ELECTRONIC CONTROL SYSTEM OF A FABRIC DYEING MACHINE

The present invention refers to an electronic control system of a fabric dyeing machine, wherein it is possible to map the fabric to be dyed.

The "electronic" mapping of the fabric thus allows the traditional control methods of the dyeing process of fabrics to be revolutioned. The use of radiofrequency for monitoring the dyeing process is applicable to more than one dyeing method.

"Rope dyeing" indicates the dyeing process wherein the fabric takes on a particular cord-shaped structure during the processing operations. Nowadays, various types of dyeing machines are available on the market, which are differentiated by their constructive and operating characteristics according to the type of fabric to process, the type of colouring agent used (which may require operating under particular temperature and/or pressure conditions) , and the possibility of operating continuously or discontinuousIy .

Essentially, the fabric handling system inside the dyeing machine is comprised of one or more stave or smooth drive rolls, of one or more nozzles fed with air by special fans or a flow of water (systems named "JET" or "FLOW" or with tapered section nozzles) from special

pumps and from one or more fabric storage tanks . The current machines present a series of limitations that are overcome with the solution object of this patent . Let's consider, for example, the traditional machines, where the fabric handling control inside the dyeing machine is normally carried out for each single fabric rope being provided, through the use of a permanent magnet and a corresponding detection coil . The information obtained is limited to detecting the time elapsing between the subsequent passages of the magnet at the control point. This detection allows for determining the real rope fabric circulation speed while highlighting possible fabric slipping problems on the drive rolls and determining the position of preset points (i.e. seams) . The update of information on the real speed of the rope and the possible correction interventions occur at intervals, whose duration can be significant, determined only by the subsequent passages of the permanent magnet.

Should more magnets be used there would not be any possibility of unequivocally identifying the single magnet during the dyeing process . The information that may be obtained with the magnet-coil system is in fact of on-off type and even with the use of complex software based on empiric data for the management of

the fabric handling inside the dyeing machine, the control system is not capable of recognising with absolute certainty which part of the fabric is going through the various control points . A further development in the traditional technology was introduced with the Italian patent application N° MI93A1474 wherein information on the passage of the permanent magnet is used for the balancing of the fabric in the storage tanks and for the control of variables linked to the dyeing process, such as the temperature increase/decrease gradients or the product inlet times. Thanks to the processing uniformity allowed for by such a system, it is in fact possible to determine the times of numerous phases in the dyeing process according to the number of fabric runs (fabric run = time needed by the fabric to go through 2 or more machine storages) replacing the times empirically determined in order to ensure the uniformity of the dyeing result . The Applicant noted that the solutions set forth above present some limitations.

Dyeing pieces with various chemico-physical characteristics (weight, height, type of fabric, elasticity...) in a single dyeing requires, during the loading phase, a particular arrangement of the fabric, (e.g. succession between light and heavy fabrics) if

one tries to ensure the homogeneity of the fabric distribution inside the tanks.

This is essential as the system is exclusively based on the detection of the time of passage of the magnet from one tank to the next and therefore it is not capable of determining which part of the fabric it is handling. The preset speed causes the accumulation or lack of fabric in the tanks according to the physical characteristics of the latter. The technical problems related to the management of more magnets limit, in practice, their use to a number substantially lower than the number of existing storages . The information that may be obtained by such a configuration determines a control time of the passage of the fabric in the storage tanks. The higher the number of storages and the greater their loading capacity, the longer such time will be. The lack of prompt information may force the control system to react to possible lacks of balance more slowly than necessary, both for the control of the parameters

(dosages, temperatures...) and the balancing of the storages. In fact, it must wait for at least one full cycle to be concluded, before it can control again the position and thus the speed of the fabric. Therefore, a buffer should be ensured so as to compensate possible fabric accumulations in one or more storage tanks.

This leads to the impossibility of fully exploiting the loading capacity of each single tank, for example in a variable range between 10% and 20%.

From the system reliability point of view, in case two or more magnets are used, the seriousness of the detection loss of even a single passage of the magnet is highlighted. Moreover, this phenomenon is not uncommon in the practice which requires complex and non-secure operations to reconstruct the actual arrangement of the fabric in the tanks. Furthermore, the useful interval for the detection of the signal between the permanent magnet and the coil is limited. The placement of the coils must be carried out in particular points to actually reduce the distance between them and the magnet.

The system may not be used for the synchronisation of the motorised fabric storages with the fabric handling system (i.e. drive rolls) since it is not possible to ensure the correct arrangement of the magnet or the magnet-coil distance within the limits of accurate detection. The Applicant found that through the use of the RFID technology all the problems set forth above are solved. RFID devices are devices capable of storing and transmitting information, when interrogated in a timely manner.

A system for the detection of transponders allows for

constantly monitoring their position during the entire dyeing process. By means of radiofrequency it is possible to update the information contained in the transponders with data related to the technological process that the fabric underwent .

The identification system is based on 4 main components: the transponder, also called "tag", the reader, the antenna and the control software. The system also comprises a microprocessor unit which preferably contains the software, with which such RFID readers capable of reading and/or modifying the information contained in the tags are associated and with which such antennas that interface with such devices are associated. In particular, the antennas may be of different shapes, and adapted according to the type of field that one wants to generate. This makes them easy to install and capable of adapting to specific needs. The transponder or tag may be of passive or active type. The choice of the type of tag to be used simply depends on the type of information that one intends to manage. During the connection with the reading device, the tag exchanges the information that it contains while also allowing for, if needed, its update. The detected information is communicated to the control system (processor or PLC) of the machine in order to be timely

managed .

The number of tags applicable to the fabric strictly depends on the type and on the level of control that one wants to carry out. This system allows for the control of the position of every single tag.

An aspect of the present invention concerns an electronic control system of a fabric dyeing machine according to claim 1, to which it is referred for conciseness . The characteristics and the advantages of the system according to the present invention will be clearer and more obvious from the following description of two exemplary and non-limiting embodiments, wherein the accompanying figures represent: • figures from Ia to Ie a rope dyeing machine with three tubes;

• figures 2a and 2b a rope dyeing machine with motorised rotating storage tank. Referring to figure 1, the machine comprises one reservoir 1, three storage tanks 2, 3, 4, three drive rolls Ml, M2, M3 , and three nozzles Fl, F2 , F3 which constitute an example of a handling device of the fabric in the machine. According to a characteristic of the present invention, the antennas may be positioned both upstream from the handling system indicated in positions Al, A2 , A3 and downstream in positions Bl, B2

e B3. However, nothing prevents the choice of alternative positions or the addition of further control points. The tags T are preferably fixed to the fabric and move together with it. The passage of the tag T near the antennas allows for the exchange of information needed by the machine control system. The inventive concept is equally applicable to other types of machines for rope dyeing.

In figure 2, a rope dyeing machine with motorised rotating storage tank D is represented. The machine is comprised of one reservoir 1, one drive roll 2 and one nozzle 3 which constitute an example of a handling device of the fabric in the machine .

According to an aspect of the present invention, the antennas are positioned both at the rear of the fabric handling system (position Al) and directly on the storage tank (positions Bl and B2) . The tags T are detected near the installed antennas. Preferably, the antennas placed in positions Bl and B2 allow for the actual monitoring of the arrangement of the fabric in the tank. Also for the type of machine depicted in figure 2, the number and position of the antennas depends on the type and on the level of monitoring considered necessary. For example, the antennas may be distributed along the entire run of the fabric inside the machine . The control system through radiofrequency

technology thus designed is open to numerous modifications and changes, all within the invention. Furthermore, all the details are replaceable by technically equivalent elements. In practice, depending on availability and technical needs, all the materials used, as well as the dimensions, may be of any kind. Taking into consideration, for example, "single rope dyeing" , the possibility of controlling with absolute precision the passage of every tag in preset positions of the machine allows for resolving the root of the problem of setting the quantity of fabric found in the single storage tanks by carrying out a prompt and accurate correction of the fabric pulling speed through the members in charge of handling, whether they are drive rolls and/or tapered section nozzles and/or "JET" and/or "OVER FLOW" and/or "AIR" . This allows for optimising the processing of various fabrics during the same dyeing cycle. The machine is capable of identifying every single piece of fabric where an RFID tag has been applied and of adapting the pulling speed based on specific needs. In this case, the loading sequence turns out to be independent from the type of fabric loaded. The tags will be the ones driving the pulling speed to ensure its homogeneous distribution in the tanks.

With the use of the new system, an improvement in the

exploitation of the loading capacity of every single tank is obtained. By knowing the arrangement of the fabric in the tanks the need to have the buffer necessary to compensate possible abnormal accumulations of fabric will be avoided.

Thanks to the RFID technology, it is further possible to adapt the dyeing process in each single phase, for example by measuring the dosage of chemical auxiliaries. The dosage is no longer linked to the time intervals detected by the passage of the magnet in preset points, but may be applied directly on specific parts of the fabric .

The use of the RFID technology offers several advantages also in "multiple rope dyeing" . Besides what has been discussed in the case of a single rope, the following considerations are valid:

• it is possible to write the information on the tags directly during the dyeing process therefore obtaining the full traceability of the applied process; • the unloading operations are facilitated, assisting in the identification of the exact point in which the piece's seams were made. In the case of more pieces, the system may automatically stop the unloading procedure at the change of piece, separating if needed their storage.

• by being capable of detecting the passage of the

single tag even in points in which the position of the rope is not predefined (for example when the fabric is accumulated in the tanks) it is possible to both control the handling of the fabric inside the tank and, in the case of motorised storages, provide for the synchronisation of the latter with the handling members in charge.

Every RFID tag is unequivocally identifiable in the prearranged control points during the dyeing process, varying from machine to machine according to the variables one intends to control. According to the control points fixed in the machine one is capable of knowing the exact arrangement of the fabric inside the machine itself. The information contained in the tag applied to the fabric is exchanged with the reader with the aim of informing the machine control system in order to accomplish the various control functions related to the dyeing process. The RFID control method is applicable to all situations in which it is useful to inform the management system of the dyeing machine with the information contained in one or more tags . This information may be used for both the control of the machine's operation and the dyeing process. Mapping allows for adapting, on the basis of various specific needs, various parameters of the process such as, for example, the fabric pulling speed, bath rotation speed,

temperature change speed, solid (salt, sulphate) introduction speed, alkali/acid introduction speed.