Apparatus for the treatment of piece goods

Description Technical field

The present invention relates to an apparatus for the treatment of piece goods according to the characteristics described in the preamble of the main claim. In particular, the apparatus of the invention finds a preferred application in the processes of piece-dyeing and in the processes of large capacity washing, as required by applications in the industrial, hospital or naval field. Technological background

In the technical field of reference of the present invention, conventional apparatuses are known for piece-dyeing, comprising a casing on the bottom of which the dye bath is arranged and within which a rotating basket with a perforated outer wall is mounted, partially immersed in the dye bath. The piece goods to be dyed are admitted into the perforated basket and are set in gentle rotation to facilitate the mixing of the piece goods in the dye bath.

Apparatuses have recently been developed for so-called "high speed" dyeing, in which the rotating basket is set, in some phases, at a rotation speed such that the piece goods are kept pressed by centrifugal force against the walls of the basket. In this way the piece goods to be dyed are alternately impregnated with dye, in the absence of centrifuge, and wrung out, in the centrifuge phase, as in the washes performed by normal domestic washing machines. In these apparatuses, however, high levels of vibration are found in the centrifuge phase, due to the impact of

the piece goods and of the blades against the bath, which simply maintaining the bath at low levels is not sufficient to eliminate.

A first solution to this problem provides for the level of the bath to be maintained at a level below that of the rotating basket so as to avoid any interference with same during its rotation. In this case, the bath is introduced into the basket via a feed circuit open at the axis of rotation of the basket.

However, these apparatuses also have some limitations, in particular there is found to be a not very uniform distribution of the dyeing liquid sprayed within the basket, owing to the lateral positioning of the point of admission of the liquid. Description of the invention

The problem underlying the present invention is that of providing an apparatus for the treatment of piece goods which is structurally and functionally designed to remedy the limitations mentioned above with reference to the prior art cited.

Within the scope of this problem it is an aim of the invention to provide an apparatus for the treatment of piece goods in which it is possible to admit into the rotating basket liquid compounds useful for the treatment of the piece goods, in a more effective manner compared with the known apparatuses.

This problem is solved and this aim is achieved by the present invention by means of an apparatus for the treatment of piece goods, produced according to the following claims. Brief description of the drawings

The characteristics and advantages of the invention will become clear from the detailed description of a preferred exemplary embodiment thereof, illustrated by way of non-limiting example with reference to the appended drawings, in which: - Figure 1 is a diagrammatic view in front section of an apparatus for the treatment of piece goods which is produced according to the present invention,

Figure 2 is a view in lateral section of the apparatus of Figure 1,

Figure 3 is a perspective view on an enlarged scale of a first component of the apparatus of Figure 1,

Figure 4 is a diagrammatic sectional view of the component of

Figure 3,

Figures 5 to 8 are front views of a second component of the apparatus of Figure 1 in respective alternative embodiments, - Figure 9 is an alternative embodiment of a further component of the apparatus of Figure 1. Preferred embodiment of the invention

In the drawings, the reference 1 indicates as a whole an apparatus for the treatment of piece goods, which is produced according to the present invention.

The apparatus 1 comprises an outer casing 2, generally cylindrical, on which is mounted a basket 3 with perforated outer wall, also cylindrical.

The basket 3 is supported by a shaft 4, not passing inside the basket, and by means of which the basket is set in rotation about its own axis X, via drive means which are conventional per se and not shown in the drawings.

On the outer wall of the rotating basket 3, three blades 6 are arranged at a pitch, projecting radially towards the inside of the basket, so as to move the piece goods to be treated 5 that are placed inside the rotating basket.

On the bottom 2a of the casing 2 a tank 7 is further provided for collecting and containing a bath 8 for treating the piece goods 5, and the level of which is maintained at a rate such as not to interfere with the basket 3. On the bottom of the tank 7 a discharge valve 7a is provided.

The apparatus 1 comprises a circuit 10 for feeding the bath 8, collected in the tank 7, into the rotating basket 3. The feed circuit 10 comprises a pipe 11 connecting the tank 7 to a recirculating pump 12 and a delivery pipe 13 connecting the pump 12 to an inlet aperture 4a of the rotating basket 3, provided at the axis X, on the opposite side from the shaft 4. The circuit 10 is completed by a bypass pipe 14 regulated by a valve 15 and extending between the delivery pipe 13 and the tank 7, and also by respective shutoff valves 16, 17, provided on the pipes 11 and 13.

According to a first aspect of the present invention, the feed circuit 10 further comprises nebulising means arranged at the inlet 4a of the rotating basket 3 for nebulising the bath 8 immediately before being introduced into the basket 3.

Nebulising may be effected by various methods; however it is preferred that the nebulising means comprise a turbine pump 20, illustrated in detail in Figures 3 and 4, driven by a motor 21 via a drive belt 22. The motor 21 is advantageously controlled by an inverter, not shown, capable of regulating the rotation speed of the motor, and consequently of

the turbine pump 20, between a minimum of 120 and a maximum of 9000 revolutions per minute.

The turbine pump 20 comprises a chamber 23 in which a delivery aperture 24 is provided, directly opposite the inside of the basket 3, and a plurality of inlets 25 for the entry into the chamber 23 of the bath 8 and/or of other liquid or gaseous compounds mentioned in more detail hereinafter.

The pump 20 further comprises a drive shaft 26, supported on bearings 26a and connected at a first of its ends to the belt 22. Fixed to the opposite end of the shaft 26 by keying or screwing are a turbine 27, a breaking disc 28 and a diffuser cone 29, all placed within the chamber 23.

The turbine 27 has blades 30 configured to impart an axial thrust to the fluid present in the chamber 23 towards the delivery aperture 24.

The breaking disc 28 has the function of breaking the continuity of the liquid forced against it by the turbine 27 in order to transform it into droplets of extremely small size, so as to form almost a mist, and, for this purpose, has a plurality of through holes 31 or recesses 32 at its peripheral edge. Figures 5 to 8 illustrate respective alternative embodiments of the breaking disc 28, in which are provided semicircular peripheral recesses (Fig. 5), a pair of diametrically opposed elongated recesses (Fig. 6), square peripheral recesses combined with circular holes (Fig. 7) and, finally, radial elongated holes alternating with rectangular holes (Fig. 8). The diffuser cone 29, on the other hand, has the function of guiding the admission of the nebulised liquid inside the rotating basket at a preselected angle of entry.

Figure 9 shows an alternative embodiment of the turbine pump 20 in which a single impeller 90 performs all the functions assigned both to the blades 30 of the turbine 27 and to the breaking disc 28 and to the diffuser cone 29 of the preceding example. The impeller 90 is keyed and locked in rotation on the shaft 26, in proximity to the delivery opening 24 and has a plurality of radial blades 91, substantially perpendicular to the axis of the shaft 26, of substantially constant cross-section and provided on both sides with grooves 92 which receive and guide the flow of liquid to be nebulised in a radial direction, such that nebulisation, besides having an advancement component which proceeds coaxially with the shaft 26, has a substantially radial component forming a very open nebulised jet which involves the entire rotating basket, including the portions thereof immediately behind its radial shoulders. This configuration has proved particularly effective for the diffusion of gases and in particular of ozone in the nebulised liquid, since it permits a gas concentration in the bath significantly higher than that otherwise obtainable, as explained in greater detail hereinafter.

According to a preferred embodiment of the invention, connected to the turbine pump 20 via lines 33 that can be interrupted by metering valves 34 are one or more external reservoirs, containing liquid or gaseous compounds different from the bath 8 and which are admitted into the rotating basket 3 for the treatment of the piece goods 5. The various reservoirs, hydraulically separated from the casing 2, and therefore in fact disconnected from the circuit for recovery and recirculation of the bath 8, are normally outside the apparatus 1, on which suitable attachment means

will be provided for the lines 33, but may also be positioned within it.

The reservoirs may comprise a boiler 35 for generating steam, an oxygen cylinder 36, an ozone cylinder 37 and reservoirs 38, 39 for containing auxiliary liquid compounds suitably selected on the basis of the specific treatment to be imparted to the piece goods 5.

Among the most representative auxiliary compounds can be mentioned as an example anti-desizing compounds, useful in the treatment of piece goods in denim fabric, finishing compounds, softening compounds, sequestrating compounds, acid solutions and bisulphite-based solutions.

Advantageously, the lines 33 for connection to the reservoirs 35-39 are attached to one or more inlets 25 provided on the turbine pump 20. In this way, the liquid or gaseous compounds which are admitted into the rotating basket 3 are passed through the turbine pump 20, by means of which they can be mixed to the optimum degree with one another or with the bath 8, and or nebulised so as to be dispersed effectively within the basket 3.

The operation of the apparatus 1 is as follows.

The piece goods 5 are inserted into the basket 3 which is set in rotation while the bath 8 suitable for the treatment to be carried out is fed in.

It will be noted that the type of treatment carried out may be a dyeing process, or also the washing of clothing, tablecloths or linen, or washing combined with sterilisation, necessary for example in the hospital field.

The level of the bath 8 in the tank 7 is maintained at a level below the rotating basket 3, such that this may be set in rotation at any desired speed, even of the order of hundreds of revolutions per minute, without incurring problems deriving from the impact of the piece goods with the bath. The duration of the various treatment phases, the control of the basket in rotation, and also its speed and its direction of rotation, are controlled by a suitably programmed control centre.

The bath 8 is then fed into the rotating basket 3 by means of the feed circuit 10, and owing to the provision of the nebulising means is admitted into the basket 3 in nebulised form, with the size of the droplets such as to allow them to remain suspended in the air for sufficient time to be distributed substantially uniformly over the entire internal volume of the basket 3 before coming into contact with the piece goods 5. In this way, zones having a low bath concentration and zones having a high bath concentration are avoided. The dimensions of the droplets primarily depend on the speed of rotation of the turbine 27 and on the configuration of the holes or of the recesses of the breaking disc 28, or, alternatively, on the speed of rotation of the impeller 90.

In order to obtain the desired nebulising effect, it is possible to act on the number of rotations of the turbine pump 20, by regulating the inverter which controls the motor 21. It has been found that in order to obtain a nebulising effect sufficient to admit the bath homogeneously into the basket 3 it is sufficient for the rotation speed of the turbine pump 20 to be more than 1000 revolutions per minute, while an optimal nebulising effect is obtained with a rotation speed of between 2000 and 3000

revolutions per minute. If desired, it is of course possible to reduce the number of revolutions of the turbine pump 20 so as to obtain a "rain effect", with drops of larger size.

The liquid fed into the basket 3 comes into contact with the piece goods 5 and emerges from the perforated outer wall of the basket 3, in order then to be collected again in the tank 7. The effect connected to the treatment of the piece goods with the bath is particularly effective in the centrifuging phases, in which the liquid is forced through the fibres of the piece goods by the centrifugal force developed by the rapid rotation of the basket 3.

It will be noted that the apparatus 1 also makes it possible to introduce, together with or separate from the bath 8, one or more liquid or gaseous compounds contained in the reservoirs 35-39.

With regard to the gaseous compounds, steam issuing from the boiler 35 may be admitted in order to effect the sterilisation of the piece goods, or oxygen, necessary for certain dyeing processes or for decolorising. These compounds in the gas phase may be introduced alone or mixed with the bath 8, according to requirements.

An important, although unexpected result was found in the treatment of piece goods by means of ozone.

The use of this gaseous compound is mainly intended for operations of sterilisation of the piece goods and it is introduced into the bath by bubbling. In the past, ozone was used also for indigo decolorisation treatments (for example in the case of denim fabric), by introducing the ozone into the bath via a Venturi-type diffuser; however the result led to a

greyish coloration which did not meet with market tastes. For this and other reasons, nowadays the decolorisation of indigo from denim fabrics is mostly carried out with the aid of chemical additives, for example enzyme- based, suitably introduced into the bath. The Applicant conducted a series of tests of decolorisation of the indigo from piece goods made of denim fabric by admitting ozone into the bath 8 at the turbine pump 20 which, in the specific case, was equipped with the impeller 90 described previously with reference to Figure 9. The tests gave important and completely unexpected results. The ozone was admitted into the bath with full recirculation, at a relatively low temperature, preferably between 35 ⁰ C and 40 ⁰ C.

After a treatment time of only 20 minutes, the ozone was eliminated from the bath by increasing the temperature for a limited time (to about 7O ⁰ C) and introducing reducing agents, for example sodium hypochlorite. Surprisingly, the piece goods obtained by the treatment turned out light blue in colour, as required by the market, and not greyish, like the piece goods obtained with the conventional decolorisation treatments with ozone.

A further important advantage obtained by the decolorisation treatment with ozone arose from the fact that the piece goods turned out particularly soft, making it possible to avoid treatment with softener, normally provided for in the standard decolorisation treatments.

The surprising efficacy of the ozone when used in decolorisation treatments with the apparatus of the invention can probably be attributed to the large surface area of contact between the ozone and the bath,

determined by the nebulisation induced by the turbine pump 20, which allows high and rapid absorption of the gas within the liquid phase. In fact, an ozone concentration was found in the bath which was around 3 times that obtained with the conventional methods of ozone introduction into a bath.

The indigo decolorisation treatment carried out according to the above-mentioned procedure makes it possible to obtain important advantages compared with the conventional procedures.

First of all, a great saving is obtained in terms of water consumption of the bath, up to around 30%, of treatment times, around 20-30 minutes as against the 90-120 minutes of a conventional treatment with chemical additives, and of energy, inasmuch as the decolorisation treatment with conventional chemical additives requires bath temperatures of the order of around 6O ⁰ C, as against the 35-4O ⁰ C used. With regard to the liquid compounds, it will be appreciated that these may also be admitted into the rotating basket 3 separately from the bath 8, in nebulised form. This allows the apparatus 1 to provide important advantages compared with the conventional apparatuses. In fact, for example, it is possible to introduce into the basket 3 pure softening compound, which in nebulised form is homogeneously dispersed on the piece goods 5. In the pure form, that is, without means preventing dissolution in water, the softener has a much more efficient action and a smaller quantity thereof can be used.

A second example of application of liquid compounds, which proved particularly advantageous, consists in the introduction into the basket 3,

via the turbine pump 20, of a finishing compound comprising an aqueous solution of polymer, for example polyurethane-based or acrylic-based, for imparting a "plasticised" effect to the piece goods. This effect is particularly sought after for "jeans" and is conventionally carried out by means of spraying with an aqueous solution of polymer on the article slipped onto a suitable dummy. This operation (hereinafter referred to as "resin-coating") is expensive however, inasmuch as it is carried out manually, and is tricky because of the difficulty of distributing the solution uniformly. Through the admission into the basket 3 of an aqueous solution as described above, preferably by adding it drop by drop into the turbine pump 20, it is possible to obtain particularly uniform resin-coating of the piece goods, without it being necessary to have recourse to an operator and also providing significant savings in terms of solution used, from 50% to 70%.

The present invention therefore solves the problem mentioned above with reference to the prior art cited, at the same time offering many other advantages, including the possibility of introducing liquid or gaseous compounds, as shown previously, which are much more effective in their action on the piece goods being treated, and that of obtaining significant savings in terms of water consumed, time and energy.