HK1163761B - Machine and method for the combined mechanical and heat treatment of fabrics, especially knitted fabrics - Google Patents

Description

Machine and method for the combined mechanical and thermal treatment of fabrics, in particular knitted fabrics

Technical Field

The invention relates to a machine and a method for the combined mechanical and thermal treatment of textiles to provide dimensional recovery and hand effects, in particular for the continuous or discontinuous treatment of knitted textiles.

Background

It is well known in the textile industry that it is a hard regulation that fabrics maintain their dimensional stability even after cutting, wearing and general cleaning and washing treatments. This applies in particular to knitted fabrics, the nature of which makes them more likely to lose their dimensional stability than other fabrics.

To this end, the fabric finishing process uses various devices and treatments to improve the dimensional recovery of the fabric so that this value is as close as possible to the maximum that the fabric will have during the future washing and drying treatments required to clean a set of garments cut from the fabric.

Among the treatment methods that are currently possible, the most commonly used treatment methods are basically the following:

passing through a freeze dryer (free dryer) in which an open-width, moist or moistened fabric is continuously overfed on a conveyor belt moving through a drying tunnel;

passing through a compacting machine where the open-width, moistened and heated fabric is continuously mechanically forced to recover its length;

drying takes place in a drum dryer, in which the fabric in rope form is discontinuously loaded into a rotating drum dryer and heated by hot air.

The first and second types of treatment methods are not particularly effective and in many cases, it is necessary to perform both treatments of one treatment method immediately after the other treatment method to achieve acceptable results.

The third prior art treatment (i.e. drum drying) is the most effective limiting condition to date and is often used as a reference.

However, drum drying has serious disadvantages: the use of rope fabric is discontinuous, may be only marginal at a time and has knotting and wringing problems, does not provide uniform quality, and, ultimately, is labor intensive.

The above-mentioned treatment methods, particularly when applied to knitted fabrics, are difficult to eliminate the stresses generated in the fibres during knitting, which means that obtaining a dimensionally recovered and very stable fabric can be a problem.

Methods for assisting in the relaxation of the fabric include vibration or beating to reduce friction between fibers and other surfaces in contact with the fibers.

The patent documents GB1178270, GB1304733, EP148113a1, EP130342a2, US4219942 describe machines equipped with a vibrating conveyor belt for fabrics. The elasticity of the belts in these machines prevents the vibrations from being adequately transmitted to the fabric.

Patent document GB2103670 describes an apparatus and a method for relieving stresses in a fabric ready for further processing, which is made into a roll or a web. In one example described, the fabric is deployed in such a way that: a portion thereof is relaxed and placed on the vibration plate.

Document GB879483 describes an apparatus for vibrating a damp fabric in a drying zone using a vibrating grid. The amplitude of the vibration applied to the fabric is gradually reduced in the direction of feeding of the fabric.

Document FR1024514 describes a method for relieving the stress of a fabric, in which the fabric is unwound and passed over a vibrating support. Alternatively, the fabric may be laminated to the vibration table. To increase the efficiency of the treatment, the fabric can be loaded with a greater weight.

Document US3594914 describes a device comprising at least one inclined vibrating plate on which the fabric slides and is exposed to a heating jet.

None of the above mentioned solutions is entirely satisfactory, since the vibrations are applied to the fabric surface in an unfolded form or with moderate pleating.

While this determines a reduction in friction between the fibers, it limits the acceleration that is transmitted to the fibers.

In other words, the inertial forces generated and acting on the fibers are not sufficient to restore dimensions and stabilize the fabric to a good degree.

Disclosure of Invention

It is therefore an object of the present invention to provide a process for treating fabrics, continuously or discontinuously, in open width, which allows drying of fabrics, in particular knitted fabrics, while obtaining the effects of recovery, bulking and relaxation of improved hand and dimensional stability.

To achieve this object, the present invention provides a machine and a method according to the appended claims, in which the fabric is treated by a specific combined action of heat and mechanical vibrations.

The advantage lies mainly in the fact that the treated fabric does not exhibit residual tensions due to elastic or plastic deformations which are recovered by the combined treatment and therefore do not cause dimensional instability during subsequent processes.

These and other advantages will be better understood from the following description with reference to the drawings showing a preferred non-limiting embodiment of the invention.

Drawings

In the drawings:

figure 1 schematically shows a machine for discontinuously treating a fabric according to the invention;

FIG. 2 is a schematic perspective view of a preferred embodiment of the machine of FIG. 1;

figure 3 schematically shows a machine for continuously treating a fabric according to the invention;

figure 4 schematically shows another embodiment of the machine for the continuous treatment of fabrics according to the invention.

Detailed Description

Fig. 1 shows a first embodiment of the machine for the discontinuous combined mechanical and thermal treatment of a fabric T according to the present invention. To better illustrate the main components of the machine, the protective walls are not shown.

The machine comprises a rigid vibrating platform 2, preferably in the form of a tub, and a drying tunnel 16, the drying tunnel 16 being equipped with a hot air distributor 8 fed by a fan 10. Electrically driven rollers 5, 6 are provided for picking up the fabric T from the vibrating platform, passing it through the drying tunnel and returning it to the vibrating platform.

According to the invention, the fabric T passing instantaneously and instantaneously over the oscillating platform 2 is in the form of a substantially compacted mass 3, except for the portion thereof that is picked up from the oscillating platform, unrolled and passed through the drying tunnel, and then placed again on the oscillating platform.

The oscillating platform 2 is mounted on a visco-elastic suspension element 12 and the oscillating platform 2 is oscillated by a crank-slide mechanism of a type known per se.

In the embodiment shown, the oscillating platform 2 has a flat surface for supporting the fabric, but it is also conceivable to have other shapes, for example curved or polygonal.

The vibration or oscillation is preferably vertical or has a significant vertical component.

In particular, the amplitude and frequency of the oscillations are induced in such a way that the acceleration applied to the fabric is greater than the gravity, so as to shake the whole mass of fabric, and not just the part in direct contact with the oscillating platform 2, as in the known systems of the vibrating belts of the prior art.

For example, the peak-to-peak amplitude of the vibration or oscillation may be between 20mm and 60mm, and the frequency may be between 5Hz and 15Hz, or more preferably, between 5Hz and 10 Hz.

The heating system 8 is preferably of the hot air type, the air being partly recirculated if necessary.

To improve the efficiency of the treatment, the fabric T should initially be in a wet or damp state.

The heating means 9 can be arranged for acting on the block 3 of fabric subjected to the action of vibrations.

Figure 2 shows a preferred embodiment of the machine for discontinuous treatment of knitted fabrics according to the present invention.

The substantially compacted mass 3 of fabric T to be treated is placed on the oscillating platform 2. A heated tunnel comprising a pair of hot air distributors, an upper distributor 8a and a lower distributor 8b, is mounted above the vibrating platform.

A mechanical levitation and vibration system 12 powered by an electric motor 13 resiliently supports the vibration platform 2 and imparts vertical oscillations to the vibration platform 2.

The fabric is sewn end to form a closed loop that continuously circulates in the machine.

In practice, the fabric is picked up from the oscillating platform by the roller 5 (see arrow 4a), returned to the oscillating platform by the roller 6 (see arrow 4b) after being placed on the conveyor belt 7 and passing through the drying tunnel formed by the distributors 8a and 8 b.

The hot air fed by the distributors 8a and 8b into the drying tunnel by means of the fan 10 and heated by the direct or indirect heating system 15 can be partly recirculated or partly refreshed by means of the exhaust fan 11 according to a set flow rate.

The filter 14 intercepts all the air moved by the recirculation fan 10 and by the exhaust fan 11, thus preventing air fluff from accumulating in the machine and/or leaking through the exhaust channel.

Fig. 3 and 4 show an embodiment of a machine for continuously treating a fabric T in open width.

In fig. 3, the fabric in the form of a substantially compacted mass is continuously fed onto a first oscillating platform 18 and is thus transferred by the rollers 17 through the heated tunnel 16 to a second oscillating platform 19, from which it is continuously conveyed outside the machine.

Advantageously, this embodiment makes it possible to apply an alternating movement to the fabric between the two oscillating platforms at a suitable speed higher than the speed at which the fabric is fed into the machine and conveyed outside the machine, in order to maintain a constant fabric load in the machine, but to increase the length of time for which the fabric is held in the machine in the desired quantity.

Fig. 4 shows three consecutive vibrating platforms 18, 19, 20 alternating with two drying tunnels 16, as an example of a modular plant using any number of vibrating platforms and drying tunnels 16 to perform consecutive processes in open width at proportionally higher production speeds.

As shown, each vibration table may be equipped with a heating element 9 mounted above it. In addition, the fed fabric can be conveniently preheated and output thermoset by a suitable additional heating system, of the hot air type, such as drying tunnel 16, or of another type.

Considerable technical advantages are obtained by the invention.

A first advantage is that the fabric can be placed, in whole or in part, on one or more rigid oscillating platforms, so that the action of relaxation and compaction produced in the mass of the fabric accumulated on the oscillating platform, combined with the action of heating exerted by the drying system, absorbs the residual stresses in the fabric and restores the elastic or plastic deformation.

This is particularly true if we consider that fabric stretch is generally more plastic than elastic.

It is also possible to apply vibrations to the oscillating platform, the frequency and amplitude of which not only simply reduce the friction between the oscillating platform and the fabric and therefore the tension produced by the friction, but also cause an acceleration of the fabric that is a multiple of the acceleration of gravity and therefore a mass force that is a multiple of the weight of the fabric, which facilitates the sliding of the fabrics with respect to each other and achieves a rather compact and stable effect.

Claims (12)

1. A machine for treating a fabric (T), comprising, in combination: -a rigid oscillating platform (2), said rigid oscillating platform (2) being capable of inducing substantially vertical oscillations in a first length of said fabric (T); means (16, 8a, 8b) for drying the second length of fabric; and rollers (5, 6) and a conveyor belt (7) of said fabric cooperating with said drying means, characterized in that

The vibratory platform is in the form of a bucket and the first length of fabric is placed on the vibratory platform,

the rollers (5, 6) and the conveyor belt (7) are arranged for picking up the fabric from the one platform, unwinding the second length of fabric for the action of the drying means and placing the fabric on the one platform.

2. The machine of claim 1, including means for inducing vibrations having a frequency and amplitude such that accelerations that are multiples of gravitational acceleration are applied to the first length of fabric.

3. A machine according to claim 1 or 2, comprising means for causing vibrations having a peak-to-peak amplitude of between 20mm and 60mm and a frequency of between 5Hz and 15 Hz.

4. The machine of claim 3, the vibration having a frequency between 5Hz and 10 Hz.

5. The machine according to claim 1 or 2, wherein the drying means comprise a drying tunnel (16) associated with the oscillating platform (2) so that the fabric to be treated can be alternately transferred from the oscillating platform to the drying tunnel so as to treat the fabric discontinuously.

6. A machine for treating a fabric (T), comprising, in combination: two or more rigid vibration platforms (18, 19, 20), said rigid vibration platforms (18, 19, 20) being capable of inducing substantially vertical vibrations in a first length of said fabric (T); means (16, 8a, 8b) for drying the second length of fabric; and a roller (17) and a conveyor belt of said fabric cooperating with said drying means, characterized in that

The vibratory platform is in the form of a bucket and the first length of fabric is placed on the vibratory platform,

the roller (17) and the conveyor belt are arranged for picking up the fabric from at least one of the two or more platforms, unwinding the second length of fabric for the action of the drying means and placing the fabric on an adjacent platform.

7. The machine of claim 6, including means for inducing vibrations having a frequency and amplitude such that accelerations that are multiples of gravitational acceleration are applied to the first length of fabric.

8. A machine according to claim 6 or 7, comprising means for causing vibrations having a peak-to-peak amplitude of between 20mm and 60mm and a frequency of between 5Hz and 15 Hz.

9. The machine of claim 8, the vibration having a frequency between 5Hz and 10 Hz.

10. The machine of claim 6 or 7, wherein two or more rigid vibrating platforms (18, 19, 20) are provided operatively associated with one or more drying tunnels (16) and positioned with respect to said one or more drying tunnels (16) so that the fabric to be treated is continuously transferred from one vibrating platform to the other through said drying tunnels.

11. A method for treating a fabric, the method comprising in combination the steps of: a step of inducing substantially vertical vibrations in a first length of said fabric; and a step of simultaneously drying a second length of said fabric, characterized in that

The vertical vibration is caused by a rigid platform in the substantially compacted mass of the first length of fabric,

the second length of fabric is dried in an expanded state,

the following steps are also provided: a step of picking up the fabric from the platform, a step of unrolling the second length of fabric for the action of a drying device and a step of placing the fabric on the same or an adjacent platform.

12. The method of claim 11, wherein the frequency and amplitude of the vibration is such that an acceleration that is a multiple of the acceleration of gravity is applied to the fabric.