EP3983593B1

EP3983593B1 - Method for continuous, open-width washing of fabrics

Info

Publication number: EP3983593B1
Application number: EP20753797.8A
Authority: EP
Inventors: Massimo Biancalani; Maurizio Toccafondi
Original assignee: Biancalani SRL
Current assignee: Biancalani SRL
Priority date: 2019-06-11
Filing date: 2020-06-11
Publication date: 2025-04-30
Anticipated expiration: 2040-06-11
Also published as: WO2020250177A3; ES3032329T3; CN113950548B; CN113950548A; BR112021024752A2; EP3983593C0; EP3983593A2; WO2020250177A2

Description

Technical field

The present invention relates to a method for industrial continuous, open-width washing of fabrics.

Prior art

The aforementioned wet treatments require diversified process steps, whereby very different machines have been proposed heretofore, to optimize certain types of washing processes instead of others.
A fabric washing process includes the successive steps of wetting with a solution of water and a product, mechanical rubbing to remove contaminant particles entangled in the fibers and squeezing to remove excess water and the dirt carried thereby.
The aforementioned steps are repeated until the fabric achieves the desired degree of cleaning.
In addition to the sequence of the above steps, additional characteristic aspects of the treatment have to be considered.
For example, the product that is used in the washing process (detergent, softener, etc.), which has the purpose of facilitating removal of contaminant particles, requires a minimum time of action on the fabric for optimized action and performance. Therefore, the addition of periods in which the fabric is at rest, once it has been wetted with the product, leads to a general performance improvement.
In addition to treatments that remove contaminants or dirt from the fabric, certain treatments for imparting particular characteristics to the fabric are also classified as washing processes.
One of these, the enzyme washing process, is highly complex and difficult to implement. This treatment is performed on mainly cellulose fabric and includes the addition of special enzymes to the bath, whose action tends to clean and shorten the surface fibers of the fabric. This provides a particular soft and/or worn-in feel.
The inherent complexity of enzyme washing is given by the difficulty to accurately control certain basic parameters, such as the operating temperature, the duration of treatment and the strong mechanical action. A wrong temperature might prevent the enzymes from acting properly or even "kill them" when it is too high, with long treatment times being required.
Treatment times may be adjusted substantially as desired in batch washing machines, in which a given amount, possibly a large amount of fabric, is loaded, treatment is carried out for as long as desired and the machine is unloaded by removing the treated fabric, and new fabric may be later introduced.
On the other hand, in continuous machines, fabric is continuously fed into the machine at a line speed and exits when treatment is completed. These machines provide the advantage of not requiring loading and unloading downtimes, but the overall treatment duration is limited by the length of the operating path of the fabric; while the fabric may be returned various times inside the machine, the length of the operating path of the fabric in the machine is apparently limited.
In the specific case of washing, it hardly exceeds 15 minutes treatment, whereby treatments that require longer times (e.g. enzyme washing, which typically takes 20-40 minutes) cannot be carried out.
It shall be further noted that certain washing treatments, such as the enzyme treatment, considerably improve in combination with a strong mechanical action on the fabric being treated. Since enzymes are substances that work on the surface of the fabric, the "enzyme-bound" part must be mechanically removed for a further layer of fabric to be attacked by other enzymes. In this respect, prior art continuous washing machines are not suitable to exert significant mechanical actions on the fabric being washed.
EP2845940A1 discloses a plant for continuous, open-width washing of fabrics, which plant has a longitudinally-extending treatment unit which comprises a plurality of cylinders that together define a washing path extending between the inlet and the outlet of the unit. A pair of conveyor belts, having a plurality of through openings, are supported by cylinders in part of the washing path and in part of the return path with which each of them forms a closed loop path. At least one of the cylinders is motorized and the closed loop paths share the same cylinders that define the washing path and are completely superimposed along it. The treatment unit also comprises a plurality of nozzles arranged along the entire washing path, facing the perforated belts, and connected to washing fluid sources.
Plants of the above described type both have a considerable structural complexity due to the presence of conveyor belts, rollers and cylinders, and cannot perform, as mentioned above, long-duration washing processes or treatments requiring a strong mechanical action.
In short, prior art machines for continuous, open-width washing of fabrics are structurally complex, unable to efficiently perform relatively long-duration treatments and substantially unable to combine washing with mechanical actions on the fabric being processed.
In addition to the machines intended for open-width washing of fabrics, rope treatment of fabrics is also known to greatly simplify the technology to be implemented on the machine, to generally reduce its dimensions and to avoid the problems due to the need to check that fabric can be closed on itself, turned, pleated, like in open-width treatment machines. Nevertheless, rope washing of fabrics clearly limits the ability of the treatment liquid to evenly and easily access the entire surface of the fabric to be treated. Also, certain steps of a few common types of washing processes cannot be carried out in rope form. For example, when washing after reactive printing, salts and excess dyes must be eliminated in the first steps and these steps cannot be performed in rope form, otherwise the results will not be uniform. For this reason, certain manufacturers usually combine open-width machine modules with rope machine modules.
Machines for rope washing of a fabric, having a pneumatic duct for conveying the fabric, are disclosed in EP0215745A1 and EP0312509A1 for batch washing and in WO0198576A1 for continuous washing.
WO2007054994A1 discloses a machine for rope-treatment of fabric, which machine comprises a pneumatic fabric dragging system and can be configured for washing treatments (see Fig. 5). The machine may be integrated in a treatment line with an open-width entry and an open-width exit for the fabric, which are formed by an open-width fabric feeder at the entry and a rope opener at the exit (see Fig. 6).
WO2006/021978A1 discloses a machine capable of treating an open width fabric or a fabric in rope form, with automatic conversion to switch from treating open width fabrics to treating fabrics in rope form or vice versa. The machine has at least in part a variable geometry to allow the fabric to be transferred and processed in rope or open width form. The machine has tanks suitable for enzymatic treatment of the fabric.
WO2008/120073A1 discloses a machine for treatment of web material including: a treatment chamber, a first conveying member and a second conveying member arranged so that, in use, the web is moved along a tortuous path. Washing fluid if applied by nozzles according to a pre-set sequence falls towards bottom tanks.

Disclosure of the invention

The main object of the invention is to provide a method for continuous open-width washing of fabrics that can overcome the limits of prior art continuous washing machines.
In particular, an object of the invention is to provide a method for carrying out industrial washing processes, such as washing after dyeing, washing after printing, enzyme washing and fibrillation and bleach washing, with a high throughput and without using complex and expensive modular arrangements.
Furthermore, an additional object of the invention is to provide a method that can be implemented in relatively limited spaces.
A further object is to provide a washing method that can efficiently carry out relatively long-duration treatments.
An auxiliary object of the invention is to provide a washing method that can combine the washing process with mechanical actions on the fabric being processed.
At least one of the above listed objects is substantially achieved by the method for continuous, open-width treatment of a fabric as defined in one or more of the accompanying claims.
In particular, in the method of the invention, fabric is washed continuously and fabric is driven inside the machine using a pneumatic duct (or "gun") that transfers the wet fabric being processed alternately between two accumulation tanks.
In a further aspect, with the method of the invention all the washing steps - feeding, bath, driving and removing- are carried out with the fabric in open-width form, i.e. open transverse to the direction of feed of the fabric along the operating path provided by the machine.
Also, the method of the invention affords various types of washing, in an efficient, relatively simple and inexpensive way.
With the method according to certain aspects of the invention, a great number of wetting and squeezing sequences may be performed on the fabric between the entry and the exit of the machine.
In further aspects of the method of the invention, the strength of the mechanical action on the fabric and/or the total treatment time are adjustable and can reach high values.
In a further aspect, a minimum time may be set for rest incubation of the washing products in solution on the fabric.

Brief description of the drawings

In the figures:

Figure 1 is a general perspective view a machine according to a first embodiment;
Figure 2 is a longitudinal sectional view of the machine of Fig. 1;
Figures 3.1 and 3.2 are respectively a partial perspective view and a longitudinal sectional view of one of the tanks used for accumulation of the fabric;
Figures 4.1 and 4.2 are partial sectional views of an accumulation tank according to two preferred embodiments;
Figures 5.1 and 5.2 show further embodiments of the accumulation tank;
Figure 6.1 is a perspective view of the hydraulic circuit in the machine;
Figure 6.2 is a side view of the hydraulic circuit connected to one of the accumulation tanks;
Figure 7 shows a variant embodiment of the hydraulic circuit;
Figure 8 is a general perspective view of a machine having a preferred air recirculation system.

Definitions

In the following description and in the appended claims the following technical terms will have the meaning as set forth hereinafter.
Fabric: a woven or nonwoven textile material whose longitudinal dimension (or length) is substantially greater than its transverse dimension (or width).
Open-width fabric: The term full-width fabric or open-width fabric is intended to designate a fabric lying at least transversely, i.e. lying in a substantially uncrimped form, in a direction perpendicular to its main direction of extension. In practice, the open-width fabric may be arranged flat both longitudinally and transversely or follow a predetermined path in which it can be arranged longitudinally in laps while lying in the transverse direction.
Washing or industrial washing of a fabric: The term washing or industrial washing of a fabric designates a wet treatment in which the fabric (or a portion of a fabric) being treated is wetted with a washing liquid which impregnates the fabric throughout its thickness. By way of example, the following washing treatments are considered:

Washing after printing;
Washing after dyeing;
Washing for desizing;
Preparation washing for bi-stretch fabrics or high twist yarn fabrics;
Preparation washing for combed wool;
Washing for dimensional stabilization and relaxation for viscose and blend fabrics;
Enzyme treatment;
Bleaching;
Fibrillation.

Washing liquid: a liquid comprising at least water. The washing liquid may also comprise one or more of the following additional components: soaps, enzymes, fabric treatment additives (such as softeners or else).

Embodiments of the invention

Referring to Figures 1 and 2, a machine for continuous open-width washing treatment of a fabric T, substantially comprises:

a first tank 10 and a second tank 12 for accumulation of the fabric T,
introduction means 20 for introducing the fabric T into the first tank 10 at a line speed V_L;
removing means 22 for removing the fabric T from the second tank 12 at the same line speed V_L;
a pneumatic transfer device 30, comprising at least one pneumatic duct (or "gun"), interposed between and communicating with the tanks 10,12, for repeated transfer of the fabric T from the first tank 10 to the second tank 12 and vice versa at a transfer speed V_T greater than the line speed V_L.

The machine may further comprise a liquid separator 40,42 located in front of one or both of said first and second outlet openings 32,34 of the pneumatic transfer device 30. In the examples, each liquid separator 40,42 is placed above said first or second tank 10,12 and comprises a respective one of two impact grids 40,42 placed in front of the two outlets 32,34 of the duct 30.
According to certain aspects of the invention, an irrigation device 50, 52 is placed at each outlet 32,34 of the duct 30 and comprises a plurality of nozzles arranged transverse to the fabric T, for sprinkling washing liquid on the fabric. The nozzles 50, 52 and the grids 40, 42 cover a major part of and preferably the entire width of the delivery openings 32, 34 of the transfer device.
Advantageously, the bottom 14,15 of each tank 10,12 has holes providing communication between the bottom and an underlying compartment 11,13 which is provided for feeding the washing liquid into the tanks, at the beginning of the treatment, and for collecting the liquid released from the fabric during treatment.
In particular, the bottom 14 of the tank 10 is preferably formed by a portion of sheet metal 16 having holes 17 (see Fig. 3.1.). Said portion of sheet metal 16 is arranged above the collection compartment 11 to close it and can be removed for inspection and cleaning of the compartment.
In the preferred embodiment as shown in the figures, the accumulation tanks 10,12 have a concave shape, as seen in longitudinal section (see Fig. 3.2). with the concavity facing upwards and a greater curvature in the portion between the fabric introducing/removing means 20,22 and the bottom of the tank and smaller curvature in the bottom portion.
In particular, the latter portion is advantageously formed as a chute 18,19 whose inclination to the horizontal plane gradually varying from about 60°, and preferably from about 50°, on the side of the duct 30 to zero inclination at the bottom of the tank. As better explained below, the particular shape of the tanks affords proper uniform accumulation of the fabric in regular laps F during repeated transfers between the tanks.
In order to improve the sliding movement of particularly binding (e.g. cellulosic) fabrics during accumulation, a plurality of second nozzles 24 may be provided in each tank, for delivering washing liquid under the outlet mouth of the duct 30, which is oriented as to generate a liquid cushion 26 for the fabric laps F along the chute 18,19 (see. Fig. 4.1).
Alternatively (see Fig. 4.2), a fluid cushion 80 may be obtained under the fabric laps F, by injecting liquid into the tank through holes 82 formed at different heights in the chute 18,19 and fed by underlying transverse ducts 84. With this embodiment low pressure liquid may be used, and more evenly distributed over the entire extent of the tank.
Figs. 5.1 and 5.2 show a further variant embodiment of the accumulation tanks, in which arcuated profiles 86 are provided, preferably consisting of pipes having a circular section, arranged in longitudinally parallel on the chutes 18,19 and conforming with their curvature. By decreasing the contact surface between the tank and the fabric, which mainly slides on the pipes 86, the friction between the fabric and the chute is dramatically reduced.
Advantageously, still to reduce the friction between the fabric and the tank, said arcuated profiles 86 have holes 88 at their top for receiving liquid.
At least a fan 60, a duct 62 and a two-way conveyor 64 having a flow switching valve in the upper part or in the lower part of the duct 30 are provided for introducing air into the duct 30.
Advantageously, a second fan 61, a second duct 63 and a second two-way conveyor 65 with a flow switching valve in the lower part or the upper part of the duct 30 may be provided.
The sprinkling nozzles 50,52 are supplied by a hydraulic circuit 5 (see Figs. 6.1, 6.2 and 7), which is connected to the bottom compartment 11,13 of each tank and comprises at least one pump 54 and, preferably, a filter 55 and means 56 for heating the liquid.
The hydraulic circuit may be formed with two twin parts, one for each tank, separated from each other (see Fig. 2), or may be configured (see Fig. 7) with the two accumulation tanks connected via a duct 58, to maintain the working conditions such as amount of liquid, product concentration, contaminants, temperatures, or other parameters, perfectly balanced in the two accumulation zones. Here, the treatment or washing liquid collected from the bottom of the two tanks is transferred via the pump 54 to the sprinkling nozzles 50,52 located in both tanks, to the outlets of the pneumatic duct.
The hydraulic circuit also has an inlet 59 for introduction of a first amount of a washing liquid into the tanks 10,12 at the beginning of the treatment and for replenishing of the liquid, if required, during the treatment.
For optimal stretching of the fabric , the pneumatic duct 30 is preferably formed with a length ranging from 1.5 to 3 meters.
The means for introducing/removing the fabric may consist of reels 20,22 (see Fig. 2) or pairs of squeezing rollers at the inlet and/or outlet or other means such as conveyor belts.
Advantageously, extractor hoods 70,72 for extracting air and atomized liquid may be provided above the tanks 10,12, such hoods being connected together via a duct 71 which is in turn connected to the delivery fan(s) 60,61 which feed, via a plenum 74, the pneumatic duct 30 (see Fig. 8).
A washing treatment according to the invention takes place as described below.
A first amount of washing liquid is introduced into the tanks 10,12 via the hydraulic circuit 5.
The fabric T is fed at full width, for example by means of a motor-driven reel 20, at a line speed V_L, into the first tank 10, in which it accumulates at full width and is impregnated with washing liquid. From the first tank 10 the fabric T is drawn in by the pneumatic duct 30 and is transferred at a transfer speed V_T, much higher than the line speed V_L, toward the second tank 12.
At the exit of the duct 30, the fabric T impacts the impact grid 42 placed in front of it. This will reduce the speed of the fabric and will cause it to fall into the second tank 12, in which, due to the particular curvature, the fabric will accumulated in small regular laps, partially superimposed, along the entire extent of the chute 19.
In the second accumulation tank 12, the fabric remains for the time required for all the fabric in the first accumulation tank 10, to be transferred to the second tank. In the meantime, the fabric is exposed to the continuous action of the jets of the mixture of water and treatment product that comes out of the nozzles 50,52.
When the fabric has been completely transferred to the second accumulation tank 12, the direction of the air flow inside the pneumatic duct 30 will be reversed by the two-way conveyors 64,65. As a result, the fabric is drawn from the second tank 12 toward the first tank 10.
While being transferred in the reverse direction, the fabric will hit the impact grid 40 in the first tank 10 and will accumulate therein in the same manner as described above, the tanks 10,12 having a mirror-like arrangement.
While the amount of fabric initially loaded into the machine is being repeatedly carried back and forth between the first and second tanks, new fabric is continuously introduced into the first tank 10 via the reel 20 and treated fabric is removed, still continuously at a speed V_L from the second tank 12, for example via a second motor-driven reel 22.
Using the hydraulic circuit 5, the washing liquid is collected from the bottom compartments 11,13 of the tanks and is pumped to the sprinkling nozzles 50,52 in the upper part of the tank, at the outlets of the pneumatic duct 30.
As mentioned above, the nozzles sprinkle the washing liquid directly above the fabric, which is thus kept constantly under the continuous action of the bath, even during the time in which it is still inside each of the two accumulation tanks.
At the end of the washing cycle the liquid that has been used can be removed from the machine, for example via a drain at the base of each tank 10,12.
According to the invention, the line speed V_L is selected as a function of the amount of fabric that is being or is to be loaded into the machine and the total washing time required. Then, the transfer speed (V_T) may be set to determine the number of back- and-forth cycles in the duct and thus indirectly determine the desired rest time of the fabric in each tank, known as relaxation time. According to the invention the transfer speed (V_T) is at least 5 times greater than the line speed (V_L).
Advantageously, for an industrially satisfactory washing process, the method of the invention provides, optionally in combination, one or more of the following steps:

inserting large amounts of fabric into a single accumulation tank, at least 300 meters per tank;
maintaining the fabric at full width, with substantially regular laps;
imparting a transfer speed V_T from one tank to another of at least 5 to 10 times the line speed V_L.

This will afford a good overall throughput of the machine, with a generally high fabric treatment time, as required for example in enzyme treatments.
In addition, the condition V_T >> V_L can provide a large number of wetting and squeezing sequences on the fabric between the entry and the exit of the machine without requiring the fabric to stay still in the same position for too long and possibly create defects in the folding areas.
Also, the large amount of fabric in the tanks and the high transfer speed V_T will allow a relaxation time for the fabric in the bath to be set during accumulation, to obtain a desired incubation time for the products.
Finally, the repeated impacts of the fabric on the grids will cause an effective mechanical action.
Therefore, the fabric will move from a wet relaxed state in the tanks 10,12 to a fast driven state inside the duct (with V_T 100 - 300 m/min and an air velocity typically of 200 - 600 m/min), which will cause a very high acceleration, thereby causing atomization of the surface layers of the impregnation liquid.
At the exit of the duct, the fabric impacts the grid in front of the mouth of the duct at high speed. Here, the fabric is compacted by the impact and is thus squeezed, thereby releasing a large amount of liquid.
Then, the above described steps are repeated several times, with the direction of the airstream being reversed inside the transfer duct.
With a method according to the present invention, in which the fabric moves at full width (i.e. open-width), the above described steps affect the entire width of the fabric.
This does not occur in machines for rope washing of fabrics, in which the liquid entrapped in the rope is only partially drained.
The particular curvature of the accumulation tanks, and especially the chute portion thereof, allows large amounts of regularly arranged fabric to be introduced therein and can withstand the force required with the fabric drawn by the duct, to be transferred to the opposite tank. Thus, the differentiated curvature (with a greater slope in the upper part of the tank close to the duct and a smaller slope in the lower part) causes accumulation in regular laps, with the ones placed at a lower level slowly sliding toward the bottom of the tank without winding into skeins and leaving room for the new ones that will be deposited above. This is particularly advantageous for washing treatments in which, if the fabric is not regularly lapped, defects and inhomogeneities may occur.
Uniform fabric lapping also reduces friction when the fabric is drawn by the duct, which translates into high transfer speeds.
In order to further reduce friction between the fabric and the surface of the tank, as mentioned above, the method of the invention includes the additional step of sprinkling a water film on the surface of the tank to form a cushion underneath the fabric laps. An additional squeezing step - which is carried out by suitable pairs of squeezing rollers - may be carried out at the outlet of and/or at the inlet of the machine, with the advantage of reducing the consumption of fluid and products dissolved therein.
Mechanical squeezing at the outlet of the second accumulation tank also provides the advantage of significantly reducing the amount of liquid inside the fabric, if additional drying steps are to be carried out by continuously connected machines for open-width drying, such as, for example, free, stenter, or tumbler dryers.
On the other hand, inlet squeezing is useful if the fabric comes from preparation steps in which it has absorbed substances that are not suitable for the type of washing to be carried out.
As the fabric is being washed, exhaust air from the duct is channeled outside or (see Fig. 8) advantageously returned to the delivery fan.
Thus, when the duct injects air in one direction, i.e. toward an accumulation tank, there is no need to cause exhaust air to escape outside, because air is channeled by the overlying extraction hood toward the opposite accumulation tank, to compensate for the negative pressure created in this second tank. As a result, no exhaust air is ejected outside, which provides the double advantage of not consuming the liquid bath, that would be inevitably partly discharged with air, due to atomization occurring in exhaust air, and avoiding the use of complex arrangements for filtering and removing suspended matter in exhaust air.

CONTROL UNIT

The machine and method as described herein use at least one control unit CU for controlling the various operating conditions implemented by the machine as it carried out the washing method.
Namely, the control unit is communicatively connected with the above described mechanical or pneumatic drive means and with the various active parts of the hydraulic circuit as well as with all the sensors located in the machine and/or used in the above described method.
The control unit may be a single unit or may be composed of a plurality of distinct control units based on the design choices and operating requirements.
The term control unit is intended to designate an electronic component which may comprise at least one of: a digital processor (CPU), an analog circuit, or a combination of one or more digital processors and one or more analog circuits. The control unit may be "configured" or "programmed" to perform certain steps: this may be achieved in practice by any means that is able to configure or program the control unit. For example, in the case of a control unit comprising one or more CPUs and one or more memories, one or more programs may be stored in appropriate memory banks connected to the CPU/s; the program/s contain instructions that, when executed by the CPU/s, program or configure the control unit to perform the operations as described herein with respect to the control unit. Alternatively, if the control unit is or comprises analog circuitry, then the control unit circuit may be designed to include circuitry that is configured, in operation, to process electric signals to perform the steps associated with the control unit.

WASHING EXAMPLE

A practical example of operation of the machine and method as described above and claimed below is now provided.
The first tank is loaded with 400 meters of fabric. The treatment time is set to 10 minutes. Then, the machine or operator determines a line speed of 400/10=40 meters/minute.
The power of the pneumatic duct is set to a level corresponding to a fabric transfer speed of 200 meters/minute inside the duct; therefore, in 10 minutes' treatment, with 400 meters of fabric in the tank, 200 meters/minute transfer speed in the duct, it will take 400/200=2 minutes to transfer the fabric from one tank to another. Therefore, about 10/2=5 wetting and "wring out" cycles are executed in 10 minutes, with 5 fabric relaxation periods in the tank lasting about 2 minutes each, which provides efficient washing in very short times and with very small machine dimensions.
In a further example in which the machine is used with enzyme-containing washing liquid and with a fabric load of 400 meters the washing process may be carried out with an efficient enzyme treatment in 20 minutes only, i.e. at a line speed V_L of 20 meters/minute. Without being bound by any theory, the ability to carry out a quick and efficient enzyme treatment is believed to be obtained by constant maintenance of fabric at full width, and by reciprocating pneumatic movement, which tends to "open" the fabric for easy liquid penetration and effective enzyme action.

Claims

A method for continuous open-width washing of a fabric (T), comprising the steps of:
- controlling continuous introduction of the fabric (T) into a first tank (10) of a washing machine containing washing liquid wherein, as the fabric is being introduced into the first tank it is constantly maintained in open-width,

- controlling alternate pneumatic transfer of the fabric from the first tank (10) to a second tank (12) of the washing machine and vice versa, said alternate transfer occurring a plurality of times with the fabric (T) still maintained in open-width,

- controlling continuous removal of fabric from the second tank (12) containing washing liquid wherein, as the fabric is being removed from the second tank it is constantly maintained in open-width,

wherein the pneumatic transfer from the first tank to the second tank and vice versa occurs using at least one pneumatic transfer device (30) of the washing machine that imparts a transfer speed (V_T) to the fabric from the first tank to the second tank and vice versa that is higher than the introduction speed (V_L) with which the fabric is introduced into the first tank and the removal speed (V_L) with which the fabric is removed from the second tank,

characterised in that

the method includes a step of wringing out the fabric that comes out of the pneumatic transfer device (30) before accumulation in the first or the second tank, in that the introduction speed and the removal speed are equal and constant and define the line speed (V_L) of the washing machine, and in that the transfer speed (V_T) is at least 5 times greater than the line speed (V_L).
A method as claimed in claim 1, wherein the transfer speed (V_T) is 5 to 10 times greater than the line speed (V_L).
A method as claimed in any of the preceding claims, wherein at least one longitudinal section of the fabric is accumulated in the first tank and wetted in that state to complete impregnation with the washing liquid and wherein said at least one longitudinal section of the fabric is later accumulated in the second tank and wetted in that state to complete impregnation with the washing liquid.
A method as claimed in any of the preceding claims, wherein the step of wringing out the fabric is obtained by causing the fabric to hit against impact grids (40,42).
A method as claimed in any of the preceding claims, wherein it includes a respective step of sprinkling washing liquid on the fabric that comes out of the pneumatic transfer device (30) before accumulation in the first tank or the second tank.
A method as claimed in claim 5, wherein the step of sprinkling washing liquid is carried out before the step of wringing out.
A method as claimed in claim 5 or 6, wherein the step of sprinkling is carried out by direct sprinkling on a surface of the fabric that faces upwards as it comes out of the pneumatic transfer device.
A method as claimed in any of the preceding claims when combined with claim 3, wherein, as the open width fabric accumulates, it forms a plurality of regular loops (F) in each of said first and second tanks.
A method as claimed in claim 8, wherein a liquid cushion is formed under the fabric accumulating in said first and/or said second tanks (10, 12), with the liquid that has been fed from the bottom of said first and/or said second tanks.
A method as claimed in claim 8 or 9, wherein said step of wetting the fabric (T) in the first or the second tank comprises sprinkling washing liquid on the top side of the fabric and injecting washing liquid into said tanks (10, 12) beneath the loops (F) being formed.
A method as claimed in any of the preceding claims, comprising a step of drawing in air and moisture from above said first and said second tanks (10, 12) and feeding such air and moisture to the pneumatic transfer device.
A method as claimed in any of the preceding claims, wherein the amount of fabric that is fed to the first tank at the beginning of the washing process and before the alternate pneumatic transfer steps is selected according to at least one of the total washing time and the line speed (V_L) with which the fabric is fed during washing.