Textiles: ironing or smoothing – Smoothing machines – Roller presser
Reexamination Certificate
1999-04-16
2002-05-07
Izaguirre, Ismael (Department: 3765)
Textiles: ironing or smoothing
Smoothing machines
Roller presser
Reexamination Certificate
active
06381883
ABSTRACT:
TECHNICAL FIELD
This invention relates to a method, and apparatus for performing the method, for the continuous pressure decatising of fabrics. The invention also extends to a method and apparatus for continuously setting staple fibers, wherein the staple fibers are contained in an assembly of fibers such as a sliver, roving, strand, yarn or the like. The invention is particularly suitable for setting wool fibre assemblies and decatising woollen and wool containing fabrics (hereinafter the term wool fabric or the like is to be understood as encompassing fabrics containing a mixture of wool and another or other fibers) and will be described hereinafter with reference to such fibers and fabrics, but it is to be understood that the invention is applicable to other staple fibers, and to other fabrics such as, for example, cottons and rayons which are generally decatised to set the material, enhance lustre or impart some dimensional stability.
BACKGROUND
Pressure decatising is a finishing treatment whereby a wool fabric's physical and dimensional form is enhanced and then stabilised by the use of heat, moisture, pressure and time. Generally, a pressure decatising method produces a permanent change in fabric properties by the action of heat and pressurised steam at greater than 100 kPa (1 atm) pressure on a mechanically constrained fabric, and is usually performed during the final stages of fabric production for several reasons:
(a) to develop desirable aesthetic qualities in the fabric such as handle, lustre and smoothness,
(b) to improve the dimensional stability of the fabric particularly for purposes of garment assembly, and
(c) to permanently set or preserve these qualities during fabric use. A continuous pressure decatising method imparts a permanent finish to a fabric in two distinct operations, fabric relaxation/setting followed by fabric stabilisation, For fabric relaxation/setting, the fabric is for example subjected to mechanical compression in an ambient of steam at high pressure and temperature, which allows the fibers to relax and adopt a new conformation. For fabric stabilisation, the fabric undergoes cooling and drying processes which set the fabric in its new conformation and also bring it back to room ambient. Similarly, individual fibers in an assembly of staple fibers can be treated by heat and pressurised steam whilst mechanically constrained, and then be cooled and dried to set them.
One known type of continuous decatising apparatus comprises a perforated heated drum having an endless belt held in tension and wrapped around most of the circumference of the drum. The fabric, which it conveyed between the surface of the drum and the belt as the drum rotates, is thus pressed between the drum and the belt surface. Besides being heated by the drum, the fabric is also subjected to steam which is introduced through the drum perforations. Alternatively a laminar-shaped enclosure may be formed between an impermeable pressure belt and an unperforated drum. Pressurised steam is generated in this enclosure by vaporisation of moisture carried in by the belt-fabric sandwich. The “Super finish-GFP” machine made by Menschner (now MTECH) provides an example of this latter apparatus.
The pressure belt in this known type of apparatus simultaneously compresses and seals the fabric against the rotating drum. However the level of permanent set that can be imparted to the fabric is limited by the tensile strength of the pressure belt because it is the tension in this belt that provides the seal to maintain a saturated atmosphere within the fabric to set the fibers. Furthermore, the belts in this apparatus wear quickly and require frequent periodic and thus costly maintenance because of their continuously high tensile stress and high temperature working conditions. A further problem with this apparatus arises from the dual role of the pressure belt, that is, it must simultaneously form a high pressure seal with the drum and also apply mechanical pressure to the fabric. To make a leak-tight seal with the drum, the sealing pressure exerted by the belt must exceed the pressure of the enclosed steam, but the mechanical pressure actually applied to the fabric will be reduced by the “cushioning” effect of this steam. Consequently it is difficult to control the fabric compression as it will depend on the steam pressure within the enclosure.
Another known type of continuous pressure decatising apparatus, of which the “Ekofast” machine developed by WIRA (Wool Industries Research Association) and Mather & Platt provides an example, involves transporting the fabric between two end less belt conveyors through an autoclave containing saturated steam. At least one of the conveyors is permeable and the fabric is subjected to impulsive compression by nip rollers. The belt conveyors in this apparatus are tensioned to maintain a desirable fabric finish. Although this tensioning is not as high as in the first described known apparatus, the belts have to be permeable and belt wear is still a problem. This apparatus can impart a reasonable permanent finish to wool fabric, however the required treatment time is much longer than that in the first described known apparatus.
Generally, known continuous pressure decatising apparatus require complex sealing arrangements due to the need to seal an enclosure of saturated steam at high pressure and yet allow a fabric to enter the enclosure, flat set and emerge from the apparatus in a continuous fashion. Example disclosures which deal With this sealing problem for continuous decasting apparatus are provided by European Patent 0533295 and International Application No. PCT/IT92/00114 (WO94/10367). A further problem is the need to ensure adequate insulation of the enclosures of saturated steam.
In summary, known continuous pressure decatising methods and apparatus involve problems with belt wear, the sealing of enclosures for saturated steam and insulating those enclosures. The solutions to these problems offered to date tend to be complex and thus costly. Furthermore, it has been difficult to date to closely control and readily adjust the steaming conditions, namely the temperature of the saturated or superheated steam to which a fabric is subjected during a continuous decatising method.
DISCLOSURE OF THE INVENTION
The present invention is based on the realisation that the steaming conditions in a continuous pressure decatising method may be controlled using a surrounding pressurised atmosphere, preferably of air and preferably at ambient temperature, and controlling the pressure of that atmosphere, and that such a surrounding atmosphere could also reduce the belt wear, sealing and insulation problems of the prior art. It wag also realised that this principle of using an enclosing compressed gas for controlling steaming conditions could be applied more generally for the setting of staple textile fibers as such.
Accordingly, in a first aspect of the present invention, there is provided a method for continuously pressure decatising a fabric including the steps of
(i) establishing a region of compressed gas having a pre-determined pressure,
(ii) continually conveying a fabric through the region of compressed gas by and between two conveying members,
(iii) applying saturated or Superheated steam at a high temperature to the fabric within the region of compressed gas and simultaneously pressing the fabric between the two conveying members,
wherein the high temperature of the saturated or superheated steam is determined substantially by the predetermined pressure of the region of compressed gas.
In a second aspect, the invention provides a method for setting staple fibers wherein the fibers are contained in an assembly of fibers such as a sliver, roving, strand, yarn or the like, the method including the steps of
(i) establishing a region of compressed gas having a predetermined pressure,
(ii) continually conveying the assembly of fibers through the region of compressed gas,
(iii) applying saturated or superheated steam at a high temperature to the assembly of fibers
Chudleigh Peter William
Le Cuong Viet
Ly Nhan Gia
Phillips David Graham
Tester David Henry
Izaguirre Ismael
The Commonwealth of Australia Commonwealth Scientific and Indust
LandOfFree
Continuous pressure decatising of fabrics and setting of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Continuous pressure decatising of fabrics and setting of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Continuous pressure decatising of fabrics and setting of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2883643