It is impossible to completely avoid the breakage of the sliver in the production of rotor spinning. After the yarn breaks, the yarn yield, quality and production rate must have a certain impact. The higher the yarn breakage rate, the greater the damage. Therefore, the occurrence of broken ends should be minimized in production. The following is an analysis of the causes of spinning breaks in self-draining rotor spinning machines.
-01- Process factor
1) Spinning speed
When the strip is peeled and twisted, it will strongly rub against the cotton sump. The higher the rotor speed, the greater the frictional resistance, which makes it difficult to peel and twist the strip. Therefore, the higher the speed of the spinning of the cup, the more the yarn breaks.
2) Yarn speed
The speed of the yarn is determined by the size of the twist. In a certain range, the twist is large, the strength of the yarn is high, and the yarn breakage during the spinning process is less. When the sliver is transitioned from the whisker to the sliver in the initial stage of twisting, the strong effect of the twist on the sliver is particularly important. Therefore, the faster the yarn feeding speed is, the higher the yarn breaking rate is when the other conditions are constant.
3) Cotton
Most of the raw materials used in rotor spinning are low-grade cotton and a part of recycled cotton. These raw materials are rich in impurities, dusty, and the rate of short pile is high, and the length of the main body of the fiber is short and the strength is low, which increases the spinning. The difficulty of the yarn also increases the chance that the yarn will break. Therefore, increasing the cotton blending level under other conditions can significantly reduce the occurrence of yarn breakage.
-02- spinning machine working condition
1) Spinning cup
The working condition of the rotor cup has an important influence on the level of the yarn and the breakage of the yarn. If there are many impurities and small dust clusters in the cotton tank, then the fiber distribution into the cotton tank is Non-uniform, when the strip of cotton fiber is less distributed, its strength must be lower when it is peeled off. In another case, the peeling of the oxide layer in the condensing tank is rough due to the excessive use or improper use of the rotor, and the peeling of the cotton fibers embedded in the condensing tank is very difficult. Both of the above conditions destroy the contact force between the strips and increase the difficulty of the formation and transmission of the twist. When the strength of the strip can not overcome the frictional resistance of the cotton tank, the yarn will break.
2) Sewing roller
The opening and closing roller racks should be smooth and sharp, which is beneficial to the carding, sorting and transfer of the fibers. However, in the production process, the opening roller inevitably produces the phenomenon of inverted teeth and curved teeth. These hooks are very unfavorable for the transfer of cotton fibers, and the cotton fibers are gathered to form a cotton bundle. If the cotton bundle enters the spinning cup with the negative pressure airflow, Its mass is relatively large, so its centrifugal force and frictional resistance are also large, which increases the difficulty of peeling and twisting, and causes the yarn to break. The broken head produced by the hooking of the opening roller has a small cotton bundle at the end of the yarn.
3) Resistance plate
The baffle plate is also called a false twist plate, which plays the role of false twist in the process of spinning and twisting, which can enhance the connection between the bar to the peeling point of the cotton baffle and effectively prevent the yarn from breaking. occur. Therefore, it is required that the arc surface and the hole in contact with the sliver are very smooth, so as to facilitate the formation and transmission of the twist, and reduce the frictional resistance to the sliver and reduce the occurrence of breakage.
4) Cotton channel
If the rubber sealing ring of the cotton conveying passage is damaged or peeled off, the negative pressure in the spinning cup is lowered, which makes the transfer and agglomeration of the cotton fiber difficult, and causes the yarn to break. If there is a gap or burr at the lower end of the steel column at the flare end of the cotton conveying channel, the hanging flower will be formed. The hanged flower will become bundled and enter the rotor together with the negative pressure air flow. The result is that there is a curved tooth on the opening roller. The impact is basically the same.
5) Feed cotton roller and cotton board
If there is oil between the magnetic separator and the helical gear at the lower end of the cotton roller shaft, or there is dust and accumulated flowers at the lower end of the cotton roller, it will cause a doping phenomenon during the process of transporting the sliver. If the cotton board and the eccentric pin are rusted or the dust and lint are embedded in the underside of the cotton board, the action of the cotton board will be sluggish, and when it is serious, the dead jaw will be formed, and the control of the sliver should be lost. Binding force. The occurrence of the above two conditions will cause the cotton to be abnormal and the yarn to be broken.
6) Improper installation position of the exhaust pipe
A clearance of 0.5 mm to 1 mm should be maintained between the end of the discharge port and the exit of the spinning device, so that the removal of impurities is facilitated. If the distance is increased, the surrounding air will be filled into the exhaust pipe. Too much, the airflow speed in the exhaust pipe is slowed down, and the negative pressure is lowered. On the one hand, the separation of the impurities by the opening roller is affected, and at the same time, the neck of the exhaust pipe is blocked by impurities, thereby causing the yarn to break. head. The yarn breakage caused by the blockage of the discharge pipe has a characteristic that there is an impurity yarn section of 60 mm to 120 mm long at the end of the yarn after the breakage.
7) The technical exhaust hole of the spinning cup holder is blocked
If the process air vent of the rotor cup is blocked, the air in the rotor cannot be smoothly discharged, and a vortex is formed in the rotor, so that the air of the yarn feeding tube and the combing chamber cannot flow well to the rotor, which affects the normal. Spinning causes the yarn to break.
8) Spinning process factors
The process requires that the pressure of the cotton board is 26.5 N±1.5 N, and the distance between the cotton board and the feeding roller is 0.05 mm to 0.1 mm. The distance from the front end of the cotton sheet to the opposite side of the carding chamber is 68.5 mm ± 0.1 mm. If one of the three processes does not meet the requirements, it will cause the cotton to be abnormal, lose the control effect of the sliver and cause the combing effect to be bad or the thick knot will cause the yarn to break.
-03- semi-finished factors
1) "Three Wires" Reason
The raw materials used for rotor spinning are generally mixed with a considerable amount of recycled cotton and scrap, and the "three filaments" contained in these raw materials are relatively large. Because the "three wires" are thicker and more rigid, it is more difficult to twist them by the rotor, so the formation and transmission of the roundabout cannot be carried out, resulting in a flawless zone and at the same time destroying the continuity between the strands. Sex causes the yarn to break. If you look carefully after the break, there is always the presence of "three wires" at the end of the sliver.
2) Cotton tamp regain
The moisture regain rate of the sliver is preferably between 6.5% and 8%. In this state, it is advantageous for the carding and transfer of the cotton fibers by the opening roller, and also for the twisting of the spinning cup. If the moisture regain of the sliver is more than 10%, the phenomenon of blocking fibers may occur, especially the difficulty of combing and transferring the cotton fibers by the opening roller, and the fiber ends are easily hanged at the tooth ends of the opening rollers, when the fibers are Once the bundle enters the rotor dam with the negative pressure airflow, the yarn ends are broken.
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