Patent Description:
For the sake of greater clarity and simplicity of explanation, the dyeing machine according to the present invention will be described by way of non-limiting example, with reference only to dyeing of hank yarns using indigo dye. It is however specified that, in addition to the foregoing, the dyeing machine according to the present invention is also suitable for dyeing of hanks of any fibre using the appropriate different classes of dyes, as well as, it will be appreciated subject to use of a suitable inner rotary material-carrier frame, for dyeing of ready-made garments such as socks, sweaters, jeans and the like, whether made of knitwear or fabric.

For millennia, natural indigo, extracted by grinding numerous plants of the indigo genus and various others, common in India and Java, was the blue colour par excellence for wool, linen, silk and cotton. In <NUM>, the German chemical company BASF determined the formula of indigo, and, a few years later, it put on the market the new synthetic indigo, with a substantially lower cost, which soon replaced the natural type. However, after the discovery in <NUM> by the German chemical company CASSELLA of the blue dye "Hydron", which is easier to apply, has better fastness and a significantly lower cost, within a few years indigo fell completely into disuse.

Nevertheless, the particular characteristic of indigo, i.e. the fact that after repeated washings its blue tends to lighten until it becomes an increasingly brighter light blue, in contrast with the new "Hydron" blue which on the other hand tends to become opaque, meant that, about <NUM> years later, indigo returned to favour with the initial successes of jeans, the trousers which, from a humble working garment, became synonymous with leisure time, to the extent that they rose to the ranks of high fashion and became a clothing classic worldwide.

Nowadays, as was the case in the past, dyeing of yarns using indigo, which is indissolubly associated with jeans, as a result of changed social requirements, the continual development of fashion, etc., is once again required in order to complete, modernise and make available the production of new articles of clothing. This is because indigo is the only dye with the particular characteristic that, over a period of time, after various washings, it makes the colour tone of garments to be produced, as is the case for classic jeans, increasingly lighter, but also very bright, and therefore gives them a very pleasing appearance.

One of the characteristics of indigo dye, which makes it unique, is the particular dyeing method required for its application to cotton yarn. This dyeing method has remained virtually unchanged from the times of use of the vegetable dye up to the present, over a hundred years since it was synthesised. As a result of its relatively small molecule and low affinity with cellulose fibre, in order to be applied indigo dye must not only be reduced in (leuco compound) alkaline solution, but also needs to be subjected to a plurality of impregnations, alternating with wringing and subsequent oxidations in air. In practice, a medium or dark shade is obtained only by subjecting the yarn to a first dyeing operation (constituted in sequence by the phases of impregnation, squeezing and oxidation), followed immediately by a plurality of overdyeing operations, which are all the more numerous the darker the shades and the greater the colour fastness required.

However, whereas this working methodology has easily been applied to continuous dyeing of denim fabric in order to produce jeans, since it is carried out on lines constituted by a sequence of dyeing tanks, each provided with devices for squeezing and oxidation, the same working methodology is not as easy, or rather it is very difficult to apply, using the traditional discontinuous dyeing machines of the type known as "batch", for various garments made from hank yarn. Undoubtedly, the very lengthy period of complete lack of use of indigo dye except for jeans, together with the lack of interest in new particular uses, has not stimulated research and experimentation in this respect.

The product which lends itself best to the methods for discontinuous (batch) dyeing with indigo, out of a vast range of cotton yarns and other fibres, is that of the hank type. Dyeing of yarns in hank form is perhaps the oldest system (albeit with continuous technological modernisation) which, for various reasons and technical requirements, is still extensively in use utilising various classes of dyes (excluding indigo).

In the past, in the case of indigo, the hanks were dyed in wooden tanks, immerse suspended on special rods shaped in the form of an inverted omega, such as to keep these hanks completely immersed in the dye bath, in order to prevent oxidation of the dye. The position of the hanks was changed manually, on these rods, which in turn were moved from one side of the tank to the other. When the dyeing was completed, the hanks were wrung out and exposed to the air for oxidation. These operations had to be repeated several times depending on the colour shade required.

Dyeing of hank yarns is still in use, wherein it is a product where the yarn is wound freely, softly, regularly and voluminously, so as to keep all of the characteristics thereof unaltered. These qualities are greatly valued in the knitwear sector, especially for fine and delicate fibres. Furthermore, hanks are a product wherein the yarn is wound in the form of a loop, and thus in the only condition which, by means of a particular machine, allows the cotton hanks to be tensioned during the mercerisation treatment, which is a particularly important treatment for the knitwear and shirt production sectors.

Mercerisation, as it is known universally in honour of its inventor, John Mercer, is a process by means of which, through the action of concentrated caustic soda and at a low temperature, the cotton yarn is subjected to considerable shrinkage which, if prevented, gives rise to a silky sheen of the fibre. In practice, the more strongly the shortening of the yarn is generated by means of the caustic soda, and the more efficiently this shortening is prevented, the better the sheen of the yarn which is obtained.

As well as providing the yarn with the particular sheen, the mercerisation treatment also gives it greater mechanical strength, with improvement of the resilient "coating", in addition to the important property of being dyed more intensely than the same yarn when not mercerised, thus resulting in a significant saving of dye.

For all of these particular characteristics, mercerised yarn is of great importance for the sectors of knitwear and shirt production which, if they have the possibility of being able to dye also with indigo, have the opportunity to expand considerably the availability of new products, which are in great demand in the fashion industry, resulting in revival of the corresponding markets in times of crisis. If yarn dyed with indigo is well fixed, and above all does not shed dust, even when it is not mercerised it is of particular interest for the potential production of a vast range of new types of smooth and worked fabrics and knitted work, as well as, in addition to conventional plushes, to make available also other sportswear articles and knitted jeans, which are in demand because they are far more convenient, easier to put on, and more comfortable than the traditional type.

The machines available worldwide at present for dyeing of hanks consist almost entirely of the "cabinet" type, so-called because of the vertical parallelepiped form of these machines, where the hanks, suspended on a series of rods, with adjacent blocks and on one or two levels, are completely immersed in the dye bath, and kept in two-way circulation, i.e., down/up and up/down, by means of a pump. These machines operate at full volume with a mean ratio of approximately <NUM> to <NUM> between the weight of the yarn and the volume of the dye bath. These are machines which are in no way suitable for dyeing with indigo because of the subjective structural difficulties and need for many manual operations, with consequent very high costs, and above all quality results which are not optimal.

In fact, in order to be able to dye with indigo using the traditional process involving successive phases of impregnation, squeezing and oxidation, after the first dyeing operation it would be necessary to empty the cabinet, recuperating the dye bath, extract the hanks, spin them, and oxidise the dye in air. The hanks would then have to be reintroduced into the cabinet in order to repeat all the phases again, on further occasions, until the desired colour shade was obtained. This shows clearly that, in the present cabinet dyeing machines, in practice it is impossible to dye hanks with indigo, except by carrying out a single cycle, to obtain very light shades, with many manual operations, and with quality results which are not excellent.

On this basis, even though it may seem absurd, it must be admitted that, compared with the modern system of dyeing in cabinet machines, in the case of indigo the old manual system would be simpler and less intricate, with the tank totally immersed in the hanks, obviously with all the operations carried out automatically. However, this is a system which it would be unthinkable to create nowadays.

Even though they were not specifically designed for dyeing with indigo, around <NUM>/<NUM> two hank dyeing machines were developed which modernised the old tank system, i.e. with the dye bath stationary and with manual movement and translation of the rods with the hanks. Although the dye bath was always stationary, these two dyeing machines made it possible to place the hanks on rods disposed in the form of spokes on a rotary hank-carrier. One of these two machines was produced towards the end of the <NUM>th century by the German textile engineering company ZITTAUER. The other machine is illustrated on page <NUM> of the Italian monthly review "LANIERA" of October <NUM>.

A third hank dyeing machine, similar to the above two machines from a design point of view, is illustrated in document <CIT>. In this dyeing machine, the hank carrier is however divided into two sections. As well as being altogether unsuitable for dyeing with indigo, like the two above dyeing machines the dyeing machine which is illustrated in document <CIT> has many design and functional problems, i.e.:.

Even if the above-described problems were overcome from an operative point of view, the dyeing machine illustrated in document <CIT> would still have an insurmountable problem in common with the two other aforementioned dyeing machines, which make it altogether unsuitable for dyeing with indigo. In fact, during the dyeing, some of the spokes with the hanks (in the two aforementioned dyeing machines) and one of the two hank-carrier sectors (in the dyeing machine illustrated in document <CIT>) still remain alternately in contact with the air, and therefore in a condition of detrimental oxidation of the bath for dyeing the respective hanks.

Further dyeing machines are illustrated in documents <CIT> and <CIT>. However, these dyeing machines are altogether unsuitable for dyeing with indigo dye either of hank yarns or ready-made garments. In fact, during the dyeing, in these machines most of the textile material to be dyed always remains alternately in contact with the air, and therefore in a condition of detrimental oxidation of the respective impregnation bath. It should be noted that, because of its design and operative characteristics and the particular system of positioning of the hanks, the dyeing machine illustrated in document <CIT> cannot be used for industrial production. In addition, the dyeing machine illustrated in document <CIT> does not have either support devices for hanks stretched between two arms, or support devices for hanks suspended on standard rods. Without these support devices, the yarn of the hanks which are placed in the cells of the rotary basket, which is free to move and roll, would become matted and tangled, thus making the subsequent disentangling operation, and therefore use of the yarn itself, impossible. In fact, the dyeing machine which is illustrated in document <CIT> appears to be a conventional rotary dyeing machine for ready-made garments, using a principle which for over <NUM> years has also been applied universally to both industrial and domestic washing machines.

The object of the present invention is thus to provide a machine for environmentally sustainable dyeing with indigo and other dyes, of hank yarns and/or ready-made garments, which can eliminate the aforementioned disadvantages of the prior art in a manner which is extremely simple, economical, ergonomic, ecological and particularly functional.

In detail, an object of the present invention is to provide a machine for dyeing with indigo of hank yarns and/or ready-made garments which permits execution of the entire dyeing cycle sequentially, directly in its interior and in an inert environment, such as to provide a series of not only economic, but also quality advantages in terms of fastness, fixing of the dye, and brightness of the dyeing.

Another object of the present invention is to provide a machine for dyeing with indigo of hank yarns and/or ready-made garments which makes it possible to reduce the number of dyeing phases to a single one.

Another object of the present invention is to provide a machine for dyeing with indigo of hank yarns and/or ready-made garments which can operate with the minimum quantity of dye bath possible, such as to reduce substantially the consumption of energy, water and chemical products (caustic soda and sodium hydrosulphite), and consequently reduce the production costs.

Another object of the present invention is to provide a machine for dyeing of hank yarns and/or ready-made garments which, under nitrogen with indigo and other reduction dyes, or in contact with the air with other classes of dyes, can operate with a very low ratio between the weight of the yarn and the volume of the dye bath, with the bath closed, with or without internal recirculation, and with or without upper sprinklers, with the material-carrier frame with one or two stages rotating slowly in both directions.

Another object of the present invention is to provide a machine for dyeing with indigo of hank yarns and/or ready-made garments which makes it possible to carry out exclusive dyeing cycles with high-concentration dye baths, and also at a low and/or high temperature.

Another object of the present invention is to provide a machine for dyeing with indigo of hank yarns and/or ready-made garments which makes it possible to recuperate used dye baths containing indigo, such that, after titration and topping up of the various components, these dye baths can be reused.

Another object of the present invention is to provide a machine for dyeing with indigo of hank yarns and/or ready-made garments which uses the minimum possible volume of dye bath, so as to render economical the possibility of applying a system for cooling of the dye bath itself to approximately <NUM> in order to take advantage of the maximum affinity with the fibre, as well as the possibility of applying an ultrasound generator, in order to increase the colour yield further.

A further object of the present invention is to provide a machine for dyeing with indigo of hank yarns which is particularly suitable for mercerised yarns for knitwear, shirt production and other particular uses.

Yet another, very important object of the present invention is to provide a machine for dyeing with indigo and other dyes of hank yarns which, using the same hank-carrier rods as the dyeing cabinets according to the prior art, and with the same vertical loading system, creates advantageous operative interchangeability with these.

These objects according to the present invention are achieved by providing a machine for dyeing with indigo and other dyes of hank yarns and/or ready-made garments, as described in claim <NUM>.

Further characteristics of the invention are indicated by the dependent claims, which are an integral part of the present description.

The dyeing machine according to the present invention extends horizontally, and is designed to carry out dyeing of hanks and/or ready-made garments under nitrogen or in contact with the air (at atmospheric pressure or under static pressure), with partial filling and a reduced volume of the dye bath, which contains in its interior one or more material-carrier frames (for hanks on standard rods, which are common to all the dyeing cabinets according to the prior art) rotating on a single axis with a variable speed and in both directions. This dyeing machine can thus execute in its interior the entire dyeing operative cycle both with indigo, and with other classes of dyes.

The dyeing machine according to the present invention does not have any of the aforementioned disadvantages of the dyeing machines of the known type, since it operates in an inert environment (preferably under nitrogen), in a rational, ergonomic, and environmentally sustainable manner. The fact that it operates in the particular condition of an inert environment (preferably under nitrogen), with a very low ratio between the weight of the yarn and the volume of the dye bath, equal to approximately <NUM> to <NUM>, makes it possible to execute completely in its interior not only dyeing using the traditional operative method, but also dyeing with an innovative process which is monophase and/or repeatable, without intermediate oxidation, as well as individual special operative cycles with high-concentration dye baths at a low and/or high temperature, which cannot be carried out on traditional dyeing machines. All of this is performed very rapidly and in an environmentally sustainable manner.

The dyeing machine according to the present invention also has the practical advantage of using the same hank-carrier rods as those which are commonly used by all the cabinet dyeing machines according to the prior art, with which it can therefore operate in perfect synergy.

The characteristics and advantages of a machine for dyeing of hank yarns and/or ready-made garments according to the present invention will become more apparent from the following description, provided by way of non-limiting example, with reference to the appended schematic drawings in which:.

It is specified that the following description and the appended figures do not illustrate, since they are well known to persons skilled in the art, numerous components, accessories and instruments with which all dyeing machines are normally equipped, such as, for example, dye bath level regulators, thermal regulation units, preparation containers, units for recovery of the dye baths and supply of auxiliary products, automatic metering systems, command and control instruments, etc. It is also specified that the appended figures illustrate hydraulic circuits, provided with respective pumps and valves, which will not be described in detail hereinafter, since these are also well known to persons skilled in the art.

The figures show two possible embodiments of the machine for dyeing of hank yarns and/or ready-made garments according to the present invention. The dyeing machine is indicated as a whole by the reference number <NUM>, and is designed to carry out the dyeing of hank yarns and/or ready-made garments both with indigo and other reduction dyes, in an inert environment and preferably under nitrogen, as well as with other classes of dyes, in air.

The dyeing machine <NUM> comprises at least one dyeing apparatus <NUM> provided with:.

The dyeing machine <NUM> also comprises at least one support frame <NUM>, which is mounted such as to rotate within the dye compartment <NUM> and is designed to rotate, by means of at least one rotation pin <NUM>, around a central axis of rotation A which is substantially horizontal and passes via the rotation pin <NUM>. The rotation of the support frame <NUM> can be controlled, in a known manner, by one or more electric motors <NUM> or by other movement means suitable for the purpose.

The dyeing machine <NUM> also comprises at least one tank <NUM>, <NUM> (<FIG>), or <NUM>, <NUM> (<FIG>), containing at least one dye bath B and at least one hydraulic circuit <NUM>, which is connected hydraulically to each tank <NUM>, <NUM> or <NUM>, <NUM>, and to the dyeing apparatus <NUM> in order to supply the dye bath B from each tank <NUM>, <NUM> or <NUM>, <NUM> to the dye compartment (<NUM>) and vice versa. The dyeing machine <NUM> also comprises a plurality of support means <NUM>, <NUM>, <NUM> for the hank yarns and/or the ready-made garments, which means are mounted on the support frame <NUM> and are accessible via the hatch <NUM>.

Both the casing <NUM> and the support frame <NUM> preferably have a circular form in vertical transverse cross-section, i.e. a cross-sectional obtained along a plane orthogonal to the central axis of rotation A of the support frame <NUM>, such that the casing <NUM> has a cylindrical frontal wall and the dye compartment <NUM> thus has a cylindrical form. Each hatch <NUM> is provided on the cylindrical frontal wall of the casing <NUM> and the support means <NUM>, <NUM>, <NUM> are disposed on the support frame <NUM> according to a configuration which is preferably circumferential relative to the central axis of rotation A, and the means are placed in the vicinity of the inner surface of the cylindrical frontal wall of the casing <NUM>, as shown for example in <FIG>, <FIG>, <FIG> and <FIG>.

Each support frame <NUM> is delimited by a pair of preferably circular lateral walls <NUM>, <NUM> which are substantially flat, opposite one another, and disposed orthogonally relative to the central axis of rotation A. For example, <FIG> shows a dyeing apparatus <NUM> which is provided with a single support frame <NUM> (single-stage configuration). On the other hand, <FIG> shows a dyeing apparatus <NUM> which is provided with two distinct support frames <NUM>, which are adjacent to one another in the direction of the central axis of rotation A (configuration with two stages). However, it is not excluded for the dyeing apparatus <NUM> to be provided with three or more distinct support frames <NUM>, always disposed adjacent to one another in the direction of the central axis of rotation A.

Preferably, each hatch <NUM> has a width, measured along the central axis of rotation A, which is substantially equal to the distance L between the two lateral walls <NUM>, <NUM> of each support frame <NUM>. In other words, each hatch <NUM> is "all front", to the advantage of the loading and unloading operations of the hank yarns and or the ready-made garments into and from the dyeing apparatus <NUM>.

In the embodiments in <FIG>, <FIG>, <FIG> and <FIG>, the dyeing machine <NUM> is designed for dyeing of hank yarns. Each of the support means <NUM> is thus constituted by a rack which supports a plurality of hank-carrier rods <NUM> for dyeing of the hank yarns. In the variants in <FIG> on the other hand, the dyeing machine <NUM> is designed for dyeing of ready-made garments. Each of the support means <NUM>, <NUM> is thus constituted by a perforated compartment or container provided with at least one opening <NUM>. Each perforated compartment or container <NUM>, <NUM> is designed to contain the ready-made garments and to dye them by means of passage of the dye bath B through the holes with which this perforated compartment or container <NUM>, <NUM> is provided.

Solely by way of example, in the embodiments of the dyeing machine <NUM> in <FIG>, <FIG>, <FIG> and <FIG>, designed for dyeing of hank yarns, each support frame <NUM> can have one or two stages. Each support frame <NUM> can thus preferably be designed to contain six racks <NUM>, disposed circumferentially in a "hexagon" configuration if seen in vertical transverse cross-section (as shown for example in <FIG> and <FIG>) and each bearing three or four rows of hank-carrier rods <NUM>.

According to the invention, the hydraulic circuit <NUM> comprises one or more nitrogen and air supply circuits <NUM>, which are connected hydraulically to each tank <NUM>, <NUM> and to the dye compartment <NUM> with a cylindrical form, such as to be able to supply them with nitrogen N. Unlike the dyeing machines according to the prior art previously described, this technical characteristic makes it possible to dye, with indigo and other reduction dyes in an inert environment, hank yarns and/or ready-made garments inside the dye compartment <NUM>.

The two different embodiments of the dyeing machine <NUM>, one shown in <FIG> and the other in <FIG>, are in fact distinguished by the dyeing method and the type of dye bath B used. The embodiment of the dyeing machine <NUM> in <FIG> is designed to carry out dyeing with indigo and other reduction dyes, in an inert environment and under nitrogen. The dyeing machine <NUM> thus comprises a first hermetically sealed tank <NUM> containing an indigo-based dye bath B and a necessary quantity of nitrogen N, and a second hermetically sealed tank <NUM>, which is connected hydraulically to the first hermetically sealed tank <NUM>, and acts as an auxiliary tank for the indigo-based dye bath B and for the necessary quantity of nitrogen N. In this embodiment of the dyeing machine <NUM>, each nitrogen and air supply circuit <NUM> is connected hydraulically both to the first hermetically sealed tank <NUM> and to the second hermetically sealed tank <NUM>. Also, in this embodiment of the dyeing machine <NUM>, the dye compartment <NUM> with a cylindrical form can be provided in its interior with at least one chamber <NUM> which serves the purpose of a reduction plenum chamber for the volume of nitrogen N contained in this dye compartment <NUM> with a cylindrical form.

On the other hand, the embodiment of the dyeing machine <NUM> in <FIG> is designed to carry out dyeing in air with dyes different from indigo. The dyeing machine <NUM> thus comprises a first tank <NUM> which operates in air, containing a bath B for dye different from indigo, and a second tank <NUM> which operates in air, and is connected hydraulically to the first tank <NUM> which operates in air and acts as an auxiliary tank for this bath B for dye different from indigo. Consequently, in this embodiment of the dyeing machine <NUM>, the nitrogen and air supply circuits <NUM> are not used.

Independently of the embodiment, the dyeing machine <NUM> can comprise at least one recirculation circuit <NUM> for the dye bath B contained in the dye compartment <NUM> with a cylindrical form. The dyeing machine <NUM> can also comprise one or more cascade sprinkler devices <NUM>, which are connected hydraulically to the dyeing apparatus <NUM> by means of the hydraulic circuit <NUM>, and are designed to sprinkle directly the dye bath B in the dye compartment <NUM> with a cylindrical form. The dyeing apparatus <NUM> and/or at least one of the tanks <NUM>, <NUM> can also be provided with means <NUM> for thermal regulation of the dye bath B. These means <NUM> for thermal regulation can be constituted by one or more heating and/or cooling pipe coils of the dye bath B. The dyeing apparatus <NUM> can finally be provided with one or more ultrasound generators <NUM> in order to increase the colour yield further.

The dyeing machine <NUM> is thus designed to immerse the hanks or ready-made garments in the dye bath B, which occupies the lower part of the dye compartment <NUM>. In the absence of the dye bath B, the dyeing machine <NUM> can also carry out the spinning directly, and, subject to discharge of the nitrogen N and intake of air, it can carry out oxidation of the hanks or ready-made garments by means of rotation of the support frame <NUM> around its own central axis of rotation A. Because of its particular design form, the dyeing machine <NUM> in fact makes it possible to dye with a very low ratio between the weight of the yarn and the volume of the dye bath B, equal to approximately <NUM> to <NUM>, compared with a value of <NUM> to <NUM> of the dyeing cabinets according to the prior art, as well as to spin and oxidise the dyed yarn and/or the ready-made garments directly in its own interior.

The dyeing machine <NUM> can also dye in an inert environment (this is a particular and advantageous ecological technology described in documents <CIT> and <CIT> in the name of the same applicant, as well as in document <CIT>), using hank-carrier rods <NUM> with the same measurements as, and/or coming from, conventional cabinet dyeing machines. This interchangeability of the hank-carrier rods <NUM> is very important and extremely convenient, since it allows the dyeing machine <NUM> to be used for the purpose of increasing productivity significantly, only for the true dyeing phase of the operative cycle, whereas on the other hand the remaining initial operations (soaking up, steeping, etc.) and final operations (washing, soaping, softening, etc.) can also be carried out in the conventional cabinet dyeing machines.

The particular preferred structural form of the dyeing machine <NUM> and of its rotary support frame <NUM>, i.e., provided with six independent support means <NUM> with a narrow thickness, and with only three or four rows of hank-carrier rods <NUM> has been designed in order to:.

In addition to the above particular characteristics, the fact of operating in an inert environment, preferably under nitrogen, makes it possible to modernise the known operative cycle for dyeing with indigo, constituted substantially by three operative phases which are repeated several times (impregnation of the yarn with the leuco compound, elimination of the excess dye bath contained therein, and oxidation of the dyed yarn), with the addition of a fourth operative phase, i.e., that of diffusion/fixing of the leuco compound in an inert environment. In addition, by means of operation under nitrogen, i.e., in an inert environment, the dye bath B which impregnates the hanks held by the support means <NUM>, which emerge cyclically from this dye bath B, not only does not oxidise, but, since it remains in the leuco compound state, continues its action of diffusion and fixing in the fibre.

Operating under nitrogen not only makes it possible to shorten the operative times significantly, but also to be able to carry out innovative single-phase dyeing cycles, with dye baths at a high concentration and a high temperature, as well as to reduce by <NUM>% to <NUM>% the consumption of caustic soda and sodium hydrosulphite. Under nitrogen, the chemical reduction of the indigo is total and perfect, and the leuco compound is broken up into particles with a nanometric dimension. Compared with the traditional systems, this characteristic increases the dyeing capacity of the indigo, improves the penetration thereof, and intensifies the fixing thereof on the fibre, with a substantial saving of washing water and with excellent results in terms of fastness, intensity and brightness, which are essential characteristics for yarn to be used in shirt production and knitwear.

Further technical improvements are provided by the possibility, allowed by the very low volume of dye bath B, of applying thermal regulation means <NUM> economically. In particular, these thermal regulation means <NUM> can be cooling means which make it possible for example to cool the dye bath B to approximately <NUM>. At this temperature, the indigo dye has the greatest affinity with the cellulose fibre, thus obtaining a better colour yield, which can be increased further by the application of one or more ultrasound generators <NUM>.

The dyeing machine <NUM> according to the present invention makes it possible to implement an innovative dyeing method which comprises the following monophase operative cycle, which is replicable and is carried out totally automatically. This dyeing method should however be considered as indicative and not compulsory, since it can be adapted to various particular production requirements, as well as to the composition of the colour kitchen and/or to other particular equipment.

After having prepared in the first preparation tank <NUM> the entire quantity of dye bath B necessary to dye a single batch or a plurality of batches constituting an entire lot of yarn, a determined quantity of dye bath B, necessary for a batch, is transferred into the second, auxiliary tank <NUM>. The following steps are then taken:.

For ecological and economic purposes, it should be noted that the used dye baths obtained from dyeing of the individual batches can be recuperated in an appropriate container (not shown), and, subject to titration and topping up of the various components, reused. It will be appreciated that, with suitable adaptations and simplifications, said operative cycle can advantageously also be used with other classes of dyes, different from indigo. It should also be noted that all of the particular characteristics and the above-described technical, economic and ecological advantages of this new machine, with the exclusion of those which relate to dyeing only with indigo, are mostly also valid for dyeing of many fibres with other classes of dyes.

In practice, the dyeing machine <NUM> according to the present invention revolutionises the present system for dyeing of hanks in dyeing cabinets since, unlike these dyeing cabinets, it permits execution of the entire operative cycle in its interior, without moving material, with drastic reductions of the ratio between the weight of the yarn and the volume of dye bath, and reductions of energy consumption, labour, and operative times, chemical products, and above all water. All of this takes place rationally, simply, conveniently, and above all economically and environmentally sustainable. Compared with the dyeing cabinets according to the prior art, the dyeing machine <NUM> according to the present invention is structurally simplified, and although being more complete, convenient and rational, its economic cost is substantially lower.

The dyeing machine <NUM> according to the present invention is also characterized by particular operative versatility and flexibility, since, with the support frame <NUM> rotating, it can dye and treat also garments made of knitwear or of fabric, with all of the above advantages. These processing operations are increasingly in demand, since they can be carried out in short periods of time on untreated garments which are already ready in stock, so as to permit deliveries which are speedy, and consequently in line with the increasingly rapid variations of fashion.

It should be noted that, since the dyeing machine <NUM> according to the present invention is substantially constituted by an apparatus with a cylindrical form, whereas the dyeing cabinets according to the prior art have a parallelepiped form, it is advantageous, and has a much lower economic cost with reference to the structure of the further version which operates under static pressure, which is a necessary condition in order to be able to dye hanks and/or ready-made garments made of synthetic fibres, requiring dye baths with temperatures close to <NUM>/<NUM>. In fact, since it is cylindrical, the dyeing machine <NUM> can be subjected to higher pressures than those which can be obtained within a dyeing cabinet with a parallelepiped form, and can thus reach the above temperatures (<NUM>/<NUM>), with far higher performance levels than the maximum of <NUM>/<NUM> which can be reached in the dyeing cabinets, which are normally pressurised to <NUM> bar.

It has thus been shown that the machine for dyeing of hank yarns and/or ready-made garments according to the present invention achieves the objects previously set out, and in particular provides the following advantages:.

The machine for dyeing of hank yarns and/or ready-made garments thus designed can in any case be subjected to numerous modifications and variants, all of which come within the same inventive concept; furthermore, all the details can be replaced by technically equivalent elements. In practice, any materials, forms and dimensions can be used depending on the technical requirements.

Claim 1:
Dyeing machine (<NUM>) for hank yarns and/or ready-made garments, comprising:
- at least one dyeing apparatus (<NUM>) provided with:
- a casing (<NUM>) enclosing at least one dye compartment (<NUM>); and
- at least one hermetically sealed hatch (<NUM>), which is provided on said casing (<NUM>) and permits access to said dye compartment (<NUM>);
- at least one support frame (<NUM>), which is mounted such as to rotate within said dye compartment (<NUM>) and is designed to rotate, by means of at least one rotation pin (<NUM>), around a central axis of rotation (A) which is horizontal and passing via said rotation pin (<NUM>);
- at least one tank (<NUM>, <NUM>; <NUM>, <NUM>), containing at least one dye bath (B);
- at least one hydraulic circuit (<NUM>), which is connected hydraulically to said at least one tank (<NUM>, <NUM>; <NUM>, <NUM>) and to said dyeing apparatus (<NUM>) in order to supply said at least one dye bath (B) from said at least one tank (<NUM>, <NUM>; <NUM>, <NUM>) to said dye compartment (<NUM>) and vice versa; and
- a plurality of support means (<NUM>; <NUM>, <NUM>) for the hank yarns and/or the ready-made garments, which means are mounted on said support frame (<NUM>) and are accessible via said hatch (<NUM>),
wherein both said casing (<NUM>) and said support frame (<NUM>) have a circular form in vertical transverse cross-section, i.e. a cross-section obtained along a plane orthogonal to said central axis of rotation (A), such that said casing (<NUM>) has a cylindrical frontal wall and that said dye compartment (<NUM>) has a cylindrical form, wherein said hatch (<NUM>) is provided on said cylindrical frontal wall, and wherein said support means (<NUM>; <NUM>, <NUM>) are disposed on said support frame (<NUM>) according to a configuration which is preferably circumferential with respect to said central axis of rotation (A) and are placed in the vicinity of the inner surface of said cylindrical frontal wall, the dyeing machine (<NUM>) being characterized in that said at least one hydraulic circuit (<NUM>) comprises one or more circuits (<NUM>) for supply of nitrogen and air, which are connected hydraulically to said at least one tank (<NUM>, <NUM>) and to said at least one dye compartment (<NUM>), such as to supply nitrogen (N) into said at least one tank (<NUM>, <NUM>) and said at least one dye compartment (<NUM>).