It is impossible to completely avoid yarn breakage in rotor spinning production. The yarn breakage will have a certain impact on the output, quality and manufacturing rate of cotton yarn. The higher the breakage rate, the greater the harm. Therefore, the occurrence of breakage should be minimized during production. The following analyzes the causes of yarn breakage in the self-ventilating rotor spinning machine.
01 Process factors
1) Rotor speed
When the whiskers are peeled off and twisted, they will have strong friction with the condensation groove. The higher the rotor speed, the greater the friction resistance, making it difficult to peel off and twist the whiskers. Therefore, when other factors remain unchanged, the higher the speed of the spinning rotor, the more yarn breakage will occur.
2) Yarn-drawing speed
Yarn-drawing speed determines the twist, within a certain range The internal twist is large, the yarn strength is also high, and the yarn breakage is less during the spinning process. When the yarn transitions from whiskers to yarn in the initial stage of twisting, the strong effect of twisting on the yarn is particularly important. Therefore, when other conditions remain unchanged, the faster the yarn drawing speed, the higher the end breakage rate.
3) Cotton
The raw materials used in rotor spinning are mostly low-grade cotton and some recycled Cotton is used. These raw materials contain more impurities and dust, and have a higher short staple rate. The main length of the fiber is short and the strength is low. This increases the difficulty of spinning and also increases the chance of yarn breakage. probability. Therefore, if other conditions remain unchanged, increasing the cotton level can significantly reduce the occurrence of yarn breakage.
02 Working status of spinning device
1) Spinning rotor
The working status of the condensation groove of the spinning rotor plays an important role in the evenness level and end breakage of the yarn. If there are many impurities and small dust clusters in the condensation groove, the condensation tank will enter the condensation groove. The fiber distribution in the groove is uneven, and the strength of the section of whisker with less cotton fiber distribution must be lower when peeled off. Another situation is that the oxide layer in the condensation tank peels off due to excessive use or improper use of the spinning rotor, making it very difficult to peel off the cotton fibers embedded in the condensation tank. Both of the above situations destroy the connection force between the slivers and increase the difficulty of twist formation and transmission. When the strong force of the sliver cannot overcome the frictional resistance of the condensation groove, the yarn will break.
2) Opening roller
The rack of the opening roller should be smooth and sharp, so that it can It is beneficial to the carding, removal and transfer of fibers. However, the opening roller will inevitably produce inverted teeth and curved teeth during the production process. These hooks are very detrimental to the transfer of cotton fibers, and will gather cotton fibers to form cotton bundles. If the cotton bundles enter the spinning rotor with the negative pressure airflow, due to Its mass is relatively large, so its centrifugal force and frictional resistance are also large, which increases the difficulty of peeling and twisting, causing the yarn to break. The broken ends caused by the hooks of the opening roller have a small piece of cotton bundle at the end of the yarn.
3) Anti-twist disc
Anti-twist disc is also called false twist disc, which is used in spinning During the twisting process, it plays a false twisting role, which can enhance the connection between the twisting plate and the stripping point of the condensation tank, and effectively prevent the occurrence of yarn breakage. Therefore, the arc surface and hole in contact between the twist plate and the yarn sliver are required to be very smooth to facilitate the formation and transmission of twist, and to reduce the frictional resistance to the yarn sliver and reduce the occurrence of end breakage.
4) Cotton transport channel
If the rubber of the cotton transport channel The sealing ring is damaged or falls off, which reduces the negative pressure in the spinning rotor, making it difficult to transfer and condense cotton fibers and causing yarn breakage. If there are gaps or burrs at the lower end of the steel column installed at the trumpet end of the cotton conveying channel, the phenomenon of hanging flowers will occur. The hanging flowers will accumulate into bundles and then enter the spinning rotor together with the negative pressure airflow. The consequences will be the same as the curved teeth on the opening roller. The impact is essentially the same.
5) The cotton feed roller and the cotton feed plate
If the gap at the lower end of the cotton feed roller shaft If there is oil between the magnetic plate and the helical gear or there is dust or dust accumulation on the lower end of the cotton feed roller, it will cause the sliver to get stuck during the conveying process. If the cotton feeding plate and eccentric pin are rusted or there is a lot of dust and lint embedded under the cotton feeding plate, it will cause the cotton feeding plate to move sluggishly. In severe cases, a dead jaw will be formed, and the control and control of the cotton sliver will be lost. Binding. The above two situations will cause abnormal cotton feeding and cause yarn breakage.
6) The installation position of the impurity discharge pipe is improper
According to the requirements, the impurity discharge port end and the spinning yarn A gap of 0.5 mm to 1 mm should be maintained between the outlet of the impurity discharge channel of the device, which is conducive to the elimination of impurities. If the distance is increased, too much air from the surroundings will be filled into the impurity discharge pipe, causing the airflow in the impurity discharge pipe to The speed slows down and the negative pressure decreases, which not only affects the separation of impurities by the carding roller, but also causes the neck of the impurity discharge pipe to be blocked by impurities, causing yarn breakage. The yarn breakage caused by the blockage of the trash discharge tube has a characteristic, that is, after the yarn is broken, there is a 60 mm to 120 mm long impurity yarn segment at the end of the yarn sliver.
7) The process exhaust hole of the spinning cup holder is blocked
If the The process exhaust hole is blocked, and the air in the spinning rotor cannot be discharged smoothly, forming a vortex in the spinning rotor, so that the air in the yarn drawing tube and carding cavity cannot flow well to the spinning rotor, affecting normal spinning and causing yarn damage. Beheaded.
8) Spinner process factors
The process requires the pressure on the cotton plate to be 26.5 N± 1.5 N for cottonThe distance between �� and the cotton feed roller is 0.05 mm～0.1 mm. The distance from the groove at the front of the cotton feeding plate to the opposite side of the carding chamber is 68.5 mm±0.1 mm. If any one of these three processes does not meet the requirements, it will cause abnormal cotton feeding, loss of control over the sliver, resulting in poor carding effect or the generation of slugs, which will cause yarn breakage.
03 Semi-finished product factors
1) Reasons for “Three Silks”
The raw materials used in rotor spinning are generally mixed with a considerable amount of reused cotton and scraps, and these raw materials contain relatively large amounts of “three silks”. Because the “three wires” are thicker and more rigid, it is more difficult for the rotor to twist them, so the formation and transfer of twists cannot be carried out, resulting in a twist-free zone and at the same time destroying the continuity between the whiskers. Sex may cause yarn breakage. If you observe carefully after decapitation, there will always be “three strands” at the end of the yarn.
2) Moisture regain rate of cotton sliver
According to the requirements, the moisture regain rate of cotton sliver is preferably 6.5 % ~ 8%, in this state, it is beneficial to the carding and transfer of cotton fibers by the carding roller, and it is also beneficial to the twisting of the spinning rotor. If the moisture regain of the cotton sliver is greater than 10%, the phenomenon of stuck fibers may occur, especially the difficulty of carding and transferring cotton fibers by the opening roller. The tooth ends of the opening roller are easily hung to form fiber bundles. When the fibers Once the bundle enters the condensation groove of the spinning rotor with the negative pressure airflow, yarn breakage will occur. </p
