EP0274994A1

EP0274994A1 - Method and apparatus for crimping a fabric on a stretchable support

Info

Publication number: EP0274994A1
Application number: EP87830432A
Authority: EP
Inventors: Pietro Alberto
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-12-15
Filing date: 1987-12-11
Publication date: 1988-07-20
Also published as: JPS63159570A; IT1199761B; JPH0784701B2; IT8622684A0; IT8622684A1

Abstract

A process is described for freely steaming, i.e. under conditions of no mechanical stresses, a fabric (6) on a stretchable support (5). A fabric web is freely and continuously fed at an area where the support is stretched and, while passing through the steaming region, it is subjected to a mechanical thrust due to the support recovery. The contemporary effect of both actions enhances the fabric shrinkage. An apparatus for carrying out this process comprises, as a support, a stretchy web of fabric or mat that is wound, like an endless loop, about at least two rollers of different speed (1,2), between which there is the steaming zone. The roller being upstream of this zone has a peripheral speed greater than the roller downstream thereof, whereby the support is initially stretched and elongated until it releases when leaving the steaming zone.

Description

The present invention relates to a process for the steaming of fabrics on a stretchable support as well as an apparatus for carrying out this process.
It is known that fabrics at a given stage of their manufacture, usually before the finishig step, are subjected to a steam conditioning in order to cause their shrinkage, whereby they acquire the required dimensional stability to avoid possible subsequent deformations, especially undue shrinkages during the fabric use as made-up products, such as articles of clothing. This operation, which is commonly named "steaming" can take place by treating fabric when compressed as a wound roll, through the so-called "decatizing", possibly in autoclave, or by steaming the fabric, free of mechanical stretches or compressions, in order to enhance as much as possible its dimensional stabilization, without being influenced by external conditions. This is typically obtained by depositing the fabric to be treated being fed in excess onto a support formed of a perforated mat or woven material, then blowing steam toward the fabric throughout the support perforations. The overfed fabric is thus free to shrink under the steam action.
The results thus obtained are not however the best that could be expected, as the steam action cannot be evenly the same throughout the whole fabric to be treated, just because of its being fed in excess, whereby some fabric portions are less exposed to this action during the treatment. Furthermore it is deemed that the fabric shows some resistance to the dimensional shrinkage, if the latter is not somehow aided.
It is therefore the object of the present invention to provide a process which ensures better results through an even action of the steam onto the fabric without making use of overfeeding. The fabric, freely fed without stretches or accumulations, is gradually induced to shrink by means of a continuous, smooth mechanical action which, in combination with the steam effect, brings to those desired best results, never obtained so far and remained theoretical.
The process according to the invention is characterized by the steps of freely feeding, without tension, the fabric to be treated on a stretchable support being elongated in the contact area under a pull action, causing said support to be continuously forwarded along a fabric steaming region while at the same time the elastic recovery of the support gradually occurs, whereby the support shrink causes an increasing fabric crimping during the treatment, possibly also in the width, not only in the length direction.
Also according to the present invention an apparatus is additionally provided which carries out the above-mentioned process and comprises an endless web formed of a perforated stretchy support being wound about at least two rollers having different peripheral speeds, with a steam generator capable of liberating steam through the upper path of said endless web, along a portion thereof which is downstream of the roller having the greatest peripheral speed, in the proximity of which the fabric to be treated is freely fed onto said support.
According to a particular aspect of the present invention, the roller that is downstream of said steam generator, having a lower peripheral speed, will be preferably provided with circumferential grooves in order to assist the support in its elastic recovery also in the transverse direction, and therefore the fabric shrink in the width direction.
These and further objections, advantages and features of the process according to the invention will be apparent to those skilled in the art by the following description of an embodiment of the apparatus for carrying out this process, given by way of a non-limiting example with reference to the drawings in which:

FIGURE 1 shows a diagrammatic side elevation view of an apparatus for steam conditioning fabrics according to the invention; and
FIGURE 2 shows a top plan view of the apparatus of Fig. 1.

With reference to the drawings, the process according to the invention provides for using, as a support for continuous steaming a fabric 6, a stretchable material 5 which is wound, as an endless web, about at least two motorized rollers 1, 2. The material of support 5 will be elastic, so as to be able to stretch especially in the longitudinal sense, but preferably in all directions, upon a sufficient mechanical thrust, and to elastically return to the original dimensions. It will be clear that in this case it is not a matter of natural elasticity only shown by whichever material, especially fabrics. As a matter of fact there is meant here a mat formed of e.g. a multiplicity of elastic rubber bands, or a fabric woven by elastic fibres such as those known under the tradename "lycra". It will be appreciated that the stretchable support material should be perforated or anyhow caused to be pervious to the steam issued by an underlying steam generator, of known type, designated 4 in the drawing.
From a feeding cylinder 3 the fabric 6 to be treated is caused to rest on the upper branch of support 5 in the direction of arrow G, free of tensions or mechanical stresses of any type.
According to the invention, roller 1 is driven to rotate at a greater peripheral speed, such as 20-30% higher than the speed of roller 2, each roller being independently driven. Thereby due to the differential speed, the pull exerted by roller 1 will cause the support to be stretched along the lower branch and the same to gradually return to the conditions of normality along its upper branch. Upon leaving the roller 1, at the zone designated 7 where the support contacts fabric 6, the latter is fed by cylinder 3 at the same speed of roller 1 or at most a slightly greater speed, since it is preferred to have a feeding slightly in excess rather than tensions caused by a pull action made by the support 5. While the elastic web of support 5 follows its path to the roller 2 in the direction of arrow F, the tension is released and at the same time the fabric 6 freely deposited thereon will assume a crimped pattern as a consequence of the longitudinal shrink or recovery of the support. Such a crimping effect will occur gradually across the zone in which the fabric is steamed through the support by the steam generator 4. Therefore at the same time the fabric undergoes both a steaming action and an accumulation under the thrust caused by the elastic recovery of support 5, whereby the best conditions exist for a dimensional conditioning treatment of the fabric.
With particular reference to Fig. 2, there is seen that roller 2 is preferably grooved being formed with circumferential grooves 8 which assist the support 5 web in its elastic recovery also in the direction perpendicular to the arrow F direction. Therefore the fabric 6 will be induced to shrink not only in the length, but also in the width direction, with a dimensional conditioning which is as much isotropic as possible.
Although only two rollers have been shown, about which the stretchable support web is wound, they could also be in a number more than two.

Claims

1. A process for the steam conditioning of fabrics on a stretchable support, characterized by the steps of freely feeding, without tension, the fabric to be treated on a stretchable support being elongated under a pull action in the contact area, causing said support to be continuously forwarded along a fabric steaming region, while at the same time the elastic recovery of the support occurs, whereby the support shrink causes an increasing fabric crimping during the steaming treatment.

2. A process according to claim 1, characterized by the fact that the stretchable support is also subject to a stretch action in a transverse direction with subsequent elastic recovery during the steaming of the fabric carried thereon, whereby the fabric is gradually accumulated not only in the longitudinal, but also in the width direction.

3. An apparatus for continuously steam conditioning fabrics, characterized by the fact of comprising an endless web of a stretchable support material (5) which is perforated and wound about at least two rollers (1, 2) having different peripheral speeds, with a steam generator (4) for the emission of steam through the upper path of said support web (5), along a portion thereof which is downstream of said roller (1) having the greatest peripheral speed, in the proximity of which the fabric (6) to be treated is freely fed onto said support web (5).

4. An apparatus according to claim 3, characterized by the fact that the fabric (6) to be treated is fed without stresses to said support (5) from a cylinder (3) having the same speed or a slightly greater speed that said roller (1) to prevent fabric (6) from tensions at an area (7) of contact with said support web (5) immediately following said roller (1) of greater speed which is positioned upstream of said steam generator (4) and other roller (2) in the forward direction of the fabric.

5. An apparatus according to claim 3 or 4, characterized by the fact that said roller (2) being positioned downstream of said steam generator (4) and having a lower peripheral speed is provided with circumferential grooves (8) to help the elastic recovery of the stretchable support web (5) also transversely, not only longitudinally.