Textiles: spinning – twisting – and twining – Apparatus and processes – Untwisting
Reexamination Certificate
1999-04-22
2001-03-27
Calvert, John J. (Department: 3765)
Textiles: spinning, twisting, and twining
Apparatus and processes
Untwisting
C057S002300, C057S315000
Reexamination Certificate
active
06205758
ABSTRACT:
THIS INVENTION relates broadly to the testing of textile fibres, more specifically to a method of and an apparatus for preparing textile fibres for testing.
When a length of textile yarn is formed, its constituent textile fibres are twisted or twined together to cause the fibres frictionally to grip together to form the length of yarn.
In accordance with a first aspect of this invention, broadly, there is provided a method of obtaining fibres from a yarn for testing, including mechanically untwisting the yarn, mechanically separating fibres which have formed the yarn, and gathering said fibres.
It is sometimes required to examine or test the constituent fibres of a length of yarn after the fibres have been twined into the length of yarn or even after a textile article has been produced of the yarn. Such tests or examinations are sometimes directed at determining fibre properties such as length, length distribution, strength, elongation, stiffness, bulk, diameter, fibre linear density, micronaire or fibre fineness in the case of cotton fibres, maturity in the case of cotton fibres, total impurities or contamination in the fibres and the like. To achieve this, it is required to dismantle the yarn into its constituent fibres since these tests or examinations are best or can sometimes only be conducted on the fibres when in a dismantled condition. Such tests and examinations are normally conducted on staple fibres such as cotton, polyester, viscose, nylon, acrylic, modacrylic, polypropylene, wool and other synthetic or natural fibres, or blends of such fibres.
This invention thus provides a method whereby a length of yarn can be dismantled into its constituent fibres in a mechanical fashion, i.e. a non-manual fashion, thus making it feasible to obtain fibres for testing on a commercial basis or scale.
The method may include the prior step of establishing the lay, S or Z, of the yarn and determining the appropriate direction for untwisting the yarn. Untwisting the yarn may be to a degree of 100%+30%. Thus, for example, if the mean twist of the yarn is, say 900 turns per metre, the degree of untwisting may be between about 600 turns per metre (100%−30% approximately) and about 1200 turns per metre (100%+30% approximately). It is to be appreciated that untwisting is to be to a degree to relieve the frictional gripping amongst fibres sufficiently to allow the fibres to be separated by drafting. The Applicant envisages that the optimum degree of untwisting may vary from one kind of fibre and from one kind of yarn construction to another and that routine experimentation may be required to establish an optimum degree or range of untwisting for particular circumstances.
For purposes of this specification, the term “untwisting” is to be understood functionally, i.e. untwisting to a degree which is appropriate for the intended purpose.
The method may preferably include drafting said untwisted yarn to break remaining bonding or adhesion between the fibres.
The method may include unwinding the yarn from a reel, untwisting the yarn then being simultaneous with unwinding of the yarn from the reel. Untwisting the yarn may be by rotating an arm about the reel and guiding the yarn through an eye at an end of the arm. Instead, untwisting the yarn may be by rotating the reel about a polar axis of the reel while unwinding is effected by spinning the reel about an unwinding axis of the reel. The polar axis may be normal to the unwinding axis.
A rate of untwisting the yarn may be responsive to a rate of unwinding the yarn such that the rate of untwisting relative to the rate of unwinding is appropriate for the desired degree of untwisting.
When the method includes drafting the untwisted yarn to break remaining bonding or adhesion between the fibres, drafting may at least partially be between two pairs of nip rollers operating in series, a downstream pair of the nip rollers having a peripheral speed faster than a peripheral speed of an upstream pair of the nip rollers.
The degree of drafting may vary from one application to another. Generally, the Applicant believes that the higher the degree of drafting the better, but naturally there are physical and practical limitations to the degree of drafting which can be obtained. As a rough guideline, drafting may be of the order of about 200%. Routine experimentation may be required to establish an appropriate degree of drafting for particular circumstances.
For purposes of this specification, the term “drafting” must be understood functionally, i.e. drafting to a sufficient degree to break the adhesion between the fibres.
Drafting may include guiding the untwisted yarn between surfaces moving in the direction of drafting and pressing the fibres together to form a bundle of loose or drafted fibres. The surfaces may be provided by opposing surfaces of a pair of opposing, rotating, endless belts.
Separating and gathering the fibres may be by transporting them by means of air movement into a foraminous container. Said air movement may advantageously be obtained by suction.
Separating and gathering may, instead or in addition, include raking the fibres while part of the untwisted yarn, or while part of the bundle of loose or drafted fibres.
The method may include loosely winding the fibres around a drum or wheel provided for this purpose to gather the fibres. The drum or wheel may be hollow, a periphery of the drum or wheel being foraminous, the method including applying suction to suck the fibres onto the foraminous periphery. The method may then include removing the fibres loosely wound around the drum or wheel in the form of a sliver having a length commensurate with the periphery of the drum or wheel.
By way of development, the method may include subjecting the fibres to steam prior to removal.
In accordance with a second aspect of this invention, there is provided a yarn dismantling apparatus including
mechanical untwisting means operable to untwist yarn formed by fibres; and
separating and gathering means for separating and gathering the fibres.
The apparatus may include a spindle for rotatably supporting a reel holding the yarn to be dismantled about an unwinding axis.
The mechanical untwisting means may include an arm having an eye at an end thereof, the arm being rotatable in a selected direction to cause the eye to orbit the reel in the selected direction.
An inner end of the arm may be mounted on a bush or bearing rotatable about the spindle or a journal coaxial with the spindle, the apparatus including drive means for rotating the arm in said selected direction and at a selected speed by transmitting drive via the bush or bearing to the arm.
Instead, the untwisting means may include means for rotating the reel about a polar axis thereof. The polar axis may be normal to the unwinding axis.
The apparatus may include unwinding means for unwinding the yarn at a selected rate from the reel, the unwinding means including a pair of unwinding nip rollers downstream of the spindle, the unwinding nip rollers being rotatable such that a tangential speed thereof corresponds with the selected rate of unwinding.
The apparatus may include a pair of intermediate nip rollers downstream of the unwinding nip rollers. The intermediate nip rollers may be rotated such that a tangential speed thereof is only very slightly faster than that of the unwinding rollers to prevent slack in the length of untwisted yarn.
Preferably, the apparatus may include drafting means for drafting said untwisted yarn to break remaining bonding among respective fibres, the drafting means including a pair of driven drafting nip rollers downstream of the unwinding nip rollers, and downstream of any intermediate nip rollers. A spacing between the drafting nip rollers and nip rollers upstream thereof may advantageously be at least more than the longest fibre length in the yarn being dismantled. The apparatus may include drive means drivingly connected to the drafting nip rollers to drive them at a tangential speed faster than that of the unwinding rollers, to cause corresponding draf
Cizek Jaromir
Weideman Etienne
Calvert John J.
Ladas and Parry
Technology Finance Corporation
Welch Gary L.
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