PLANT FOR WASHING FABRIC RIBBONS AND RELATED WASHING METHOD

Description

PLANT FOR WASHING FABRIC RIBBONS AND RELATED MATERIALS WASHING METHOD TECHNICAL FIELD The present invention relates to the washing of fabrics after their processes 5 weaving and printing industries, and more specifically a plant and a related method for washing fabrics in the modes known in the industry as “continuous”, “open” or tubular, which respectively indicate the fact that ribbons of fabric pass through a washing system from entrance to exit completely extended in the direction of the length. 10 BACKGROUND In industrial weaving processes, washing is necessary to eliminate stains from fabrics. raw or semi-finished products, impurities such as weaving residues, as well as products chemicals such as caustic soda and bleaching products. In the case of removing oils from weaving washing is more intense and requires specific solvents, which is why we speak 15 generally of “purge”. Washing and purging are generally performed before treatments. heat setting to avoid the oxidation of the oil present on the fibres of a fabric and the their consequent yellowing. Well-known fabric washing systems comprise one or more washing units in which 20 inside there are tanks intended to contain washing and cleaning liquids rinsing. Rotating rollers or cylinders are mounted inside the washing units which define a washing path for a fabric ribbon from an input to an outlet of the washing unit itself. Washing is done with liquids such as mixtures of water with detergents, soaps and / or 25 solvents, such as limonene, or water alone at temperatures between 20°C and 99°C. Washing a fabric can be done by immersion in liquids of washing, typically first in tubs containing mixtures of water with detergents, soaps and / or solvents and then in tanks containing only water for rinsing operations, or for spraying by means of jets delivered by slotted and / or equipped spray bars 30 nozzles that are arranged along the washing path. Also known are systems of washing systems that use combinations of immersion tanks and spray bars. The Italian patent 102013902142642 describes a machine for continuously purging a fabric tape comprising a washing tank suitable for containing a washing liquid washing and means for heating the latter. The machine also includes a plurality of rollers that define a washing path along which it is transported 5 a fabric belt and sprayers arranged along the washing path. The sprayers sprayers comprise first nozzles configured to emit respective jets fan that covers the first face of the fabric ribbon along its entire width without overlapping, as well as second nozzles arranged on the opposite side of the first nozzles with respect to the washing path so as to emit respective fan jets on a 10 second face of the fabric ribbon opposite to the first face. Like the first nozzles, the second nozzles are also configured to emit fan jets that cover the second face of the fabric ribbon along its entire width without overlapping. The first and second nozzles are arranged so as to direct their respective fan jets on the same area of ​​the fabric ribbon in transit, so as to cancel the resulting 15 of the forces directed perpendicularly to it without resorting to support rollers. Italian patent 102013902188808 describes a system for washing fabrics in continuous and open modes comprising at least one treatment unit in the which are arranged a plurality of cylinders that define a washing path from an input to an output. The treatment unit comprises a first and a second 20 perforated handling surfaces configured to receive between them a sandwich a fabric tape to be treated. The handling surfaces are supported by a set of cylinders with which they form a closed ring path. Similarly to the Italian patent 102013902142642, the treatment unit comprises furthermore a plurality of first and second nozzles arranged along the entire washing path 25 and facing the perforated handling surfaces to dispense washing fluids against the opposite faces of the sandwich-like tissue they transport. The fluids of washing are supplied at pressures between 0.5 and 3 bar with flow rates between 20,000 and 40,000 litres / hour per linear metre of fabric in the direction of its width. Thanks to the arrangement of the nozzles and the high pressures and flow rates of the fluids 30 wash, you can minimize the problems of stretching and creasing in the fabric along its washing path. Despite the availability of machines and methods for washing and purifying fabrics in continuous and open modes there is still a need to improve the processes washing and related systems both from the point of view of effectiveness in removing impurities, both in terms of processing speed. It is also strongly 5 felt the need to minimize the risks of tissue damage caused by the forces exerted by relatively high pressure washing liquids sprayed from the nozzles, while maintaining the same washing effectiveness, as well as the need to reduce further the energy consumed to heat the washing liquid to a suitable temperature to effectively remove oils and chemicals present on the 10 fabric ribbons to wash. SUMMARY These objectives are at least partially achieved with a washing plant for the washing of fabric ribbons in continuous, open or tubular mode as defined in the attached claims. The system allows for the effective washing of belts 15 fabric also spraying washing liquid at reduced pressure and kept at lower temperatures because it includes at least one ultrasonic generator arranged in the washing tank so as to be at least partially submerged by the washing liquid washing and so as to generate ultrasonic sound waves directed against one face of the fabric ribbon in transit immersed in the washing liquid contained in the tank 20 wash. This disclosure further provides a method of washing fabric webs in continuous and open mode, implementable with the system described above, which It involves washing or purging fabric ribbons through the following operations: fill the wash tub with washing liquid so that it is submerged 25 at least partially the ultrasonic generator of the system; deliver jets of washing liquid towards opposite sides of a fabric ribbon in transit along the system's washing path; generate ultrasonic sound waves directed against at least one face of the tape fabric in transit immersed in the washing liquid contained in the washing tub. 30 Further embodiments are defined in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a side section view schematically showing a unit of washing the car wash system according to this disclosure. DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS With reference to the figure, a system for washing fabrics in the following modes: 5 continuous and open is overall indicated with the reference number 100. The washing system 100 comprises in a known manner at least one washing unit 110 inside which are housed two tanks arranged in series in one direction of longitudinal processing schematically indicated by an arrow L. These tanks are respectively a washing tank 111 intended to contain a 10 washing liquid, for example a solution of water and limonene, and a tub of rinse 112, intended to contain a rinse liquid, e.g. water. In figure 1 the liquid levels in each tank are schematically indicated in dotted lines. basin. Inside the washing unit 110 there are also housed a plurality of cylinders 113 15 rotating around their own axis which together define a path of washing for a fabric ribbon F, which extends from an input 116 to an output 117 of the washing unit 110 itself. In the illustrated embodiment, two sets of cylinders are shown, in particular four cylinders 113 arranged in correspondence with the washing tank 111 and four 20 cylinders 113 arranged in correspondence with the rinsing tank 112. To allow the passage of the fabric tape F through the washing unit 110, at least some of the cylinders are motorized. Preferably all cylinders are motorized to minimize any rubbing problems with the belt tissue in transit, which can cause unwanted stretching. 25 As shown in figure 1, with respect to a vertical direction V perpendicular to the longitudinal direction L, one cylinder of each set is placed in proximity of the bottom of the respective tank, therefore in an operating condition of the system 100 it works immersed in the washing or rinsing liquid, while the other cylinders are spaced from it and are located outside the washing liquid bath and the liquid 30 of rinsing in an operating condition of the plant. It will be understood that this configuration of the washing unit 110 allows in a known way to carry out the washing of a fabric ribbon by immersion in tanks 111, 112. In other words, the arrangement of the cylinders is such that the washing path, shown schematically in dotted line, develops partly outside of tanks 111, 112 and partly inside of them. 5 In the embodiment illustrated in the figures, the cylinders 113 intended to work in the washing tank 111 immersed in the washing liquid are two, allowing for lengthen the immersion path of the fabric tape leaving a space between the portion of fabric that enters the washing tub 11 and the portion of fabric that exits it he's leaving. 10 The washing liquids feeding into tanks 111, 112 are maintained at the temperature desired by means of appropriate heating means, for example serpentine pipes 118, 119. More generally, the temperature of the washing and rinsing liquids is determined by the type of detergents, soaps and / or solvents used and by the type of impurities which must be removed. The washing and rinsing liquids are made 15 recirculate in tanks 111, 112 after purification. The system 100 also comprises a plurality of spraying means 120 arranged along the washing path in the sections above tanks 111, 112, so that a fabric tape F can be treated both by spraying and by immersion. The spraying means 120 comprise in a known manner a plurality of 20 spray bars connected to the washing unit 110 transversally to the path of washing, therefore having their respective axes substantially parallel to those of the cylinders, and comprising respective nozzles, or alternatively slits, configured to direct the jets of liquid against opposite sides of the fabric tape. The washing unit illustrated is particularly suitable for washing or purging 25 of thin lightweight fabrics that are more easily damaged when spraying liquid of high pressure washing against them, because it includes at least one generator of ultrasound 114, 115, arranged in the washing tank 111 so as to be at least partially submerged by the washing liquid and so as to generate sound waves at ultrasound directed against at least one face of the fabric strip immersed in the liquid 30 wash. Tests carried out by the Applicant have shown that when the washing nozzles 120 they spray liquid at relatively low pressure, they have a mainly superficial, therefore, to clean the fabric in depth, it is necessary to increase the liquid pressure. In particular, fabrics such as cotton and lycra and fabrics in 5 Cotton and polyester, as well as non-woven fabrics, tend to absorb moisture deeply products that must be removed by washing or scouring. Consequently, currently These fabrics can only be cleaned effectively with jets of cleaning liquid. washing at relatively high pressure and keeping the washing liquid in the tank of washing 111 at a temperature of approximately 90°C. Thanks to the washing system of the 10 this disclosure, it is possible to reduce the pressure of the washing liquid jets limiting their effect to a substantially superficial cleaning action, while the deep cleaning in the tissue is entrusted to at least one 114 ultrasonic generator, 115, immersed in the washing tank 111 and which generates microbubbles which, when they collapse on contact with the fabric, removing dirt. 15 An advantage therefore of using this technique in combination with the use of nozzles 120 that spray pressure washing water consists in the fact that in the system 100 of the present disclosure the pressure of the sprayed washing water can be lowered to protect the fabrics from mechanical damage, while cleaning ultrasound, carried out by immersion in the washing tank 111, allows for 20 clean the fabric tape thoroughly. Thanks to this synergistic action, a clean fabric that has been subjected to less mechanical stress than takes place in 100 known washing plants, where the deep cleaning of the fabric is entrusted to relatively high pressure washing water jets. To perform an ultrasonic cleaning, it is important to limit the maximum temperature 25 of the washing liquid so that it does not exceed 70°C, preferably between 60°C and 65°C, because ultrasound must create micro bubbles by cavitation when the ultrasound impacts against the fabric to be washed, so you cannot have a bath of washing or purging at a higher temperature. This is an additional advantage because it allows you to reduce the temperature of the washing liquid, saving energy, 30 as it is no longer necessary to heat the washing liquid to a temperature between 85°C and 90°C, as is currently the case for certain fabrics, in order to be able to remove them in a safe manner effective oil from fabric tape F. According to an aspect illustrated in the attached exemplary figure 1, the system of washing comprises two ultrasonic generators 114, 115, arranged in the tank 5 washing so as to be at least partially submerged by the washing liquid and in so as to generate ultrasonic sound waves directed in the same direction against faces opposite of said fabric ribbon immersed in said washing liquid. In one aspect, the ultrasonic generators 114, 115 are configured so as to generate ultrasound at a frequency not less than 20 kHz. Tests performed by 10 Applicant have shown that excellent cleaning of the fabric tape is achieved using ultrasound at a frequency between 30kHz and 32kHz. In one aspect, the two rollers or cylinders 113 at least partially submerged by the liquid washing machines are arranged so that a first ultrasonic generator 115 is installed between the two immersed rollers or cylinders 113, and a second generator 15 ultrasonic 114 is installed so that the two immersed rollers or cylinders 113 are on one side same side as the second ultrasonic generator 114. As shown in the figure 1 attached, the two ultrasonic generators 114, 115, are oriented so as to emit ultrasound in the same direction and thus impact two opposite faces of the fabric ribbon F which is immersed in the washing liquid. 20 The configuration with the two ultrasonic generators 114, 115, directed against each other towards opposite faces of the same portion of tissue F is not preferred because the two generators could create destructive ultrasound interference, which would reduce the effectiveness of washing the fabric. In one aspect, the ultrasonic generators 114, 115, are individually activatable and 25 deactivatable to allow the user to configure the washing system 100 a to your liking, thus being able to perform a traditional wash with just the nozzles 120 sprayers, both a wash and benefits from the synergistic action of the 120 nozzles that They spray washing liquid at relatively low pressure and ultrasonic generators 114, 115 which perform a deep cleaning of the fabric using washing liquid 30 at the lowest temperature.

Claims

1. Washing system (100) for washing fabric webs in continuous, open or tubular mode, said system (100) comprising: i) at least one washing unit (110) inside which are housed a washing tank (111) intended to contain a washing liquid and a rinsing tank (112) intended to contain a rinsing liquid, ii) a plurality of rollers or cylinders (113) arranged inside said washing unit (110) and configured to rotate around their own axis, said rollers or cylinders defining a washing path which extends from an inlet (116) to an outlet (117) of the washing unit (110), wherein at least some of said rollers or cylinders are motorised, iii) a plurality of nozzles (120), or alternatively slots, suitable for delivering jets of washing liquid towards opposite faces of a fabric web (F) in transit along the washing path, iv) a heating device (118) for said washing liquid,configured to heat the washing liquid in the washing tank (111); characterised in that said heating device (118) is adjustable to heat the washing liquid to an operating temperature set by a user; said washing unit comprises at least one ultrasonic generator (114, 115) arranged in the washing tank (110) so as to be at least partially submerged by the washing liquid and so as to generate ultrasonic sound waves directed against at least one face of said fabric web (F) passing immersed in said washing liquid in the washing tank (111)., 2. Washing system according to the preceding claim, wherein said washing unit (110) comprises two ultrasonic generators (114, 115) arranged in the washing tank (111) so as to be at least partially submerged by the washing liquid and so as to generate ultrasonic sound waves directed in a concordant direction against opposite faces of said fabric ribbon (F) in transit immersed in said washing liquid in the washing tank (111).

3. Washing system according to the preceding claim, comprising two SIB - 9 BI3259M-te rollers or cylinders of said plurality of rollers or cylinders (113) positioned in said washing tank (111) so as to be submerged by the washing liquid when the washing tank (111) is filled, wherein a first ultrasonic generator (115) of said two ultrasonic generators is installed between said two rollers or cylinders (113) and a second ultrasonic generator (114) of said two ultrasonic generators is installed so that said two rollers or cylinders (113) are on the same side with respect to the second ultrasonic generator (114).

4. Washing system according to one of the preceding claims, wherein said nozzles or slots (120) are directed so as to spray said washing liquid before said passing fabric web (F) is immersed in the washing liquid of said washing tank (111).

5. A method of washing fabric ribbons in a continuous, open or tubular manner, comprising: providing and installing a system (100) according to one of claims 1 to 4; filling said washing tank (111) with washing liquid so as to at least partially submerge said at least one ultrasonic generator (114, 115) of the system (100); delivering jets of washing liquid or rinsing liquid towards opposite faces of a fabric ribbon (F) in transit along the washing path of said system (100); generating ultrasonic sound waves directed against at least one face of said fabric ribbon (F) in transit immersed in the washing liquid in the washing tank (111).

6. Method according to claim 5, comprising: providing and installing two ultrasonic generators (114, 115) in the washing tank (111) so as to be at least partially submerged by the washing liquid and so as to generate ultrasonic sound waves directed in a concordant direction against opposite faces of said fabric web (F) in transit immersed in said washing liquid in the washing tank (111).

7. A method according to one of claims 5 to 6, comprising the step of generating ultrasound, by means of said at least one ultrasound generator (114, 115), at a frequency of not less than 20 kHz, preferably between 30 kHz and 32 kHz.

8. A method according to one of claims 5 to 7, comprising the step of heating the washing liquid in the washing tank (111) to an operating temperature not exceeding 70°C.