Weak twist of spun yarn means that the twist is lower than the normal value. After the spun yarn is broken, the strength of the yarn is insufficient and the splicing is difficult.
Several situations of weak twist
Weak twist in one place: The thick details are caused by uneven drafting. During the twisting process, the twist is concentrated in the details. The twist at the thick places is small and the strength is low, or the details are too long, resulting in a fragmented twist coefficient and a low twist. Low strength. The long details caused by roving result in insufficient twisting and low strength during the yarn forming process. Weak twist of the entire single spindle: The single spindle is faulty and the entire yarn is thicker than the normal yarn. This type of yarn may be accompanied by friction on the steel ring. The entire machine has weak twist: caused by process errors. Judging from the actual production process, the ones that have a greater impact are weak twist in one place and weak twist in the entire ingot. If a weak twist in one place cannot be connected, the lathe will have a big opinion; the entire single spindle is weakly twisted because it rubs the steel ring during forming, so it is not easy to be found and removed. This is the key task to control the weak twist; the weak twist in the entire machine is not easy to occur, and it is easy to When detected, there is generally no negative impact.
The dangers of weakly twisted yarn
The hazards of weakly twisted yarn include the following aspects: ① The strength decreases; ② The yellow and white sections are produced, and the contrast becomes more obvious after color absorption; ③ The repeated breakage of the spun yarn increases; ④ The grinding of the ring yarn is easy to occur; ⑤ The knitting and weaving machine breakage Increase; ⑥ Weak twist is easy to produce hairiness; ⑦ Weak twist is easy to produce cotton balls (neps); ⑧ When weakly twisted yarn is used as warp yarn, because it absorbs a lot of color, it will produce long warp color.
The main factors that produce weakly twisted yarn
The main factors that produce weakly twisted yarn are as follows: ① The spindle belt is too long; ② the spindle belt runs to the large diameter of the spindle plate; ③ the spindle bladder is damaged, causing spindle rotation failure; ④ the position of the weight scale of the tension wheel of the spindle belt is too small, making the tension wheel tension too small; ⑤ the yarn tube is defective, resulting in The tube jumps; ⑥ There are too many flying particles adhering to the spindle belt; ⑦ There is oil stain on the spindle; ⑧ There is oil stain on the rolling plate.
Main factors affecting yarn twist unevenness
The main factors affecting uneven yarn twist are as follows:
a) When the roving frame does not use a false twister, the twist in the spinning section is far lower than the process design twist, causing normal spinning The roving elongation is also larger (generally greater than 2%). This is mainly because the top of the spindle flyer is the twisting point. The greater the friction at the top of the spindle flyer, the stronger the twisting phenomenon of the yarn sliver.
b) The evenness of the spun yarn is poor, especially the occurrence of thick spots and fine details, which have a greater impact on the twist unevenness of the yarn.
c) Uneven spindle speed is an important reason for uneven twist in yarn. Uneven spindle speed is mainly caused by the difference in slippery rate between rollers, spindle conditions and spindle belt reels. The main factors affecting the slippery rate are the tension of the spindle belt, the quality of the inner and outer layers of the spindle belt, the taper of the spindle tip and the spindle Differences in disc diameter and spindle lubrication conditions.
d) The influence of spindle belt length and spindle belt tension on spindle speed: If the spindle belt tension is large, the slippage rate between the spindle belt and the roller plate will be small, and the slippage rate between the spindle plate and the spindle belt will be small. If it is small, the spindle speed will be high, so the twist of the yarn will be large. On the contrary, the yarn twist is small.
e) The influence of the length of the spindle belt on the tension of the spindle belt: the longer the spindle belt, the smaller the tension of the spindle belt, and the shorter the spindle belt, the greater the tension of the spindle belt. If the spindle belt lengths of the spinning frame and the twisting machine on the same machine are inconsistent, it will cause a large difference in the tension of the spindle belts on the same machine, resulting in uneven spindle speeds on the same machine, which will affect the uneven twist of the yarn. Poor lap of the spindle tape, twisted and damaged burrs, excessive adhesion of fly flakes on the spindle tape, oil stains on the spindle, etc., which cause the spindle and the spindle tape reel to rotate inflexibly, beat, etc., will all affect the twist unevenness of the yarn. produce a certain degree of impact.
f) Poor contact between the spindle and the bobbin, the inner hole at the top of the bobbin is worn or not rounded, the weight is too light, the spindle rod is bent and the spindle runs unstable, etc., which will cause the bobbin to jump during operation. The tube or “invisible skipping tube” causes the yarn twist unevenness to rise.
g) Due to a weak sense of work responsibility and lax management of the workshop laboratory, the wrong number of twist conversion teeth was used, resulting in a large number of strong and weak twisted yarns, that is, wrongly twisted yarns.
Technical measures to reduce yarn twist unevenness
a ) In the roving process, the roving tension should be constantly checked and adjusted, and a new type of false twister should be used. On the premise that the fine yarn does not produce hard ends, the roving twist should be appropriately large. Appropriately increase the moisture regain of the roving to maintain a good roving structure. That is, the separation and parallel straightness of the fibers in the roving are good, which reduces the internal stress after fiber drafting and reduces the adverse effects of the large torsional and bending stiffness of synthetic fibers on the twisting of the spun yarn, thereby reducing the twist unevenness.
b) Use new types of rubber rollers and aprons, such as low-hardness, high-elasticity non-processing rubber rollers and internal and external pattern aprons. And according to the yarn variety and raw material properties, the hardness of the rubber roller is reasonably selected. To strengthen the effective grip and control of fiber movement, reduce slippage, improve yarn quality, and reduce twist unevenness.
c) Use a new type of spindle belt, and ensure that the specifications of the spindle belt are correct and the material is of high quality, so that the tension of the spindle belt is consistent, the slippage rate of the spindle belt is reduced, and the difference in spindle speed between spindles is reduced.
d) In the actual production process, it is necessary to strengthen the management of spindles. Spindle discs with different diameters cannot be mixed, and the position of the spindle tape disc and the scale of the tension weight must be consistent. In order to ensure consistent tension of the spindle belt, it is necessary to adjust the twist of the spindle belt and make the spindle belt run basically in the middle position of the spindle tray. The spindle foot should be refueled in conjunction with the wiping cycle to ensure flexible rotation of the roller plate, spindle belt plate and spindle. </p
