CONTINUOUS DYEING PLANT FOR WARP THREADS COMPRISING AN OXIDATION APPARATUS HAVING VARIABLE AND RECOVERABLE CAPACITY
A continuous dyeing plant for a warp thread including a plurality of dyeing/squeezing groups arranged in line, each of which is provided with a respective impregnation or dyeing tank in which the warp thread is immersed, and an oxidation apparatus that has a plurality of upper and lower return rollers, configured to arrange the warp thread on a plurality of vertical planes parallel to each other, and a support frame having at least one upper strut and at least one lower strut, where a plurality of upper return rollers are mounted on the upper struts, such that at least one part of the lower return rollers is rotatably mounted on at least one respective support device that is movable in the vertical direction between a first operating position, in which the movable support device is placed close to the lower struts to keep the lower return rollers at a maximum predefined distance from the corresponding upper return rollers, and a second operating position, in which the movable support device is placed close to the upper struts to keep the lower return rollers at a minimum predefined distance from the corresponding upper return rollers.
A dyeing plant of threads is provided and, in particular, an oxidation apparatus applicable to continuous dyeing plants, in plane and with indigo dye, of warp threads for denim fabrics. The oxidation apparatus is configured to oxidize the threads passed through the dyeing plant after each single dyeing and with variable and recoverable capacity.
BACKGROUNDDenim is the most produced fabric in the world, since it is used to make jeans. As known, indeed, jeans are trousers of practically universal use and availability.
Denim is produced by weaving a chain of warp threads, already dyed with indigo, with an unbleached weft thread. Both the threads are made of cotton. The warp chains are dyed, continuously, with indigo. Indigo is a dye having very special characteristics, which requires a special method of application. This dye, having relatively small molecules, has very little affinity with cellulose fiber, such as cotton, and for the application thereof it needs not only to be reduced in alkaline solution, but also to be subjected to a plurality of impregnations separated by dehydration and subsequent oxidation with air. In practice, a medium or dark color tone is obtained only by subjecting the thread to a first dye in a suitable tank, immediately followed by many overdyes in successive tanks.
The plants that carry out this particular dyeing should be built respecting certain base parameters, relative to the immersion and oxidation times of the thread. This is to allow the thread to have optimal absorption of the dyeing bath and, after squeezing, a complete oxidation before entering the next tank, so as to be able to “rise”, i.e. darken its color tone. In practice, however, every manufacturer of dyeing plants applies different parameters from its competitors and therefore these parameters are highly variable. Moreover, very often users require specific parameters to adapt the obtainable results to their particular requirements.
In a generic dyeing plant the number of dyeing tanks varies from 6 to 8, the immersion time of the thread in the dyeing bath varies from about 8 seconds to about 20 seconds, whereas the time for the oxidation of the thread itself, after squeezing, varies from about 60 seconds to about 80 seconds. This means that the thread must remain exposed to air for about 60-80 seconds before being reimmersed in the next dyeing tank. This time of exposure to air is repeated for all of the tanks of the dyeing plant.
The average dyeing speed can be considered variable from 25 to 40 metres per minute. Consequently, for every dyeing tank, the amount of thread immersed in the respective dyeing bath is on average equal to about 4-11 metres, whereas the amount of thread exposed to air between one dyeing tank and the next ranges from about 30 to 40 metres.
Thus, taking a standard plant with eight dyeing tanks as an example, the thread passed through just the dyeing tanks and the relative groups of oxidation cylinders can reach a substantial length. The maximum length of the thread, in this case, is equal to 408 metres based on the following formula: [(11 metres×8 tanks=88 metres)+(40 metres×8 oxidation apparatuses=320 metres)]. This amount of thread, with the addition of smaller amounts due to the passing of the other parts of the dyeing plant (pre-treatment and final washing tanks of the thread, sizer to which the dyeing plant is connected, etc.), in reality reaches a total of about 500/600 metres, which contributes to making the plant itself more difficult to control.
A big drawback encountered in conventional dyeing plants is caused by the large amount of thread that is lost at each change of batch. In this operating condition, indeed, the entire aforementioned amount of thread, which constitutes the tail end of the batch of thread, the dyeing of which is finished and which remains in the plant after it has stopped, must be considered lost, since it is not evenly dyed. Similarly, the same amount of thread that constitutes the start of the new bath and that, connected to the tail end thread, replaces it in passing the dyeing plant (carried out at low speed for technical and safety requirements), is also not evenly dyed and must thus be eliminated.
It should be specified that a reduction of the aforementioned amount of thread is already possible in very few plants that have the new dyeing technology in an inert environment, which allows the reduction of the number of dyeing tanks. This dyeing technology in an inert environment is described in documents EP 1771617 B1 and EP 1971713 B1 to the same Applicant. A reduction of the aforementioned amount of thread is also possible in the few plants that have oxidation intensifiers, like for example the one described in document EP 0533286 B1 again to the same Applicant.
However, industrial history tells of the difficulties and reluctance following the introduction of new technologies. Dyeing plants under nitrogen, therefore, by conformity, uniformity of production, technological inertia, particular market conditions, fashion, etc., have also only been manufactured in a few units.
Oxidation intensifiers, on the other hand, have had much greater success, but the number of dyeing plants that are equipped with them represents a negligible part of all operating dyeing plants and also newly produced ones, which mostly still adopt the classic groups of air cylinders as oxidation apparatuses. Oxidation intensifiers have allowed a reduction, not significant but partial, of the amount of thread exposed to air. This reduction of the amount of thread exposed to air is in any case obtained with the application of mechanical apparatuses that require not only a certain economic investment, but also a continuous energy cost and constant cleaning operations of the filters, as well as the necessary maintenance.
Further prior art documents include document U.S. Pat. No. 6,355,073 B1, which however does not illustrate an oxidation apparatus with variable and recoverable capacity, but rather a module for continuously dyeing warp chains with indigo and other dyes, commercially called “Reactor”. Document JP 3706689 B2 illustrates a device for the continuous application of a product on bands of fabric or threads. In practice, a pump feeds the product to a collector, which deposits such a product on a deflector which, in an alternate manner, transfers such a product on the bands. Document DE 4342313 A1 illustrates an indigo dyeing module in an inert environment. Document CN 103938387 A finally concerns a conventional continuous indigo dyeing machine, in cords, with a vaporizer placed at the exit of the dyeing section.
BRIEF SUMMARYIn light of the above, there is clearly a need to be able to drastically reduce the amount of thread exposed to air in oxidation apparatuses, which is the cause of the relative deterioration both during the end of batch operations, i.e. before the stopping of the dyeing plant necessary for the introduction of the new batch of thread, and during the starting operations of the new batch of thread, i.e. when the plant is started up at low speed. This possibility, in the above operations, would lead to a substantial economic saving, prudently quantifiable in the recovery of at least 400/500 metres of warp chain, and moreover it would also give a worthwhile contribution to environmental protection and sustainability.
The purpose of the present disclosure is therefore to make a dyeing plant of threads, in particular an oxidation apparatus applicable to continuous indigo dyeing plants, which is capable of overcoming the aforementioned drawbacks of the prior art in an extremely simple, cost-effective and particularly rational and functional manner.
In detail, a purpose of the present disclosure is to make an oxidation apparatus for continuous indigo dyeing plants that makes it possible to drastically reduce, both at the end of each batch of thread, i.e. before the stopping of the plant for the introduction of the new batch of thread, and at the start of a new batch of thread, the amount of thread exposed to oxidation in air.
In this way there would be the advantage, secondary but not of little importance, of having the possibility, without having to change the pass as standard oxidation apparatuses require, of varying the amount of thread chain exposed to air by oxidation, bringing it to the minimum necessary according to the requirements of the dyeing process, the count of the thread, the work speed, etc., to facilitate the control of the plant. A further advantage involves the possibility of using the oxidation apparatus, suitably complete with the necessary actuator devices, to carry out the adjustment function of the synchrony between one dyeing group and the next, replacing the classic dandy roll, to keep the tension of the thread constant.
This and other purposes according to the present disclosure are accomplished by making a dyeing plant of threads, in particular an oxidation apparatus applicable to continuous indigo dyeing plants.
The characteristics and advantages of an oxidation apparatus for continuous indigo dyeing plants according to the present disclosure will become clearer from the following description, given as an example and not for limiting purposes, referring to the attached schematic drawings, in which:
With reference in particular to
The plant 10 comprises a plurality of dyeing/squeezing groups 12 arranged in line, each of which is provided with a respective impregnation or dyeing tank 14A, 14B, 14C in which a warp thread 100, which advances from left to right with reference to the representation of the plant of
As shown in
The oxidation of the warp thread 100 is carried out in the area of the dyeing plant 10 arranged between the pair of squeezing cylinders 40 at the exit of a first tank 14A and the guide roller 16 associated with the next tank 14B. The oxidation of the warp thread 100 is thus carried out by a suitable oxidation apparatus 20 that comprises a plurality of return rollers 22A, 22B configured to arrange the warp thread 100, which is in continuous movement, on a plurality of vertical planes parallel to one another (see
Conventional oxidation apparatuses 20, for example like the one shown in
The oxidation apparatus 20 according to the present disclosure, schematically illustrated in
In other words, the oxidation apparatus 20 according to the present disclosure is provided with a plurality of movable support devices 30A, 30B, 30C that operate from movable platforms for at least one part of the lower return rollers 22B. Each movable platform 30A, 30B, 30C, suitably guided and tensioned, can rise and fall inside the support frame 24 of the oxidation apparatus 20, thus making it possible to vary the capacity of use of the oxidation apparatus 20 itself and drastically reduce, in the change of batch step of the warp thread 100 (stopping/restarting of the dyeing plant 10), the amount of thread 100 contained in the dyeing plant 10 to avoided discarding it.
With reference to the particular embodiment of
Each movable support device 30A, 30B, 30C of the oxidation apparatus 20 can also be provided with upper struts 26 separate from the corresponding upper struts 26 of the movable support devices 30A, 30B, 30C contiguous to it, so as to make the entire oxidation apparatus 20 modular. In other words, the linear guide uprights 32 of each movable support device 30A, 30B, 30C can be made integral to the lower struts 28 by means of reversible fixing means 46, like for example bolts.
Each movable support device 30A, 30B, 30C of the oxidation apparatus 20 can be provided with at least one movement means 34, operatively associated with the support frame 24 of the oxidation apparatus 20 and with the electronic control unit 50 of the dyeing plant 10. Alternatively, a single movement means 34 or a plurality of movement means 34 can be provided, operatively associated on one side with the support frame 24 of the oxidation apparatus 20 and on the other side, by means of corresponding movement transmission means (not shown but comprising for example belts, chains or transmission shafts), with a plurality of movable support devices 30A, 30B, 30C that are separate from one another.
Each movement means 34 can without distinction be of the pneumatic, hydraulic, electric or mechanical type, or it can comprise a combination of such systems. In the embodiment shown in
The oxidation apparatus 20 according to the present disclosure makes it possible to vary the amount of thread 100 exposed to air for oxidation with a process that has the following steps. During the indigo dyeing process, all of the movable support devices 30A, 30B, 30C of the dyeing plant 10 are normally placed at the bottom, in other words in their first operating position of
By means of a position transducer 48 it is also possible to place one or more movable support devices 30A, 30B, 30C at a predefined intermediate height between the lower struts 28 and the upper struts 26 of the support frame 24. This intermediate height can be set and/or modified automatically and/or manually to increase or reduce the amount of thread 100 passed through the dyeing plant 10, adapting it to possible production requirements.
At the end of each batch of thread intended for dyeing, the warp thread 100 that feeds the dyeing plant 10 is practically all passed through, with the exception of the few metres of reserve that are necessary to tie it to that of the new batch of thread.
In this operating condition all of the traction motors of the warp thread 100 from the driving calandar up to the squeezing cylinders 40 of the first dyeing tank 14A stop, leaving in operation all of the remaining motors of the part of dyeing plant 10 placed downstream of such a first dyeing tank 14A.
The stopping of all of the traction motors of the warp thread 100 that are placed upstream of the first dyeing tank 14A, as well as of the traction motors of the warp thread 100 that belong to the first dyeing tank 14A itself, forces the dyeing plant 10 to be fed with the warp thread 100 passed through the portion of oxidation apparatus 20 placed immediately downstream of the first dyeing tank 14A. Consequently, the first movable support device 30A arranged between the first dyeing tank 14A and the second dyeing tank 14B is lifted proportionally to the decrease in the amount of thread 100 passed through the aforementioned portion of oxidation apparatus 20 placed immediately downstream of the first dyeing tank 14A.
The lifting of the first movable support device 30A continues until the respective second operating position of
The operations described above will be repeated for the second movable support device 30B arranged between the second dyeing tank 14B and the third dyeing tank 14C as well as, in an identical and sequential manner, for all of the next dyeing tanks. The emptying of the end portion of the oxidation apparatus 20, in other words of the last movable support device, will stop all of the remaining motors of the dyeing plant 10 still operating, i.e. those of the washing tanks 44 placed downstream of all of the dyeing/squeezing groups 12.
It has thus been seen that the oxidation apparatus 20 applicable to the continuous indigo dyeing plants according to the present disclosure achieves the purposes highlighted earlier. The clear advantage of being able to recover two times, and thus of being able to use, conservatively, at least 80% of the amount of thread 100 passed through the oxidation apparatus 20, which in dyeing plants equipped with conventional oxidation apparatuses is discarded, is added to with the advantage of a substantial reduction of the time necessary for the change of batch operation.
The fact that the amount of thread 100 contained in the dyeing section is reduced to the minimum, by positioning the movable platforms that constitute the movable support devices 30A, 30B, 30C of the return rollers 22A, 22B of the oxidation apparatus 20 at the maximum upper limit, drastically reduces the time needed for passing the joining knots of the two batches of thread 100 and of the combs that adjust the width thereof, during the change of batch operations, which must be carried out at reduced speed for technical and safety reasons.
Moreover, the same advantages described above and referring to the end of dyeing operations are also obtained in the subsequent starting operations of the new batch of thread 100. These operations are carried out in the opposite direction, i.e. introducing into the dyeing plant 10, at low speed, the new batch of thread 100 with all of the movable support devices 30A, 30B, 30C passed through with the minimum amount of thread 100, in other words in the second operating position of
The oxidation apparatus 20 having variable and recoverable capacity according to the present disclosure can be inserted in any conventional indigo dyeing plant. In the same dyeing plant 10, a variable number of movable support devices 30A, 30B, 30C can also be provided according to requirements.
The oxidation apparatus applicable to the continuous indigo dyeing plants of the present disclosure thus conceived can in any case undergo numerous modifications and variants, all of which are covered by the same inventive concept; moreover, all of the details can be replaced by technically equivalent elements. In practice, the materials used, as well as the shapes and sizes, can be whatever according to the technical requirements.
The scope of protection of the disclosure is therefore defined by the attached claims.
Claims
1. Continuous dyeing plant with a dyeing substance for a warp thread, the dyeing plant comprising:
- a plurality of dyeing/squeezing groups arranged in line, each of said dyeing/squeezing groups being provided with a respective impregnation or dyeing tank into which the warp thread is immersed;
- an oxidation apparatus that comprises a plurality of upper and lower return rollers, which are configured to place the warp thread onto a plurality of vertical planes parallel to each other, and a support frame placed downstream of said plurality of dyeing/squeezing groups, said support frame comprising at least an upper strut and at least a lower strut forming a laterally, downwardly and upwardly open structure to allow the oxidation of the dyeing substance by means of the contact of the dyed warp thread with the maximum possible amount of air, a plurality of upper return rollers being mounted on said at least one upper strut; and
- an electronic control unit,
- wherein at least one part of the lower return rollers is rotatably mounted on at least one respective support device that is movable in a vertical direction between a first operating position, wherein said movable support device is placed at said at least one lower strut in order to keep the lower return rollers at a maximum predefined distance from the corresponding upper return rollers, and a second operating position, wherein said movable support device is placed at said at least one upper strut in order to keep the lower return rollers at a minimum predefined distance from the corresponding upper return rollers.
2. Dyeing plant according to claim 1, wherein each movable support device is vertically moved along a plurality of linear guide uprights, said linear guide uprights being integral at the bottom to a pair of lower struts, parallel to one another, and integral at the top to a pair of upper struts, parallel to one another and to said lower struts, wherein said upper struts and said lower struts, together with said linear guide uprights of each movable support device, constitute the perimeter of a parallelepiped-shaped cage that supports the upper return rollers and the lower return rollers.
3. Dyeing plant according to claim 1, wherein each movable support device is provided with upper struts separated from the corresponding upper struts of the movable support devices that are contiguous thereto.
4. Dyeing plant according to claim 3, wherein the linear guide uprights of each movable support device are made integral to the lower struts by means of reversible fixing means.
5. Dyeing plant according to claim 1, wherein each movable support device is provided with at least one movement means that is operatively associated with the support frame and with the electronic control unit of the dyeing plant.
6. Dyeing plant according to claim 1, further comprising one or more movement means operatively associated on one side, with the support frame and, on the other side, by means of corresponding movement transmission means, with a plurality of movable support devices that are separated from each other.
7. Dyeing plant according to claim 5, wherein each movement means comprises at least one of:
- movement means of the pneumatic type;
- movement means of the hydraulic type;
- movement means of the electric type; and
- movement means of the mechanical type.
8. Dyeing plant according to claim 5, wherein each movement means is of the pneumatic type and comprises a pneumatic actuator cylinder, which is integral with a fixed portion of the support frame, the stem of which is integral with a respective movable support device.
9. Dyeing plant according to claim 8, wherein each stem is integral with a respective movable support device by means of the interposition of a guide rod.
10. Dyeing plant according to claim 1, wherein each movable support device is placed downstream of a first impregnation or dyeing tank and upstream of the following impregnation or dyeing tank.
11. Dyeing plant according to claim 1, further comprising a position transducer configured to place one or more movable support devices at a predefined intermediate height between said least one lower strut and said at least one upper strut of the support frame.
12. Dyeing plant according to claim 1, wherein each movable support device is provided with at least one sensor operatively connected to the electronic control unit of the dyeing plant, said at least one sensor being configured to identify the achievement of the maximum limit of the upper and/or lower end stroke, with reference to the upper struts and to the lower struts of the support frame respectively, by each movable support device.
Type: Application
Filed: May 15, 2017
Publication Date: Mar 28, 2019
Inventor: Francesco RONCHI (SOVICO)
Application Number: 16/087,709