In spinning production,
What are some of the factors that contribute to rough joints?
Raw materials, semi-products in the nep, impurities and short nap content
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Short down not only affects the yarn yarn dryness, strength and hairiness, but also directly leads to a large increase in yarn neps and rough knots. Reasons for the high content of short hair:
(1) The raw materials in cotton blending contain more short fleece below 12mm;
(2) in the process of flower cleaning, opening, striking, carding excessive, produce a large number of short velvet but discharged less.
Excessive carding of cotton causes an increase in short fleece and rough knots
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Especially when spinning polyester/cotton, polyester/viscose, pure cotton and blended yarn, because the chemical fiber will produce and silk, fiber bundle, etc., when cutting into staple fiber, if not all loose when carding, the cluster will move in the spinning process, and the coarse section appears in the final spinning. Combing degree is not enough because:
(1) the selection of needle cloth quality is poor; The cutting edge of the needle cloth is not enough, the condition is poor, the needle reading is not timely, the precision of the needle grinding is not enough;
(2) The separation data in the main carding area is inaccurate or large;
(3) the cotton roll or feasting cotton is uneven in longitudinal direction, the feeding roller and the feeding board hold the cotton layer badly, and the decomposed fiber bundles after carding by the burr roller are mostly transferred to the cylinder cover plate. The cylinder cover plate has a large carding load, resulting in bad carding;
(4) Small leakage bottom spacing is small; The low speed of movable cover plate is also the main reason for the short pile and high content of nep impurities in sliver.
Big rough section is the main production process
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Part of the big rough section is caused in the forespinning process, mainly due to improper setting of bar spacing and insufficient holding force. Improper setting of roving draft spacer, insufficient holding force, bad joint of roving and roving, defects of roving caught in flying or gathering. The parts of the spinning frame causing rough joints are:
(1) When the roving is fed into the spinning drafting mechanism, the product is carried by the roving (about 10%-15%);
(2) In the drafting part due to poor drafting process, inaccurate shaking pressure, poor stability rate; Cots crack, cots around three, bad effect of collector, apron operation, cleaning work not according to the cycle or poor quality (about 30%-50%);
(3) the qualified rate of the yarn stopper joint is low, and the air suction of the broken cotton suction device is insufficient, which leads to the scattering of yarn strands attached to the yarn after the broken yarn (about 15%-25%);
(4) Wire ring scraping yarn or winding into yarn (about 1%-3%); In addition, the workshop air supply system is unreasonable, resulting in workshop air disorder, flying, resulting in short and thick section.
Spinning process configuration is not reasonable
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(1) Unreasonable coordination between roving twist coefficient and quantitative ratio and draft multiple after spinning;
(2) The tension of the apron and the distance between the jaw of the apron are ignored, resulting in rough joints;
(3) When spinning medium and low count yarn, high drafting ratio of spinning yarn is easy to cause more rough knots; It is mainly because of the large quantity of roving yarn, the poor stability of fiber movement after the yarn enters the front draft area, the large difference of synchronicity between upper and lower rubber rings, and the high uneven rate of rubber ring operation and yarn.
The influence of winding on rough joints
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With the increase of winding speed and yarn tension, CV value of strips will deteriorate, coarse details and nep will increase.
(1) With the increase of winding speed, the yarn is subjected to the gathering friction force of yarn guide, tension controller and cylinder.
(2) The increase of winding tension will also cause sharp friction between the yarn and the winding part, resulting in an increase in surface hairiness. Part of the hairiness involved in the yarn body will also expose the yarn body, or the short pile will gather to cause coarse or nep, and the section of part of the yarn body will increase and form coarse knots.
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