The Five Part Analyzes The Causes Of Coarse Yarn.

Coarse pitch is one of the important factors affecting yarn quality. In the post processing process, the efficiency of the winder will not only be reduced, but also the weaving efficiency of the loom will be affected, and even the appearance of the fabric will be affected. Then, what are the causes of coarse yarn?

One

There are more neps and short lint in raw materials or semi products.

Short lint not only affects yarn evenness and strength, but also affects the NEP and coarse section of yarn. For example, after the raw material has been processed by the combing process, because of the removal of about 40% to 60% of the neps and short fibers from the sliver, the yarn is not only good and strong, but also greatly reduces the number of knots and neps. There are many reasons for the short staple content: (1) when the cotton is mixed, there are more short fibers in the raw material, especially the short fibers less than 12 mm. For example, a porcupine opener uses a rectangular blade beater and has a strong effect on fiber when the speed is high. It is easy to produce short fiber when processing raw materials with poor maturity or fineness. In drafting process, the drafting mechanism causes short distance deviation to the short fiber movement control, and the shorter the fiber is, the larger the offset will be. In this way, the fibers will be transferred longitudinally and classified according to their length in the drafting process. The accumulation of short staple is easy to form a coarse joint, and it can also become a coarse section of flying flowers. The offset of the offset will also lead to unevenness of the additional draft, resulting in drafting waves and deteriorating the evenness. The NEP impurity not only disturb the normal movement of other fibers during the drafting process, but also aggregates fibers, forming coarse joints, and destroys evenness.

Two

The carding machine is not well combed, the card clothing is dull, and the short staple is increased.

Especially when spinning polyester / cotton, polyester / viscose, cotton / polyester blended yarns, because chemical fibers are cut into staple fibers, they will produce silk and fiber bundles. If the carding can not be completely loosened, it will move in the spinning process, and finally appear coarse yarn in the yarn. The reasons for insufficient carding are: (1) the quality of the card clothing is poor, the needle face is not sharp enough, the state is bad, the needle is not timely, and the grinding accuracy is not enough; secondly, the distance between the main spacer points is large or inaccurate; thirdly, the uniformity of the cotton web is uneven; the cotton roller and the cotton plate are poorly held on the cotton layer; after the cotton bundles that have not been broken apart after the puncture and carding are transferred to the cylinder cover, the carding load between the cylinder sheets increases, resulting in poor carding. The damaged fibers of carding mainly occur at the feeding board and the roller. Cotton blocks or fiber bundles have poor parallel parallelism, eccentric roller, low fiber maturity, thick cotton feeding layer, small gap between the cotton plate and the stab roller, and the small length of the carding process of the cotton board, which are easy to damage the fibers and increase the short staple content of the sliver. In addition, the small inlet gap and the low speed of the cover are the main reasons for the impurities in the short and the neps.

Three

The coarse section is mainly produced on the spinning frame.

Only a small part of the coarse section is formed in the pre spinning process. The main cause of the coarse yarn in the spinning process is the defective roving joint, the roving inclusion of flying yarn or floral yarn. The position is: (1) when the roving is fed into the spinning frame drafting mechanism, it will bring in the roving roving (about 10% to 15%); (2) in the drafting part, due to the poor drafting process, the rollers are not allowed to pressurize, the cots are cracked, the fibers are three, the collectors are not functioning well, the apron movement is dull, the cleaning work is poor and the reasons are (30% to 50%); (3) the qualified rate of the Spinning Apron joints is low, and the suction force of the broken cotton suction device is insufficient, resulting in the loose yarn attached to the yarns after the broken ends (about 15% to 25%). Coarse section on ring spinning frame In addition, the workshop air supply system is unreasonable, will also cause the workshop air turbulence, flying more, thus easy to generate thick knots.

Four

Unreasonable configuration of spinning process

For example, roving twist factor, roving yarn quantity and spinning machine rear area drafting process mismatch and apron tension, rubber ring jaw gap configuration is unreasonable and so on will produce thick section. When spinning low count carded yarn, the drafting ratio of spinning frame is easy to cause more thick sections. This is due to the quantitative weight of coarse yarn roving. The yarn movement is intense after the yarn enters the front drafting area. The movement speed of the upper and lower aprons varies greatly, the rubber ring rigidity is uneven and the yarn uneven fluctuation is large, and the coarse yarn is easy to generate.

Five

Influence of winding process

As the winding speed increased and the winding tension increased, the CV value of the sliver deteriorated, and the thickness and neps increased. This is because the winding speed is high, the yarn is subjected to the sharp friction of the guide yarn, the tension device and the groove barrel. The increase of winding tension will also cause the friction between the yarn and the winding part, and the surface hairiness will increase. A part of the fibers involved in the yarn will also expose the yarn body, or make the short pile accumulation into a thick section, or make the section of the yarn body increase to form a thick section.