Textiles: spinning – twisting – and twining – Apparatus and processes – Monitor and control
Patent
1994-10-03
1998-09-08
Stryjewski, William
Textiles: spinning, twisting, and twining
Apparatus and processes
Monitor and control
28248, 28249, 57 93, 57284, 57287, 57289, 57290, D01H 746
Patent
active
058028323
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to the manufacture of yarn by the false twist texturing method in which a multistrand synthetic yarn is given a false twist and heated to "texture" or "bulk" the yarn. Among other advantages "texturing" improves the feel of garments made from the yarn.
Typically a very large machine is needed for texturing yarn. This machine includes numerous similar portions, sometimes as many as 216, in each of which yarn is textured. The portions are known as "positions" and each position has a supply of yarn to be textured, a texturing apparatus and a take-up for the textured yarn. Each texturing apparatus is some six metres high with heating and cooling zones some two to three metres long and subject to varying ambient conditions. All the positions are intended to operate at the same texturing conditions and all are supplied with the same type of yarn. In theory the whole machine will operate at the same conditions and each position will produce yarn which is textured in the same way. However, in such a large machine the conditions will not always be the same from position to position and variations in texturing are inevitable despite careful design and constant attention to operation. In particular the heating arrangement is inflexible and it is appropriate to classify such machines as isothermal, also recognising the aim of an identical heat state at each position. Despite the above developments the need for more economic manufacture demands improvements above the speed and quality now achieved. In particular the dyeability of the yarn can vary due to inconsistency of yarn texturing input and this can lead to the rejection and waste of much material.
In EP-A-20143974 (Teijin Ltd) there are suggestions for an isothermal method of producing textured polyester yarn in which the heater length can be reduced to less than 1.8 metres. Specifically a heater length of 0.65 to 0.70 metres with a yarn speed of 400 metres per minute and a straight line path is proposed. However the method requires a special heater called a "non-touch" type with a bow shaped yarn path in which the yarn is guided by plates with shaped slits to suppress a yarn balloon. The heater temperature is from 300.degree. C. to 800.degree. C. If the yarn breaks in the heater it will be destroyed by the very high temperature of the heater burning off the yarn. The very high temperature is needed as heat is transferred to the yarn by radiation in an open environment so heat loss is high. Because the yarn must not touch the heater the yarn must be "lifted off" during start-up and similar interruptions to continuous running.
In U.S. Pat. No. 4888945 (Murata), and equivalent DE-A-3811437, a quality control technique for a conventional yarn texturing apparatus is described which avoids harm to yarn quality which can be caused by testing yarn during production. The technique is based on measurements made while yarn is being wound onto the empty bobbins when first loaded to replace bobbins doffed with full packages.
EP-A-20271252 (Rieter Scragg) describes a conventional isothermal yarn texturing apparatus to which a monitoring method is applied. This monitoring method involves measuring the difference in crimped yarn velocity when under high tension (velocity V1) and low tension (velocity V2). The quantity V1-V2.times.100 is defined as the crimp velocity and is stated to V1 have a positive relationship to the crimp retraction quantity.
GB-A-841255 (Dunlop) describes an apparatus for determining the change in length under load of a length of filamentary material travelling from one point to another. Lengths of material under zero and known tension are compared in percentage terms to give extensibility of the material.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved yarn texturing production technique.
According to the invention there is provided a method of controlling the manufacture of false twist textured yarn characterised by adjusting non-isothermally in a closed loop
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Stryjewski William
University of Manchester Institute of Science and Technology
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