Patent Description:
In the sector of machines for the discontinuous dyeing of spools of yarns, it is known to maintain the spools at least partially immersed in a dyeing bath, which is made to circulate unidirectionally, i.e. from inside the yarn toward the outside, or bidirectionally, i.e. alternating from outside the yarn into the yarn and vice versa, inverting the flow according to preset times.

Various examples of these machines are described in <CIT>.

In particular, it is known to use a closed tank which contains both the spools to be dyed, mounted on corresponding rod-like supports, and the treatment bath.

Properly defined, the spools, which are cylindrical or frustum-shaped, are typically constituted by yarn which is wound around a cylindrical, conveniently perforated tube, and have a weight that is typically comprised between <NUM> and <NUM>.

The closed tank is connected to a reversal device for reversing the circulation of the bath and a main centrifugal pump. A heating coil can be positioned inside the closed tank, and is struck by the flow of the treatment fluid in both directions, according to the condition in which the reversal device is currently in.

The principle of operation of dyeing machines for the discontinuous dyeing of spools is based on making the treatment bath contained in the closed tank pass through the spools bidirectionally.

The treatment bath is, in particular, pushed by the main pump through adapted hydraulic circuits and is forced to pass radially through the yarn that is wound on the perforated tube.

The bath can be forced through from outside the yarn toward the inside or vice versa, according to the condition of the reversal device.

The main pump needs to supply a flow rate that is sufficient to make all of the bath contained in the closed tank circulate through the spools in both the directions allowed by the reversal device.

Therefore the head of the pump must be sufficient to defeat the flow resistances generated by the tubes and by the wound yarn as well.

Typically, it is good practice to make the entire quantity of bath contained in the closed tank circulate through the spools three times in one minute. This in order to ensure the homogeneity of the temperature of the dyeing bath and the same concentration of color on all the surfaces of the yarns.

All this quantity of bath therefore needs to pass through the conduits, which are conveniently dimensioned, through the spools, through the coil and through the bath reversal device.

The flow resistance conditions generated by the spools is a function of:.

Normally a maximum admissible differential pressure is imposed on the main centrifugal pump, for example <NUM> bar, in order to prevent the force generated by the bath in passing through the spool <NUM> from damaging the yarn. Therefore, if the differential pressure tends to exceed the maximum permitted value, the inverter of the pump reduces the number of revolutions, so as to lower the flow rate and prevent the maximum admissible differential pressure from being exceeded. For this reason, the flow rate value of the pump is typically lower than expected, thus compromising the yield of the heat exchange and the capacity to render the bath contained in the closed tank uniform, i.e. compromising the very result of the process.

Therefore, the conventional solution described above has the following drawbacks:.

A dyeing machine for dyeing a mass of yarn or textile fiber according to the preamble of claim <NUM> is already known from <CIT>.

The aim of the present invention is to provide a dyeing machine for dyeing spools of yarns and a corresponding dyeing method that are capable of improving the known art in one or more of the above mentioned aspects.

Within this aim, an object of the invention is to improve the distribution in the closed tank of the dye and/or of the chemical products with which to treat the yarns.

Another object of the invention is to render the temperature uniform and increase the efficiency of heat exchange inside the closed tank.

Another object is to reduce the electricity consumed by the main pump during the process.

Another object of the invention is to render the machine capable of rendering the bath uniform independently of the differential pressure that is generated on the spools of yarn.

Another object of the invention is reduce the dimensions of the hydraulic circuit of the main pump.

Furthermore, another object of the present invention is to overcome the drawbacks of the known art in an alternative manner to any existing solutions.

Another object of the invention is to provide a dyeing machine for dyeing spools of yarns and a corresponding dyeing method that are highly reliable, easy to implement and of low cost.

This aim and these and other objects which will become better apparent hereinafter are achieved by a machine according to claim <NUM>, optionally provided with one or more of the characteristics of the dependent claims.

The aim and objects of the invention are likewise achieved by a method according to claim <NUM>.

The quantity of bath held inside the spools of yarn is substantially changed a certain number of times per minute inside a closed tank which contains the spools of yarn to be processed immersed in a treatment bath, and the remaining quantity of free bath is conveniently mixed inside the closed tank. Then a first pump is used to change the bath inside the spools and a second pump is used to mix the free bath in the closed tank. Furthermore, an external heat exchanger is installed on the circuit of the second pump and is adapted to heat and/or to cool the bath.

Further characteristics and advantages of the invention will become better apparent from the description of a preferred, but not exclusive, embodiment of the machine according to the invention, which is illustrated by way of non-limiting example in the accompanying drawings wherein:.

With reference to the figures, a conventional dyeing machine for dyeing spools of yarn comprises a vertically-extending closed tank <NUM> which contains both the spools <NUM> to be dyed, mounted on corresponding rod-like supports <NUM>, and the treatment bath <NUM>.

In the figure a single spool <NUM> is shown, but typically a plurality of rod-like supports <NUM> are arranged in the closed tank <NUM>, on each one of which a plurality of spools of yarn <NUM> are mounted, one above the other.

The rod-like supports <NUM> are mounted on a base plate <NUM> which distributes to the supports <NUM>, or receives from them, the treatment fluid which is made to circulate by a main pump <NUM> by way of a circuit <NUM> and a reversal device <NUM> for reversing the circulation, in order to carry out the bidirectional change of the treatment bath.

A heating coil <NUM> can be positioned inside the closed tank, and is struck by the flow of the treatment fluid in both directions, according to the condition in which the reversal device is currently in.

The treatment bath is pushed by the main pump <NUM> through the circuit <NUM>, the plate <NUM> and the rod-like supports <NUM> and is forced to pass radially through the yarn, from outside the spools <NUM> toward the inside (in a first configuration of the reversal device <NUM>, shown in <FIG>) and from inside the spools <NUM> toward the outside (in a second configuration of the reversal device <NUM>, shown in <FIG>).

If the quantity of bath contained in the closed tank <NUM> is <NUM> liters, then the flow rate required of the main pump <NUM> is <NUM>/min and that is to say <NUM><NUM>/h in order to be capable of changing the bath <NUM> three times a minute. Normally, the hydraulic head required to enable this quantity of bath to overcome the flow resistances along the circuit is <NUM> mcw (meters of column of water) at the duty point. Therefore, the characteristic required of the main pump is <NUM><NUM>/h at <NUM> mcw.

A dyeing machine <NUM> for discontinuous dyeing according to an embodiment of the invention is illustrated in <FIG> and <FIG>.

The machine <NUM> comprises a closed tank <NUM> which is adapted to be filled at least partly with a treatment fluid so as to form a treatment bath <NUM> inside the closed tank <NUM>. The treatment bath is formed by a treatment fluid which can consist of water or of a mixture of water mixed with a dye and/or with an auxiliary chemical product (for washing, soaping, scouring and/or bleaching).

The closed tank <NUM>, which is usually cylindrical and closed at the ends, can be vertically extended as in the case shown, i.e. with the central axis of the cylinder substantially perpendicular to the ground on which the closed tank <NUM> rests.

In an alternative embodiment, not shown, the closed tank can instead be horizontally extended, i.e. with the central axis of its cylindrical body lying substantially parallel to the ground on which the closed tank rests.

The closed tank <NUM> internally comprises at least one vertically-extended spool-supporting rod <NUM>, of a known type and consisting, preferably, of a rectilinear manifold which is mounted, at a bottom end thereof, on a distribution chamber <NUM> inside the closed tank <NUM> with which the rod <NUM> is in fluid communication.

At least one spool of yarn <NUM>, and preferably a stack of spools of yarn <NUM>, is mounted on each spool-supporting rod <NUM>, and the rod <NUM> is mounted together with the distribution chamber <NUM> inside the closed tank <NUM> so as to keep, during use, the spools <NUM> at least partially immersed in the treatment bath <NUM>.

In the invention described in this application, the term "spool of yarn" <NUM> means any mass of yarn or textile fiber (including in the form of flock or of carded or combed ribbon) wound or not around an axis, such as for example a spool, a spindle, a beam, a cop, a clew, a skein, a top, a muff.

Each spool-supporting rod <NUM> enables the treatment fluid to pass transversely through the spools mounted upon it. In particular, the spool-supporting rod <NUM> is in practice a straight tube which is perforated substantially over all of its lateral surface, in order to radially direct the stream of treatment fluid that axially passes through it.

The distribution chamber <NUM> on the other hand can substantially be an internally-hollow cylinder, with its axis parallel to the axis of the spool-supporting rod <NUM>, and provided on its surface with an opening connected to a respective spool-supporting rod <NUM> and, below, with a single opening for the passage of the treatment fluid.

In the preferred embodiments of the invention, the closed tank <NUM> comprises a plurality of spool-supporting rods <NUM>, which are mounted inside the closed tank <NUM>, vertically parallel to each other on a same distribution chamber <NUM>, or mounted in groups on separate and laterally adjacent distribution chambers <NUM>, which are also contained inside the closed tank <NUM>. A plurality of spools of yarn <NUM> is fitted onto each one of these spool-supporting rods <NUM>, and are therefore stacked on each other along the respective rod <NUM>.

The machine <NUM> further comprises recirculation means which are hydraulically connected to the closed tank <NUM> for moving the treatment fluid between the inside and the outside of the closed tank <NUM>.

In particular, the machine <NUM> circulates the entire treatment bath <NUM> contained in the closed tank <NUM>, through the spools <NUM>, at least three times a minute, in consideration of two requirements.

The first requirement is to change the bath contained inside the yarn of the spools <NUM>. In fact, any treatment that it is desired to be carried out on the yarn must take place with a continuous administration of treatment fluid, i.e. of water and dye and/or water and chemical products. This operation to change the bath contained in the yarn, in substance, makes it possible to bring the chemical products and/or the dye inside the yarn so as to enable a transformation of the yarn (deriving from an operation like scouring, bleaching, coloring, soaping, washing). This transformation in general is a chemical/physical process that occurs in successive steps, for example whitening with hydrogen peroxide and/or soda, washing, coloring with suitable dyes as a function of the composition of the fiber, passage from an acid fluid to a basic fluid or vice versa in order to make chemical reactions happen, and the like. All these transformations are made possible by the change of bath that takes place in the yarn.

The second requirement for changing the entire bath at least three times a minute is to render uniform or homogenize the bath <NUM> contained in the closed tank <NUM>. Every time that, in order to make a transformation happen, chemical products and/or dyes are added, or the state of the temperature is changed inside the closed tank <NUM>, transients are introduced which change the state locally in portions of bath and therefore, in order to prevent the changes in state from happening unevenly, which would produce different shades of the color in the various layers of the wound yarn and/or from spool to spool in the same batch, such transients need to be rendered uniform.

In the present invention, the two operations to change the treatment bath <NUM> and homogenize it are assigned to two different pumps.

In particular, considering that the portion of the treatment bath <NUM> that is retained by absorption by the yarn of the spools <NUM> contained in the bath is known in advance, and the remaining, second portion of the treatment bath <NUM> is therefore also known, it is possible to use a first pump <NUM> which is adapted to only change the bath and which has a flow rate that is such as to change only the aforementioned first portion of the treatment bath <NUM> contained in the yarn a preset number of times per unit of time, for example at least three times a minute.

The first pump <NUM>, for example of the centrifugal type, is associated with a first hydraulic circuit <NUM> which optionally comprises flow reversal means <NUM> and which passes through the spool-supporting rods <NUM> and, if present, the distribution chamber <NUM>.

In the change operation performed by the first pump <NUM>, the direction of the flow can be reversed at least once by way of the flow reversal means <NUM>, which are conventional. The flow reversal means <NUM> can comprise a flow diverter which is actuated by a controlled actuator (as in the case shown in the figures) or they can be incorporated in the first pump, in which case it is a reversible pump.

The flow rate of the first pump, preferably, is comprised between <NUM> and <NUM> times the overall weight of the yarn multiplied by the preset number of times, per unit of time, the first portion of the treatment bath <NUM> is changed. This factor comprised between <NUM> and <NUM> takes account not only of the treatment fluid that remains retained in the spools <NUM>, but also of flow losses owing to leaks or seepage between the cores of the spools (tubes) stacked on each other and also of the fluid that is in the first hydraulic circuit <NUM> associated with the first pump <NUM>, including the gaps between the spools <NUM>.

For example, if the total quantity of treatment bath <NUM> contained in the closed tank <NUM> is <NUM> liters, as in the example of the prior art described above, and if the total load of spools <NUM> is <NUM>, then it can be estimated that the quantity of bath <NUM> absorbed by the spools and the quantity circulating in the circuit of the main or first pump is <NUM> x <NUM> = <NUM> liters, which means that the first portion of the treatment bath <NUM> is about <NUM>% of the total bath <NUM> while the second portion of the treatment bath <NUM> is the remaining <NUM>% approximately.

In order to make <NUM> liters pass through the spools <NUM> three times a minute, the flow rate of the first pump <NUM> must be <NUM> liters/min, i.e. approximately <NUM><NUM>/h, which is less than half the flow rate of the main pump <NUM> of the example of the prior art.

For mixing the second portion of treatment bath <NUM>, there is a second pump <NUM> which is associated with a second hydraulic circuit <NUM> which passes through from outside the closed tank <NUM>.

The flow rate of the second pump <NUM> is such as to make the second portion of the treatment bath <NUM> exit from the closed tank <NUM> and return into it, so as to mix the second portion of the treatment bath, i.e. the portion that is not retained by the spools <NUM> and by the first hydraulic circuit <NUM>. Returning to the previous example, in order to mix the remaining <NUM> liters of the treatment bath <NUM>, the flow rate of the second pump <NUM> is approximately <NUM><NUM>/h.

In this manner, the portion of bath that was not moved by the first pump <NUM> is mixed, thus more effectively and constantly rendering uniform the bath contained in the closed tank <NUM> outside of the spools <NUM>.

The intake inlet of the second pump <NUM> is hydraulically connected to the bottom end of the closed tank <NUM>, so as to withdraw the treatment bath that is located below the region of the spools <NUM>, while the outflow of the second pump <NUM> is hydraulically connected with a heat exchanger <NUM> outside the closed tank <NUM> which is adapted to heat or to cool the treatment bath on the basis of a predefined program for treating the yarn, which is programmed in the control system of the machine <NUM>.

Inside the closed tank <NUM>, in particular in the bottom region below the spool-supporting rods <NUM> and the distribution chamber <NUM>, there is a diffuser <NUM> which is hydraulically connected downstream of the heat exchanger <NUM> along the second hydraulic circuit <NUM> and which consists, preferably, of a substantially annular manifold (i.e. a tubular conduit which is provided with a plurality of through holes on its lateral surface and which is substantially circular if the closed tank <NUM> has a vertical axis or quadrangular if the closed tank has a horizontal axis). The positioning of the diffuser <NUM> is on the bottom of the closed tank <NUM> and is adapted to make it block the flow of the first portion of treatment fluid in both of the possible directions of flow imposed by the flow reversal means <NUM>. In this manner, the first portion of the treatment bath is subjected to a heat exchange following contact with the diffuser <NUM> and, in particular, it is heated if the heat exchanger <NUM> is used to heat the second portion of the treatment bath which passes through the second hydraulic circuit <NUM>.

The annular manifold that constitutes the diffuser <NUM> preferably occupies space in a horizontal direction substantially corresponding to the horizontal extension of the base of the interspace that is left between the outermost spools <NUM> and the vertical inner lateral surface of the closed tank <NUM>, thus allowing the flow of the first portion of bath which enters or exits radially with respect to the spools and which passes through this interspace to go on to strike the diffuser <NUM>.

Finally, the machine <NUM> can comprise at least one tank <NUM> of a dye and/or at least one tank <NUM> of an auxiliary chemical product, for example a product for washing, scouring or bleaching the yarn. In the example shown, the tanks <NUM> and <NUM> introduce their content proximate to the intake inlet of the first pump <NUM>.

In an alternative embodiment, not shown, the tanks <NUM> and <NUM> introduce their content proximate to the intake inlet of the second pump <NUM>, or directly into closed tank <NUM>.

There can also be a tank for preparing the bath <NUM>, which can be used during a step of continuous washing of the yarns. Such tank can coincide with one of the tanks <NUM> and <NUM>, as in the embodiment shown in the figures.

Operation of the invention is evident from the description of the machine <NUM>.

In any case, it entails first of all inserting the spools <NUM> of yarn into the closed tank <NUM>, in particular fitting them onto the spool-supporting rods <NUM> which are mounted on the distribution chamber <NUM> and inserting the assembly into the closed tank <NUM>. The insertion of the assembly constituted by the distribution chamber <NUM>, the rods <NUM> and the spools <NUM> occurs, in the case shown, from above, i.e. by removing the rounded upper cover of the closed tank <NUM> and lowering the structure with the spools <NUM> from above.

Then the closed tank <NUM> is at least partly filled with the treatment fluid used in the first step of the cycle envisaged for the specific yarn used. The filling is such that all the spools <NUM> are at least partially immersed in the treatment bath <NUM>.

At this point, during the first step of the above mentioned cycle, the control system of the machine <NUM> repeats, at least three times a minute, the steps of movement (<FIG>) and reversal (<FIG>).

In the movement step, a pumping is carried out with the first pump <NUM> which moves the first portion of the treatment bath <NUM> along the first hydraulic circuit <NUM>, which is substantially equal to the known portion of the bath <NUM> that is known to be retained by the specific yarn to be treated on the spools <NUM>, optionally increased by a factor comprised between <NUM> and <NUM> on the basis of the configuration of the first circuit <NUM>. In the case shown in <FIG>, in this first step the volume of treatment fluid, under the action of the first pump <NUM>, is sucked in by the distribution chamber <NUM> and therefore by the spool-supporting rods <NUM>, after moving back up along the interspace between the spools <NUM> and the inner lateral surface of the closed tank and after having passed radially through the spools <NUM> from the outside toward the respective rods <NUM>. The flow thus enters the reversal means <NUM> in order to then be fed anew to the closed tank by the first pump <NUM> from the bottom end of the closed tank toward the diffuser <NUM>, modifying the temperature of the flow as a result of contact with the diffuser <NUM> and of mixing with the flow exiting from the diffuser <NUM>, moving back up again in the aforementioned interspace.

In the step of reversing the flow of the first portion of the treatment fluid, the reversal means <NUM> are switched (<FIG>) so as to invert the flow of the first portion of treatment fluid inside the closed tank with respect to the previous step (<FIG>), while the operation of the first pump <NUM> remains unchanged with respect to the previous step. The volume of treatment fluid, under the action of the first pump <NUM>, enters from the bottom end of the closed tank <NUM>, rises in the distribution chamber <NUM> and along the spool-supporting rods <NUM>, passes radially through the spools <NUM> to the outside of them, descends along the interspace between the spools <NUM> and the inner lateral surface of the closed tank <NUM>, flows over the diffuser <NUM> and enters the reversal means <NUM> in order to then be fed anew to the distribution chamber <NUM>.

During the repetitions of the above two steps of movement and of reversal, the remaining, second portion of the treatment bath <NUM> is made to recirculate along the second hydraulic circuit <NUM> through the second pump <NUM>.

The passage through the heat exchanger <NUM> entails a thermal conditioning of the volume of fluid of the second circuit <NUM>, for example a heating thereof, so that the flow exiting to the diffuser <NUM> changes the temperature of the flow that passes through the interspace between the spools <NUM> and the inner lateral surface of the closed tank <NUM> around them.

Once the step of treatment with a first fluid is finished, the control system of the machine <NUM> can carry out other steps such as the introduction of dyes or chemical products originating from the tanks <NUM> or <NUM> or the draining of the treatment bath.

Returning to the numeric example of a treatment bath of <NUM> liters and an overall weight of spools <NUM> of <NUM>, it has been seen that the flow rate of the first pump <NUM> can be approximately <NUM><NUM>/h and the flow rate of the second pump <NUM> can be approximately <NUM><NUM>/h.

Assuming <NUM> mcw of hydraulic head for the first pump <NUM> and <NUM>-<NUM> mcw for the second pump <NUM>, we get a power of <NUM> kW for the first pump <NUM> and <NUM> kW for the second pump <NUM>, for a total of <NUM> kW against the <NUM> kW of the main pump <NUM> of the prior art (at <NUM><NUM>/h flow rate and <NUM> mcw of head).

The saving of electricity that can be achieved by virtue of the present invention is therefore evident (<NUM>% in the specific case).

In addition to the saving of electricity consumed during the process, it can be seen that the invention achieves the intended aim and objects.

A flow rate is made to pass through the spools which is less than half of the flow rate that needs to pass with the machines of the prior art. This makes it possible to be more delicate in the process, in addition to being able to work with a lower differential pressure. Making a greater quantity of bath pass through the same spools necessarily implies applying a greater differential pressure, therefore with a greater physical stress on the yarn.

All of the hydraulic circuit of the first pump <NUM> is consequently smaller, in terms of dimensions, than that of the main pump <NUM> of the prior art. Therefore there are smaller dimensions of the flow diverter <NUM>, smaller pipe diameters, smaller diameters of the heat exchanger <NUM> and a smaller quantity of needless bath in the pipes.

The heat exchanger of the invention operates under conditions of constant heat exchange efficiency, in particular not as a function of the differential pressure of the first pump <NUM>.

The mixing of the treatment bath always occurs in the same way and is not influenced by the differential pressure that is generated on the spools. There is also, therefore, a better uniformity of the entire system.

The tanks of dyes or auxiliary chemical products, in the same way, both for transferring the bath of the closed tank to the tanks and for introducing the chemical products or dyes from the tanks into the closed tank, are provided under conditions of constant operation from step to step and between different batches.

In practice, the materials used, as well as the contingent shapes and dimensions, may be any according to the requirements and to the state of the art.

The present application claims priority from <CIT>.

Claim 1:
A dyeing machine (<NUM>) for dyeing a mass of yarn or textile fiber (<NUM>), such as in the form of spools, spindles, beams, cops, clews, skeins, tops, muffs, which comprises a closed tank (<NUM>) which is adapted to be filled at least partly with a treatment fluid so as to form a treatment bath (<NUM>), and recirculation means (<NUM>, <NUM>) which are connected to said closed tank (<NUM>) in order to move the treatment fluid between the inside and the outside of said closed tank (<NUM>),
said closed tank (<NUM>) comprising internally at least one spool-supporting rod (<NUM>) on which it is possible to fit said mass of yarn or textile fiber (<NUM>), so that, during an operative condition, an amount of said treatment bath (<NUM>) is retained by absorption by the yarn or textile fiber of said mass (<NUM>) and the remaining second portion of said treatment bath remains outside said mass (<NUM>),
said at least one spool-supporting rod (<NUM>) being adapted to allow at least a first portion of the treatment bath, which corresponds to said amount of treatment bath (<NUM>) that is retained by absorption by the yarn or textile fiber of said mass, to pass transversely through said mass (<NUM>),
said recirculation means comprising:
- a first pump (<NUM>), which is associated with a first hydraulic circuit (<NUM>) which passes through said at least one spool-supporting rod (<NUM>),
- a second pump (<NUM>), which is associated with a second further hydraulic circuit (<NUM>) which passes through the outside of said closed tank (<NUM>);
characterized in that it comprises a control system configured to control said first (<NUM>) and second (<NUM>) pumps, in said operative condition wherein said mass is fitted on said least one spool-supporting rod (<NUM>) and both said first (<NUM>) and second (<NUM>) pumps are pumping, so that:
said first pump (<NUM>) has a flow rate that is such as to exchange said first portion of the treatment bath, corresponding to said amount of treatment bath (<NUM>) that is retained by absorption by said mass, a preset number of times per unit of time, and
said second pump (<NUM>) has a flow rate that is such as to make said second portion of the treatment bath exit from the closed tank (<NUM>) and return it into the closed tank (<NUM>), so as to mix said treatment bath (<NUM>).