Method and apparatus for imparting false twist to yarn before ring spinning

Active Publication Date: 2013-10-03
THE HONG KONG POLYTECHNIC UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Benefits of technology

[0014]This invention provides a method and apparatus which is effective and efficient in operational use, which reduces the

Problems solved by technology

However, it has been found that this single-belt technology results in an increase in yarn defects above the usual level—including the number of thick places, thin places and neps.
A sharp increase in the number of neps is of particular concern, since neps can be a cause of ends down in downstrea

Method used

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  • Method and apparatus for imparting false twist to yarn before ring spinning
  • Method and apparatus for imparting false twist to yarn before ring spinning
  • Method and apparatus for imparting false twist to yarn before ring spinning

Examples

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Example

[0023]In the first embodiment of FIG. 1, the fibre bundle exits from the nip 27 between the front rollers 14a, 14b and extends to the point to which the twist is propagated from the belts 15, 16 (forming the so-called spinning triangle). Then yarn 13 passes through the fixed pigtail or yarn guide 23 then wraps about a first convex surface of the upper run 15a, then passes between the upper and lower runs, before wrapping about a second convex surface of the lower run 16a. The belts 15, 16 may be alike, having a circular cross section of the same diameter, such that the convex surfaces have the same radius of curvature. As shown in FIG. 2, the first convex surface is subtended at the central axis of the upper run 15a by an angle of wrap 28a. The second convex surface is subtended at the central axis of the lower run 16a by an angle of wrap 28b. The angles of wrap 28a, 28b may vary between the upper and lower runs 15a, 16a and for the geometry shown, where the upper and lower runs 15a...

Example

[0026]As shown in FIG. 5, in the second embodiment the upper and lower linear runs 15a, 16a may alternatively engage on the same side of the yarn 13, in which case they are driven in the same direction to impart the false twist in a common direction. As in the first embodiment, the belts 15, 16 may be alike, having a circular cross section of the same diameter, such that the convex surfaces have the same radius of curvature. Alternatively, the belts may have convex surfaces having different radius of curvature which are in contact with the yarn. The first convex surface is subtended at the central axis of the upper run 15a by an angle of wrap (of approximately 5°) which is smaller than the angle of wrap subtended by the second convex surface at the central axis of the lower run 16a (which may be of approximately 20). The yarn 13 may be deflected from the angle of 45° to the horizontal of the drafting system 12, having a larger angle of wrap about front roller 14b than about front ro...

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Abstract

A method and apparatus for imparting false twist to a short staple yarn delivered from a nip of a pair of front drafting rollers before ring spinning. Downstream of the nip, the twisted yarn is drawn sequentially across first and second runs of travelling endless belts, such that the yarn wraps about a first convex surface of the first run, then passes between the first and second runs, before wrapping about a second convex surface of the second run. Friction between each of the first and second convex surfaces and the yarn imparts the false twist in a common direction. Maintaining a differential between first and second linear speeds of the first and second runs, respectively, has been found to reduce yarn defects, particularly the nep count.

Description

TECHNICAL FIELD [0001]The present invention relates to yarn manufacture by ring spinning, and more particularly to a method and apparatus for imparting false twist to a yarn delivered from a nip of a pair of front drafting rollers immediately before imparting real twist by ring spinning.BACKGROUND OF THE INVENTION[0002]The characteristics of ring spun yarn are unmatched by the products of other yarn spinning techniques which may be more productive, so it is a technology that is unlikely to be superseded in the near term. Much research has gone into ring spinning technology and relatively modest improvements to the productivity of a ring spinning frame can be very significant in a spinning mill where many thousands of spindles are employed. Many different raw material and machine-related factors directly influence both productivity and quality, and sometimes improvements in one area have consequences that necessitate a trade-off in another area. The goal of spinning technologists mig...

Claims

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Application Information

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IPC IPC(8): D01H7/92
CPCD01H7/92D01H1/02D01H7/926
Inventor TAO, XIAO MINGXU, BIN GANGHUA, TAOFENG, JIEGUO, HENGJIA, YUNHUI
Owner THE HONG KONG POLYTECHNIC UNIV
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