EP0003684B1

EP0003684B1 - Radio-frequency textile drying method and apparatus

Info

Publication number: EP0003684B1
Application number: EP19790300204
Authority: EP
Inventors: Geoffrey Allan Smith; Thomas Fraser Mcaulay
Original assignee: Dawson International PLC
Current assignee: Dawson International PLC
Priority date: 1978-02-13
Filing date: 1979-02-09
Publication date: 1983-05-18
Also published as: GB1567111A; DE2965417D1; ES8101152A1; EP0003684A1; ES478089A0

Description

This invention relates to a method and apparatus for drying textile material by exposure to radio-frequency energy and which can also be used for causing dye fixation simultaneously with drying.
In French Patent Specification 2299443 there has been proposed apparatus for the drying and heat treatment of hanks or bobbins of textile threads which comprises a continuously drivable transporter on which hollow supports for the hanks or bobbins are mounted, and at least one pair of electrodes disposed on either side of the path of the hanks or bobbins and connected to a high frequency generator. The hollow supports are rotatably mounted on the transporter and means are provided for rotating the supports. A housing is disposed under the transporter and connected to fluid circulation means for example a vacuum source. In that specification there is specifically described an embodiment of such apparatus wherein the transporter comprises a rotating plate and the electrodes are cylindrical and coaxial with the rotation axis of the plate. The vacuum source applies a reduced pressure within the hollow supports which are perforated, and surmounted by a sealing belt and moisture in the form of vapour is removed from the hanks or bobbins through the hollow supports. The preferred radio frequency to be applied to the electrodes and the intended duration of operation of the described apparatus to achieve adequate drying and heating is not however specified yet is vitally important for effective operation and for the avoidance of damage to the treated textile material.
The object of the present invention is to provide a more effective and reliable method of treatment by use of apparatus which is simplified and different in construction and operation compared with that of the prior art and does not require sealing means.
In accordance with the invention a method of drying textile material comprises mounting the material on upright supports which are spaced around a substantially horizontal turntable between plates for creating a radio-frequency energy field in the vicinity of said supports, and thereafter rotating the turntable, whilst exposing the material on the supports to radio frequency energy and evacuating water vapour from the material by application of vacuum thereto characterised in that said material is simultaneously exposed to vacuum and radio frequency energy, that suction is applied to the exterior of the textile material by creating reduced pressure in a casing which encloses the plates and supports on the turntable and that first water and then water vapour driven from the material is evacuated from the casing by a vacuum pump during a treatment period of between 5 and 15 minutes at a radio frequency of 27.12 MHZ.
Further apparatus for the performance of such method comprises a substantially horizontal turntable having upright supports spaced around its periphery for supporting yarn packages, means for rotating the turntable about its vertical centre axis, and means for creating a radio frequency energy field in the vicinity of the thus supported packages while the turntable rotates. The apparatus according to the invention is characterised by a casing which encloses the supports on the turntable and the said means and by a vacuum pump having at least one inlet reaching to the bottom of the casing for successively evacuating water and water vapour from the casing and the packages on the supports, under the combined effect of vacuum and radio frequency energy simultaneously applied externally to material on the supports during a treatment period of between 5 and 15 minutes at a radio frequency of 27.12 MHZ.
A preferred embodiment of the apparatus according to the invention, and which is designated a radio frequency drying, relaxation and setting unit, is illustrated in the accompanying drawings to which reference is hereafter made. In these drawings:-

Fig. 1 is a front elevation of the unit;
Fig. 2 is a side elevation of the unit;
Fig. 3 is a plan view of the unit; and
Fig. 4 is a perspective view of the unit.

Referring now to the drawings, the unit comprises a casing 1 of rectangular shape formed on four sides with access openings covered by removable panels 2. The casing 1 has a superstructure 3, also of rectangular shape, with access openings on two opposite sides covered by removable panels 4. The superstructure 3 contains for example a 45 KW. 27.12 MHz dielectric generator (not shown).
The casing 1 mainly contains a rotary motor- driven turntable 5 which carries, around its periphery, a plurality of vertical electrically insulated locating spindles 6 for receiving packages-e.g. cones, cheeses or muffs-of yarn. The casing has a rectangular opening 7 in its front side through which an operator can place and withdraw packages on and from the spindles 6. A rotary turntable with 24 spindles 6 is shown and this can be driven by its motor at an infinitely variable speed to enable the unit to handle between 50 and 500 packages per hour as may be required for a particular treatment and type of textile material or fibre. To one side of the opening 7 is a control panel 8 which incorporates all the Radio frequency generator and turntable operating controls (not shown). Two exhaust pipes 11 emerge from the top of the casing 1 and are connected to a vacuum pump (not shown).
As shown in Figs. 2 and 3 there is disposed concentrically within the turntable 5 a stationary 'live' cylindrical electrode 9 coupled to the radio frequency generator, whilst concentrically outside the turntable 5 there is disposed a stationary 'earth' cylindrical electrode 10.
The size and spacing of the electrodes 9 and 10 and the size of the turntable 5 may need to be changed depending upon the textile material which is to be treated and whether drying is or is not required to cause dyesetting and the apparatus is adapted to enable this to be done. In Fig. 2 there are shown alternative positions 9' and 10' for the inner and outer concentric cylindrical electrodes respectively when the unit is to be used for dye-setting and drying, a larger diameter turntable 5' being then also necessary.
The packages placed on the spindles 6 may contain for example up to 5 kilograms of yarn sliver or tow and may carry at least their own weight of water (5 kgs).
The method of treatment after the packages have been placed and the turntable starts to rotate is for the vacuum pump and the radio frequency generator to be simultaneously operated. This first removes liquid water mechanically and then removes water vapour which is driven from the yarn by the radio frequency field within a period of 5 to 15 minutes depending upon the size of the packages. Yarn may be dried to ambient Regain consistent with normal conditioning i.e. 15% for wool, 4% for nylon and acrylic and 1% for polyester. Without the radio frequency energy the vacuum pump will remove very little water.
The method is effective because as the water in the textile material is heated by the radio frequency energy, a positive pressure is produced within the fibre and this expels mechanically retained liquid water as a first step, followed by water vapour as the temperature within each package rises towards 100°C. The liquid water temperature is between 15°C and 30°C and the vacuum pump only ensures that the water which is driven off is removed to a suitable container or drain.
This method can equally well be applied to fibres in most forms provided they are restrained from moving with the air or vapour flow. As examples may be quoted beams (rolls) cloth or beams of yarn as well as packages and loose stock.

Claims

1. A method of causing dye fixation and drying of textile material which comprises mounting the material on upright supports (6) which are spaced around a substantially horizontal turntable (5) between plates (9, 10) for creating a radio-frequency energy field in the vicinity of said supports, and thereafter rotating the turntable, whilst exposing the material on the supports to radio frequency energy and evacuating water vapour from the material by application of vacuum thereto characterised in that said material is simultaneously exposed to vacuum and radio frequency energy, that suction is applied to the exterior of the textile material by creating reduced pressure in a casing (1) which encloses the plates (9, 10) and supports (6) on the turntable (5) and that first water and then water vapour driven from the material is evacuated from the casing (1) by a vacuum pump during a treatment period of between 5 and 15 minutes at a radio frequency of 27.12 MHZ.

2. Apparatus for performing the method of Claim 1, comprising a substantially horizontal turntable (5) having upright supports (6) spaced around its periphery for supporting yarn packages, means for rotating the turntable about its vertical centre axis, and means (9, 10) for creating a radio frequency energy field in the vicinity of the thus supported packages while the turntable rotates, characterised by a casing (1) which encloses the supports (6) on the turntable (5) and the said means (9, 10) and a vacuum pump having at least one inlet (11) reaching to the bottom of the casing (1) for creating a vacuum in the casing (1) and successively evacuating from the casing (1), water and water vapour which has been successively released from the packages supported on the supports (6) as a result of the combined effect of vacuum and radio frequency energy simultaneously applied externally to material on the supports (6) during a treatment period of between 5 and 15 minutes at a radio frequency of 27.12 MHZ.

3. Apparatus as set forth in Claim 2 characterised in that the radio frequency energy field creating means comprises a pair of concentric, cylindrical, vertically disposed electrode plates (9, 10) between which the material is passed whilst revolving with the turntable (5).