved towards the diffusers.

The heating space may be arranged inside the treatment chamber, for example below the area occupied by the rollers, or outside the main walls of the chamber, but communicating thereto.

Therefore, at least one air intake for air entering the space adequately connects the inside of the chamber with the inside of the space.

The heating means are programmed to heat air up to such a temperature comprised, preferably when exiting the diffusers, between 60°C and 120°C, preferably between 70°C and 1 10°C and more preferably between 80°C and 100°C. Temperature sensors may be provided, for example near the exit of the diffusers.

The air heating means preferably comprise pipes operatively connected, at one end, to the at least one delivery opening of the heating space and, at the other end, to respective hot air diffusers, at least one moving device (for example a sucker, a fan or the like) being provided for moving air from the space towards the diffusers.

According to preferred embodiments, the suction means suitable to suck air from the inside towards the outside of the roller comprise a discharge duct operatively connected, at an end, to the inside of the roller and, at the other end, to an exhaust duct suitable to make the air sucked by the roller exit outside the treatment chamber, at least one moving apparatus (for instance a sucker, a fan, an air extractor, a turbine or the like) being provided for moving air from the roller towards the exhaust duct. A common single exhaust duct is preferably provided for each discharge duct for discharging air from each roller; an air moving apparatus is preferably provided, associated with the common exhaust duct.

According to preferred embodiments, the suction means suitable to suck air from the inside towards the outside of the roller comprise means for varying the quantity of air sucked by the roller. These means may comprise, for example, a regulator for adjusting the speed of the rotor of the moving apparatus, or for adjusting the exit section of the discharge duct from the roller. The means for varying the quantity of air sucked by the roller comprise, for example, a partialization device, for example a partialization valve, for partializing the air exiting from the roller. One partialization device is preferably provided for each discharge duct.

According to preferred embodiments, the machine comprises means for varying the quantity of air supplied by the diffusers. These means may comprise, for example, a regulator for adjusting the speed of the rotor of the moving apparatus, or for adjusting the exit section of the inlet ducts to the diffusers.

According to preferred embodiments, the machine comprises an entrance vibrating basin arranged upstream of the first moving and drying device crossed by the fabric.

According to preferred embodiments, the machine comprises an exit vibrating basin arranged downstream of the first moving and drying device crossed by the fabric.

In the vibrating basins the fabric is adequately arranged in folds. According to preferred embodiments, upstream of each rotating roller a centering and stretching device is provided for correctly centering and stretching the fabric T on the roller.

The base configuration provides for a machine with two rollers and one intermediate vibrating basin between the two rollers (not taking into account any optional, even if preferred, entrance and exit basins).

Other preferred configurations provide for a higher number of rollers, for instance three rollers with two intermediate vibrating basins arranged between the two rollers, or four rollers with three intermediate vibrating basins, or five rollers with four intermediate vibrating basins, etc.

The higher the number of rollers, the greater the uniformity in drying as well as the greater the shrinking and voluminization.

In the preferred embodiments, the basins are one more than the rollers, the number of basins being the number of entrance basins and exit basins plus the numbers of intermediate basins arranged between the rollers.

The vibrating basins of the machine are preferably inclined from the top downwards in the fabric feeding direction.

According to preferred embodiments, inclination adjusting means are associated with one or more vibrating basins for adjusting the inclination of the respective vibrating basin; thus, by increasing or decreasing the downward inclination in the fabric feeding direction, the speed at which the folded fabric slides into the basins is increased or decreased.

According to preferred embodiments, the machine comprises means for varying the rotation of the rollers, for example by varying the rotation speed of the rotors of the motors associated with the rollers or the gear ration in case the motorization(s) of the rollers are connected to the rollers not directly but through adequate mechanisms.

According to preferred embodiments, the machine comprises a continuous fabric feeding device that can be inside and outside the treatment chamber, adequately immediately upstream of a first vibrating basin in the fabric feeding path.

According to preferred embodiments, the machine comprises a continuous fabric extraction device that an be inside and outside the feeding chamber, adequately immediately downstream of the last vibrating basin in the fabric feeding path.

According to preferred embodiments, the machine comprises means for assessing the moisture in the fabric deposited in a basin. These means preferably comprise a measuring device for measuring the weight of the fabric in a basin.

The machine according to one or more of the configurations described above comprises an operative sequence.

As mentioned, the machine is adequately provided with an electronic device for controlling, managing and actuating the same machine. In the electronic device an operative program is provided for the operation of the machine, providing for the following steps, sequentially and continuously, for each consecutive fabric portion of the continuous fabric fed to the machine: a) feeding a fabric portion to the treatment chamber, for instance through the continuous fabric feeding device for feeding the fabric to the machine, the fabric portion having moisture comprised between 10% and 40%, more preferably comprised between 15% and 30%, and even more preferably comprised between 18% and 25%,

b) vibrating the fabric portion in a vibrating basin preferably inclined from the top downwards in the fabric feeding direction,

c) making hot air pass through the fabric portion, partially winding the fabric portion on a rotating perforated roller, the temperature of the air being comprised between 60°C and 120°, preferably between 70°C and 1 10°C and more preferably between 80°C and 100°C,

d) repeating, one or more times according to the number of rollers and intermediate vibrating basins provided, the sequence step b) - step c) - step b) for the fabric portion,

e) removing the fabric portion from the treatment chamber, for example through the continuous extraction device for extracting the fabric from the machine, the residual moisture being comprised between 4% and 0%, more preferably being comprised between 2% and 0%, and even more preferably being equal to approximately 0%.

The electronic device preferably allows to adjust the quantity of hot air passing through the fabric portion.

The electronic device preferably allows to adjust the roller speed, the speed and more in general the feeding speed of the fabric through the treatment chamber, i.e. the time for passing through the chamber.

According to a further aspect the invention relates to a method for drying and shrinking a continuous fabric, comprising the following steps, sequentially and continuously, for each consecutive portion of fabric:

a) feeding a fabric portion to a drying and shrinking area, the fabric portion having moisture comprised between 10% and 40%, more preferably comprised between 15% and 30%, and even more preferably comprised between 18% and 25%,

b) vibrating the fabric portion,

c) drying the fabric portion at least partially, making hot air pass through it and preferably moving it through rotation resting on a cylindrical surface, the temperature of the air being comprised between 60°C and 120°, preferably between 70°C and 1 10°C and more preferably between 80°C and 100°C,

d) repeating, one or more times, the sequence step b), step c) step b) for the fabric portion,

a) removing the fabric portion from the drying and shrinking area, the residual moisture being comprised between 4% and 0%, more preferably being comprised between 2% and 0%, and even more preferably being equal to approximately 0%.

The method preferably comprises a step of adjusting the quantity of hot air passing through the fabric portion.

The method preferably comprises a step of adjusting the feeding speed of the fabric through the drying and shrinking area.

During vibration, the portion of fabric is preferably accumulated in folds.

Brief description of the drawings

Further characteristics and advantages of the present invention will be more apparent from the description of a preferred, although not exclusive, embodiment, illustrated by way of non-limiting example in the attached tables of drawing, wherein: figure 1 is a schematic side view of a machine according to the invention, and figure 2 shows a variant of the machine of figure 1 .

Detailed description of an embodiment of the invention

With reference to the figures, a machine for continuously drying and shrinking a fabric is indicated with number 10.

The machine comprises a treatment chamber 1 1 with walls 12, inside which a continuous feeding path is provided for the fabric T.

A plurality of alternate stations are provided along the feeding path, for vibrating the fabric and hitting it with hot air, as described below.

A continuous fabric T with a given moisture level, better specified below, is continuously fed into the chamber by means of a feeding device 13 comprising, for example, a calender with drawing rollers.

The continuous fabric T is arranged in open width (i.e. not in rope) and is preferably open (alternatively, it can be a tubular continuous fabric).

A first vibrating basin 14, also called entrance basin, is arranged immediately downstream of the feeding device 13 and at a lower height than the device, so that the fed fabric falls towards the basin 14. In the basin the fabric is accumulated in folds.

The vibrating basin 14 is inclined from the top downwards in the fabric feeding direction f.

Adjusting means, not specifically shown in the figures, are provided for regulating the inclination of the basin, so that it is possible to increase or decrease the sliding of the fabric into the basin (by combining vibration and inclination, the folds of the fabric move forwards sliding along the basin).

The vibrating basin is a basin to which vibrating means, not specifically shown in the figures, are associated, for example actuators for reciprocating motion or rotors with an eccentric constrained to, or in contact with, the basin. The vibrations of the basin allows shrinking the knitted fabric.

At the end of the basin opposite to the fabric entrance area and above the level of the same basin, a first centering and stretching device 15 is provided for correctly centering and stretching the fabric T in the next station that is constituted by a first moving and drying device 16', described below, arranged above the centering and stretching device 15.

A second vibrating basin 17, also called intermediate vibrating basin, is provided immediately downstream of the first moving and drying device 16', which is substantially analogous to the first vibrating basin 14 and which also has variable inclination.

At the end of the second vibrating basin 17 opposite to the fabric entrance area and above the level of the same basin, a second centering and stretching device 18 is provided for correctly centering and stretching the fabric T in the subsequent station that is constituted by a second moving and drying device 16", described below.

A third vibrating basin 20, also called exit vibrating basin, is provided immediately downstream of the second moving and drying device 19, which is substantially analogous to the other vibrating basins 14 and 17 and which also has variable inclination.

Downstream of the third vibrating basin 20 a continuous fabric extracting device 21 is provided, for example a drawing roller, for removing the fabric from the machine.

Each moving and drying device 16 comprises a motorized drying rotating roller 22 provided with an inner cavity 23 and with a cylindrical surface 24 provided with a plurality of passages towards the inner cavity 23, adequately in the form of through holes 25.

The fabric T coming from the centering and stretching device 15 or 18 is partially wound on the upper portion of the roller 22, so that the roller 22, when rotating, brings the fabric with itself and dries it, as it will be described below.

A hot air diffuser 26 is arranged above the roller 22 and near it in the area where the fabric is wound; the diffuser is operatively connected to the delivery pipe of air heating means 27 described below. A space 28 is provided between the diffuser 26 and the cylindrical surface 24 of the roller 22.

Suction means 29 are provided for sucking air from the inner cavity 23 of the roller 22 towards the outside of the treatment chamber 1 1 , so that the hot air coming from a respective diffuser 26 is sucked from the space 28 towards the inside of the roller 22, passing through the through holes 25 and consequently crossing the fabric T arranged on the roller, thus drying it.

The roller 22 adequately rotates on a lower cradle, covering the lower holes of the roller 22; the air is therefore sucked by the uncovered holes arranged on the upper part of the roller 22, i.e. on the part of the roller surrounded by the fabric.

The suction means 29 comprise, for example, a discharge duct 30 operatively connected, at an end, to the inner cavity 23 of the roller 22 and, at the other end, to an exhaust duct 31 suitable to make air sucked by the roller 22 exit outside the treatment chamber 1 1 . To this end, an air moving apparatus 32 is provided, for example a sucker, a fan, an air extractor, a turbine, or the like, for moving air from the roller 22 towards the exhaust duct 31 .

A common single exhaust duct 31 is preferably provided for each air discharge duct 30 for discharging air from each roller 22. A single air moving apparatus 32 is adequately provided, associated with the common exhaust duct 31 .

The suction means 29 comprise means for varying the quantity of air sucked by the roller 22. These varying means comprise, for example, a regulator for regulating the exit section of the discharge duct 30 from the roller 22, such as an air partialization device 33 for partializing air exiting from the inner cavity 23 of the roller 22, for instance a partialization valve arranged in the discharge duct 30 (one for each discharge duct).

The means for varying the quantity of air sucked by the roller 22 may comprise, alternatively or in combination with the partialization device 33 mentioned above, a regulator for regulating the speed of the rotor of the air moving apparatus 32 for moving air from the roller 22 towards the exhaust duct 31 .

The air heating means 27 comprise a heating space 34, preferably contained in the treatment chamber 1 1 , inside which the following are provided: a burner 35, an air intake 36 for the air entering the space 34, to which filters 36A are associated and which connects the inside of the chamber 1 1 and the inside of the space 34, and a heated air delivery opening 37.

Pipes 38 are operatively connected, at one end, to the delivery opening 37 and, at the other end, to respective hot air diffusers 26. An air moving device 39 (for instance a sucker, a fan, or the like) is associated with the pipes 38 for moving air from the space 34 towards the diffusers 26.

As mentioned, the machine is adequately provided with an electronic device for controlling, managing and actuating the same machine, that has not been shown in the figures for the sake of simplicity. In the electronic device an operative program is provided for the operation of the machine providing for the following steps, sequentially and continuously, for each consecutive portion of the continuous fabric T fed into the machine, taking into account that the fabric T is continuously and sequentially moved through the treatment stations indicated above, from the feeding device 13 to the extraction device 21 .

First of all, the fabric T is brought inside the machine when it is off, in a starting configuration, i.e. with the fabric in folds in the basins and wound on the rollers, for example in a quantity comprised between 40 m and 1 10 m of fabric in the machine.

Through the feeding device 13 a portion of fabric T is fed from the outside of the treatment machine into it. The entering portion of fabric has a moisture comprised between 18% and 25%, preferably comprised between approximately 20% and 22%. The machine comprises means, not shown n the figures, for controlling the moisture level in the fabric entering the machine. For assessing the moisture level, the machine may also comprise means for assessing the moisture level in one or more basins, for example a measuring device, not shown in the figures, for measuring the weight of the fabric T in the basins 14, 17, 20, or a probe roller connected to an electronic equipment measuring the electrical resistivity of the fabric T, thus determining the moisture level thereof, or any other means.

The portion of fabric fed to the machine is made vibrate in the first vibrating basin 14, where it is collected in folds.

Then, the portion of fabric T passes from the basin 14 to the first rotating roller 22, the upper portion of which is surrounded by the fabric that is thus arranged on the cylindrical surface of the roller. Here, the fabric is hit by the hot air coming from the diffuser 26.

The hot air comes from the heating space 34 where it is heated by means of the burner 35. Thanks to the air moving device 39 the air is sucked in the space through the filters and the intake 36. In the space, the air is heated by the burner 35; the air moving device 39 makes the heated air exit from the delivering opening 37 and pass through the pipes 38 up to the diffuser 26.

The operation of the burner is controlled so that the temperature of hot air exiting the diffusers is comprised between 80°C and 100°C.

From the diffuser 26 the hot air is sucked, through the air moving apparatus device 32, inside the inner cavity 23 of the roller 22 through the holes on the cylindrical surface thereof, and in this way hot air passes through the portion of fabric T on the roller.

Thanks to the apparatus 32 again, the sucked air is brought outside the chamber 1 1 through the ducts 30 and 31 .

Thanks to the depression of the fabric T in the inner cavity 23 due to air suction, the fabric remains adhering the cylindrical surface of the roller 22 and is drawn by the rotating roller 22. The rollers 22 draw the fabric into the machine.

The rollers 22 preferably rotate at a speed approximately corresponding to the overall transit speed of the fabric T through the machine (i.e. also corresponding to the speed of the fabric T entering and exiting the machine), for example a speed comprised between 7 meters/minute and 14 meters/minute, and more preferably between approximately 9 meters/minute and 1 1 meters/minute. However, the speed can be set and controlled by means of the electronic device for managing the machine.

Then, the portion of fabric T is made vibrate again and is crossed by hot air a number of times, sequentially, equal to the number of rollers provided in the machine. In this example, the portion of fabric T falls into a vibrating basin (the intermediate basin 17) where, according to what described above, it is made vibrate; it is then removed to pass through the second centering and stretching device 18 and achieve the second roller 22, where it is treated and moved according to what described above. The portion of fabric T from the second roller falls into the final vibrating basin 20, where it is made vibrate analogously to what described for the previous basins. From this basin, the portion of fabric is removed from the machine through the roller 21 , the residual moisture being preferably equal to approximately 0%. This substantially null level of moisture is adequately achieved immediately downstream of the last drying roller 22.

Obviously, the moisture level of the fabric constantly decreases before each vibrating basin.

The electronic device also allows to adjust the quantity of hot air to the diffusers, for example by varying the speed of the air moving device 39 or by varying the section of the ducts through which the hot air passes towards the diffusers, or by varying the quantity of air sucked by the rollers.

In this example only two moving and drying devices 16' and 16" are provided for moving and drying the fabric. Obviously, the machine can provide for more than two devices 16, according to the specific needs, for example four devices (16"' and 16""), with five vibrating basins (14, 17', 17", 17"', 20) as shown in figure 2.

The fabric treating potential (drying, shrinking with dimensional stability and voluminization) is mostly given by the time the fabric remains in the machine due to the load quantity on each vibrating basin, by the time the fabric remains in the machine due to the process feeding speed (i.e. the rotation speed of the rollers and the speed for feeding into and extracting from the machine), and by the temperature of air inside the treatment machine, and more in particular of air exiting from the diffusers.

Obviously, the functional sequence of the operations to which the fabric is subjected may be also carried out with a method in a machine different than that described herein.

This method for drying and shrinking a continuous fabric comprises, sequentially and continuously, for each consecutive portion of fabric:

a) feeding a fabric portion to a drying and shrinking area, the fabric portion having moisture comprised between 10% and 40%, more preferably comprised between 15% and 30%, and even more preferably comprised between 18% and 25%,

b) vibrating the fabric portion,

c) making hot air pass through the fabric portion, partially winding the fabric portion on a rotating perforated roller, the temperature of the air being comprised between 60°C and 120°, preferably between 70°C and 1 10°C and more preferably between 80°C and 100°C,

d) repeating, one or more times, the sequence step b)-step c)-step b) for the fabric portion,

a) removing the fabric portion from the drying and shrinking area, the residual moisture being comprised between 4% and 0%, more preferably being comprised between 2% and 0%, and even more preferably being equal to approximately 0%.

A step is provided of adjusting the quantity of hot air passing through the portion of fabric.

A step is provided of adjusting the continuous feeding speed of the fabric through the drying and shrinking area.

It is understood that what is illustrated purely represents possible non- limiting embodiments of the invention, which may vary in forms and arrangements without departing from the scope of the concept on which the invention is based. Any reference numerals in the appended claims are provided for the sole purpose of facilitating the reading thereof in the light of the description hereinbefore and the accompanying drawings and do not in any way limit the scope of protection.