Technology | Key factors for improving the quality of compact spinning yarns

As a new ring spinning method for improving the yarn quality, compact spinning has attracted more and more attention. How to improve the quality of the yarn is getting more and more attention from spinning companies. This article mainly introduces several common factors affecting the quality of compact spinning yarns.

1, negative pressure fan exhaust and negative pressure tube negative pressure

The negative pressure of the negative pressure tube is the most direct and critical factor affecting the quality of the compact spinning yarn. Facts have proved that the size of the negative pressure fan exhaust will directly affect the size of the negative pressure, in addition, the accumulation of wind inside the fan of the negative pressure fan is also a key factor affecting the negative pressure tube negative pressure, in daily production, the bellows must be cleaned in time Accumulate flowers and keep negative pressure stable. According to actual testing and production, it was found that the compact spinning negative pressure needs to be maintained at 24-30 mbar. Too low negative pressure will cause higher breakage rate, increased hairiness, long hairiness, and high uneven hairiness. According to actual measurement, under the same kind of temperature and humidity conditions, when the negative pressure is 24-27 mbar, the difference between the negative pressure at the front and the rear is about 1.5-3.5 mbar, and the difference in hairiness is about 30%. For example, the number of tail feathers of the C80S yarn is 812.20 roots/m, while that of the front end is 1,060.40 roots/m. The production practice has proved that the 1008 spinning frame can select 4.2kW ​​negative pressure fan, and the 512 spinning frame can choose 2.4kW negative pressure fan. Appropriately increasing the negative pressure fan speed can reduce the negative pressure difference between the front end and the rear end, and minimize the influence of the negative pressure difference on the yarn quality. Each sweep, the negative pressure tube on both sides of the tail can be removed 6-8 roots, open the negative pressure fan, the accumulation of accumulated flowers in the negative pressure inside the air cylinder to clean up.


2. The movement of the sliver on the negative pressure tube

The state of movement of the sliver on the negative pressure tube is a very important factor influencing the effect of the yarn sliver. In the case of a normal negative pressure, the sliver is transferred to the negative pressure tube during the roller and on the negative pressure tube. In the process of sports, the slivers move in a relatively straight and continuous state. However, due to certain factors, the state of movement of the bar will change.


2.1 The movement of the roller during the transfer to the negative pressure pipe

In actual production, due to factors such as excessive pressure on the cradle, electrostatic accumulation, poor surface of the roller, and negative pressure of the negative pressure pipe, etc., the “uncontrolled area” between the rollers and the negative pressure tube falls or skews. The phenomenon of yarn will be significantly affected. Therefore, the pressure of the compact spinning cradle should be kept small to prevent the accumulation of static electricity, maintain the surface smoothness of the roller and the roller, use ultraviolet rays to treat the roller, prevent sticking, and maintain the negative pressure of the negative pressure pipe properly.

  

2.2 The movement of the sliver on the negative pressure pipe

In actual production, there are sometimes phenomena such as a large increase in hairiness, a sharp increase in the breakage rate, or a complete break of the head. This is mainly due to the fact that the negative pressure fan has not been started or the negative pressure bellows have not been cleared in time and the negative pressure is too small. . Sometimes, some single spindles may have high breakage rate or they may not be able to spin normally. The main reason is that the negative pressure tube sucks at the output end of the air suction groove, and the accumulated flower in the grid circle can be cleaned. Try to use anti-static grid circles, use a reasonable number of grid mesh ring.

3, the impact of temperature and humidity in the workshop

In the compact spinning process, due to the action of the suction and exhaust air, the shop's temperature will be noticeably uneven at the front and rear. This unevenness will present a seasonal difference. The temperature difference in winter is about 2-4°C, and the summer season is about 3-6°C. Temperature and humidity are important factors affecting hairiness. According to actual measurements, the number of hairiness and nep in the rear of the vehicle is about 40% higher than that of the front end. See Table 1. Therefore, maintaining the normal temperature and humidity of the workshop and reducing the temperature and humidity difference is an important measure to improve product quality.

QQ screenshot 20150901111507

4, cradle pressure

The cradle pressure directly affects the quality of the yarn. If the cradle pressure is too high, the life of the front rubber roller will be shortened. This will cause the front roller to be concave and may also cause mechanical waves of the roller. The normal life cycle of the front rubber roller is about 2 months. When the pressure is too large, one and a half months will cause ineffective grip on the roving, resulting in a rapid increase in breakage. Therefore, the compact spinning should not increase the pressure, and the general control is 160-180N/spindle.

5. Effect of spinning process on yarn quality

  

5.1 The size of the floating area

Floating area is a key factor affecting yarn quality. The size of the floating area should be the same in size, the pressure bar should be in a proper position, and there should be no pressure bar grinding before the roller and long apron phenomenon. If the pressure bar is located behind, there will be an excessive floating area, which can not effectively control the fiber, and even a long apron phenomenon will occur. If the pressure bar is positioned too far, it will cause the roving to “run on”, and the pressure bar cannot be used. The role of the roller, if the pressure rod grinding front roller, will also cause the roller mechanical wave appears. In the production, the front roller of the rubber roller is about 2-3mm, and the maximum should not exceed 3mm. If the forward momentum is too large, it will easily form an anti-surrounding arc, which will cause the yarn quality to decline and increase the breakage. If the compact spinning floating area is too large, it will easily cause the front roller to press against the mesh ring. When the sliver moves to both sides of the guide thread movement, the sliver must oscillate from side to side in the suction groove, which affects the yarn quality.

  

5.2 Stretch draft multiple

Reasonable drafting is also an important factor in improving yarn quality. According to the experiment, in the spinning of 11.7 tex pure cotton yarns, there is a significant difference in the yarn quality in the rear draft multiples, see Table 2.

QQ screenshot 20150901111513

In the selection of draft multiples, we cannot blindly pursue good yarn stems and neps. With the continuous increase of draft multiples, the long irregularities in the yarn will increase. When selecting the compact spinning process, outside the critical draft multiple, the draft multiple in the rear zone can be appropriately increased, and the spindle speed can be appropriately increased, thereby increasing the yarn yield and improving the efficiency.


6. Conclusion


The optimization of yarn quality is a complex project, and the factors that affect yarn quality are also complex and diverse. Therefore, in order to optimize the quality of the yarn, it is necessary to consider it comprehensively to obtain the best yarn quality.


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