EP1501974B1

EP1501974B1 - Decatizing apparatus

Info

Publication number: EP1501974B1
Application number: EP03734821A
Authority: EP
Inventors: Pietro Alberto
Original assignee: Biella Shrunk Process Sas Di Pietro Alberto & C
Current assignee: Biella Shrunk Process Sas Di Pietro Alberto & C
Priority date: 2002-01-31
Filing date: 2003-01-28
Publication date: 2006-10-25
Anticipated expiration: 2023-01-28
Also published as: CN100338287C; ITMI20020173A1; ITMI20020173A0; DE60309309D1; DE60309309T2; WO2003064750A1; EP1501974A1; CN1516762A

Description

The present invention relates to an apparatus for continuously decatizing fabrics, knitted fabrics and the like.
As it is known, the decatizing is a fabric finishing operation that aims to improve the appearance, decreasing the thickness and stabilizing the size thereof. This operation can be carried out through an apparatus comprising a heated rotating cylinder, just named decatizing cylinder, and a continuous compressing belt, air- and vapor-proof and realized as a closed ring . The compressing belt is put under tension by some tensioning rollers arranged in such a way that a part of the belt exerts a pressure towards the lateral surface of the decatizing cylinder.
The fabric to be treated, previously moistened, is passed through the compressing belt and the decatizing cylinder and makes a nearly complete revolution around the latter. As a result of the contact between the moist fabric and the heated decatizing cylinder, a certain amount of vapor develops, which can not diffuse outside because of the impermeability of the compressing belt, and thus goes under pressure as if in an autoclave.
The main parameters for the efficacy of the decatizing operation are the temperature of the decatizing cylinder, the permanence time of the fabric on the cylinder and finally the degree of the compression exerted on the fabric.
As concerning the first parameter, since the decatizing cylinder is normally heated from the inside with vapor or diathermic oil, its temperature is easily adjustable.
However, as regards to this, a first inconvenience of the known decatizing machines lies in the fact that the degree of the humidification of the fabric has to be rigidly fixed as a function of said temperature of the cylinder. In fact, if for a given temperature the fabric were excessively moistened, at the end of the treatment the fabric would be still wet. Moreover, since the compressing belt can not be passed through by vapor, the problem can not be solved either by extending the treatment duration, because in this way the emitted vapor would be very much, but it would remain imprisoned in the interspace between the cylinder and the compressing belt until the end of the treatment. Consequently, the fabric coming out from the interspace would result in any case wet because of the condensate. On the other hand, if the fabric were too little moistened, the obtained results would be insufficient.
As regards the other two mentioned parameters of the decatizing treatment, these can not either be freely modified since, to increase the permanence time of the fabric on the cylinder, it is necessary to decrease the treatment speed or to use a cylinder with a larger diameter.
However, the first solution is not suitable for the present industrial requirements that, on the contrary, impose always faster rhythms of production.
If, on the contrary, a decatizing cylinder with a very large diameter would be used, tension of the compression belt being equal, the contact surface between compressing belt and fabric would increase and consequently the compression exerted on the fabric unit would decrease. On the other hand, the traction applied by the tensioning rollers on the compressing belt can not be increased beyond fixed maximum values. Moreover, to obtain a very high traction, a very complex system of the compressing belt tensioning would be necessary, which furthermore deteriorates rapidly because of the force to which it is subjected.
In some known decatizing apparatuses, such as that described in DE2727514 patent, the tensioning roller that precedes the cylinder in the proceeding direction of the fabric is heatable independently of the cylinder.
However, this arrangement does not solve any of the above mentioned drawbacks, but has the only object to pre-heat the compressing belt to allow the user to apply an heating on both sides of the fabric subjected to the treatment, and thus to avoid undesired condensate effects due to different temperatures between the front and the back of the fabric.
US 5.052.069 patent describes a decatizing process wherein the fabric is treated on two decatizing machines placed in series, each of which comprises a fabric humidifying device and a decatizing cylinder with a relevant compressing belt kept in tension by means of tensioning rollers. The temperatures of the two decatizing cylinders can be adjusted independently one from the other, and the humidifying devices can be settled in such a way that the part of the fabric going into the first decatizing machine has a humidity content different from the part going into the second decatizing machine.
This process gives the opportunity to vary the parameters of temperature of the cylinder and of humidification degree of the fabric according to the needs. Moreover, since the decatizing is repeated twice, the efficacy of the treatment is undoubtedly better than that obtained with the known processes.
However, an inconvenience of this process lies in the high cost thereof caused by the utilization of two different decatizing apparatuses. In particular, it is to be noticed that the utilization of two apparatuses means not only a high starting investment, but also a high maintenance cost, especially concerning the replacing of the compression belts that are very expensive and must be periodically replaced.
The object of the present invention is therefore to provide a decatizing apparatus free from these drawbacks. This object is achieved with a decatizing apparatus whose main features are specified in the first claim and other features are specified in the following claims.
A first basic advantage of the present apparatus lies in the fact that, thanks to the plurality of decatizing cylinder of which it is provided, it allows to obtain fabrics of a better quality with respect to the known apparatuses, both in terms of aesthetic aspect and of dimensional stability.
The temperatures of the different decatizing cylinders can be independently adjusted as well as the humidification degrees of the fabric in the different manufacturing steps. This allows to select and to set optimal temperatures and humidification degrees according to the kind of fabric to be treated, the thickness thereof and the desired particular effects.
A further advantage of the decatizing apparatus according to the present invention is that it allows to obtain very high velocities of production, with following advantage from the economic point of view.
Another advantage of the apparatus according to the present invention is that it comprises only one compressing belt, whose tensioning is obtained without the necessity to turn to complex tensioning systems and exerts a high tension on each of the decatizing cylinders.
A further advantage of the apparatus according to the present invention is that it has not only a starting cost lower than that of two or more separated apparatuses, but has also only one compressing belt which, even if it is lightly longer, it costs only a little more than a shorter one, necessary for an apparatus having a single cylinder.
Further advantages and features of the decatizing apparatus according to the present invention will be clear to those skilled in the art from the following detailed description of one embodiment thereof with reference to the only attached drawing, that shows schematically a vertical sectional view of the apparatus according to the present invention.
As it is shown in figure 1, the apparatus for continuously decatizing fabrics according to the present invention comprises in a known way only one closed-ring compressing belt, carried out with a material extremely resistant to traction and substantially gas- and vapor-proof. This belt may even be only partially impermeable, in the sense that it is passed through by vapor with great difficulty.
Said compressing belt is put under tension by a plurality of tensioning rollers 2, 3 and 4. Between these, roller 4 is the traction roller and it is pushed downwardly with the maximum force allowed, while at least one of the rollers 2 and 3 is motorized.
According to the invention, the apparatus further comprises at least two rotating and heatable cylinders 5, towards which said belt 1 exerts the compression of a fabric 6. Said cylinders 5 are suitably arranged among pairs of tensioning rollers 3 and have a diameter preferably smaller than 65 cm. Moreover, to obtain a higher efficacy of the decatizing treatment, they are preferably at least three.
In fact, since with equal tension exerted on the compressing belt 1 the resulting pressure on each of cylinders 5 is equal to that exerted on only one cylinder of the same diameter arranged in the apparatus, utilizing more cylinders, a compression of the fabric of the same amount of that maximum applicable by the known apparatuses, but a prolonged treatment time, is obtained. In particular, with a number of cylinders equals to n times that of an apparatus comprising only one cylinder.
Said cylinders 5 are heated preferably independently one from the other by means of vapor or diathermic oil. As mentioned above, the possibility to modulate the temperatures of the different cylinders at the different humidity degrees of the fabric in the different steps of the treatment allows to obtain optimal decatizing results, without risking the fabric to be still wet when coming out from the last cylinder.
The apparatus according to the present invention may further comprise one or more suction hoods 7 arranged right after the rotating heatable cylinders in the fabric advancing direction. Hoods 7 are suited to sorb part of the aqueous vapor released by the same fabric, helping thus the gradual drying of the fabric during the treatment. In the apparatus according to the present embodiment of the invention, that comprises three rotating and heatable cylinders 5, said suction hoods are two.
The decatizing apparatus according to the present invention comprises further at least one humidifying device (not shown in the figure) arranged before the first cylinder 5 in the fabric advancing direction.
Possible changes and/or additions may be made by those skilled in the art to the here described and illustrated embodiment without departing from the scope of the same invention. For example, the tensioning roller 3 preceding the first cylinder 5 in the fabric advancing direction can be heated independently from the cylinder.

Claims

An apparatus for continuously decatizing fabrics comprising a closed-ring compressing belt (1), at least partially vapor-proof, tensioned by a plurality of tensioning rollers (2, 3, 4), characterized in that it comprises at least two heatable rotating cylinders (5), arranged between pairs of tensioning rollers (3), towards which said belt (1) carries out the compression of a fabric (6).
An apparatus according to claim 1, characterized in that said compressing belt (1) is substantially vapor-proof.
An apparatus according to claim 1 or 2, characterized in that it comprises at least one suction hood (7) arranged right after a heatable rotating cylinder (5) in the fabric (6) advancing direction and suited to sorb part of the aqueous vapor released by the same fabric.
An apparatus according to one of the previous claims, characterized in that said heated rotating cylinders (5) are three.
An apparatus according to one of the previous claims, characterized in that said cylinders (5) are heated independently one from the other.
An apparatus according to claim 4 or 5, characterized in that said suction hoods (7) are two.