Textiles: manufacturing – Thread finishing – Surface modification of running length
Patent
1996-10-02
1998-03-17
Crowder, C. D.
Textiles: manufacturing
Thread finishing
Surface modification of running length
2248, 2250, D02G 100
Patent
active
057272930
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to the field of textile technology and concerns a method and an apparatus for continuous crimping of threads made from a thermoplastic material.
BACKGROUND AND SUMMARY OF THE INVENTION
For continuous crimping of threads (bundles of fibrils) of thermoplastic material these threads are conveyed through a duct e.g. by means of a hot transporting medium flowing under pressure in which process the threads are heated and then are transferred into a stuffer box designed in such a manner that the pressure of the transporting medium is released as the transporting medium escapes from the nozzle outlet opening. In the stuffer box the thread hits against a plug formed by thread that already had left the opening, in which process it is crimped. The plug is transported further at a speed lower than the thread speed in the conveyer duct, subsequently is cooled down and opened up to yield the texturized yarn.
The stuffer box in which the plug is formed can be limited by stationary perforated walls, formed e.g. by slats, which longitudinally surround the plug along its length. The plug is pushed by the pressure of the transporting medium to overcome the friction forces on the stuffer box walls throughout the stuffer box which it leaves via a plug opening arranged opposite the outlet opening which can be provided with a pair of delivery rolls which expels the plug in a controlled manner.
The stuffer box also can be limited partially only by stationary walls, and partially by walls which move at plug movement speed. A method and an apparatus for continuous crimping of thermoplastic threads using a stuffer box provided with walls, part of which move with the plug, are described e.g. in the European Patent Nr. 310890 applied for by the same applicant. The apparatus described comprises a texturing nozzle with a conveyer duct, an outlet opening and two shaped extension members extending therefrom in the direction of thread transport. For transporting the plug formed between the shaped extension members a duct formed by lateral guide means and extending along the circumference of a rotating plug transporting roll is provided into which the shaped extension members extend. The lateral guide means of this duct constitute the elements of the stuffer box wall moving with the plug. The plug moves from the stuffer box between the lateral guide means along part of the circumference of the plug transporting roll and then is transferred to another transporting element where it is cooled down and subsequently is opened up into a texturized yarn.
The thread is transported by means of a transporting medium through the conveyer duct and through the outlet opening into the stuffer box. Immediately beyond the outlet opening the pressure of the transporting medium is released. The thread hits the plug forming and is crimped in the process. Formation of the plug upon insertion of the thread at the start of production is initiated under the influence of a braking or stemming force acting temporarily, e.g. of an air stream directed against the thread. During operation an equilibrium is maintained between the compressing pressure of the transporting medium pushing the plug and the friction forces on the walls braking the plug, continuous plug formation and a constant plug movement speed being established and maintained.
The quality of the texturized yarn is closely related to the uniformity of the crimping process i.e. to the uniformity of plug formation. In the absence of a plug the thread is not crimped at all. If plug formation sets in at a distance too far from the outlet opening the plug density is reduced in such a manner that crimp no longer is sufficiently intense nor sufficiently permanent. This signifies that for high thread quality the position, consistency, and speed of movement, of the plug are to be maintained as constant as possible.
In all apparatuses known thus far for continuous crimping of threads of thermoplastic material using a texturing nozzle and a stuffer box irregula
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Crowder C. D.
Maschinenfabrik Rieter AG
Worrell Jr. Larry D.
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