Abstract: The moisture absorption and release status of fibers during the production of fine-staple cotton high-count yarn was analyzed, and the temperature and humidity adjustment, exhaust airflow adjustment, and moisture regain control of semi-finished products in each process during the production of fine-staple cotton high-count yarn were discussed. requirements.
Our company’s leading product is fine velvet cotton high count yarn. In order to ensure product quality, we We have conducted a series of explorations on technology, equipment, temperature and humidity adjustment, etc., and accumulated rich practical experience. Now we will share with you some of our experiences in temperature and humidity management.
Fine-staple cotton has shorter and thicker fibers than long-staple cotton. When spinning high-count yarns, the number of fibers in the yarn cross-section is reduced, and the cohesion between fibers is weak and the strength is low. . In order to solve this problem, in addition to detailed adjustments in processes and equipment, a lot of work also needs to be done in each process in terms of temperature and humidity control.
1. Blowing and carding process
Raw cotton moisture regain and opening There is a great relationship between the loosening and impurity removal effects. If the moisture regain is too small, it is conducive to loosening and impurity removal, but it will easily damage the fibers, causing an increase in the amount of short lint and noil; if the moisture regain is too high, the fibers will adhere, which is not conducive to loosening and impurity removal. . According to the moisture regain rate of raw cotton, insulation and humidification of cotton bales should be done in the workshop to lay a good foundation for the opening and impurity removal of the blowroom and carding unit.
The task of the air conditioner in the blowing and carding process is to ensure that the cotton fiber is not easily broken during the blowing and carding process, and is conducive to the removal of impurities and short lint. Therefore, the temperature and humidity of the workshop environment are controlled The overall idea follows the law of adding moisture to pure cotton spinning. Generally, the relative humidity in the cleaning process is controlled at 55-65%, and the carding process is controlled at 50-55%, so that the fiber production process is dry outside and moist inside. The wet state enhances the softness and impact resistance of the fiber, which is beneficial to the carding of the fiber and the removal of impurities. In winter, the outdoor ambient temperature is low, the pre-spinning equipment generates little heat, and the workshop is prone to low temperature and low humidity, which will cause the fiber to become brittle and break, increase the amount of noil, and affect the strength. In the blowing and carding unit, the methods we use to raise temperature and humidify are:
(1) Strictly control the air supply and exhaust volume of the air conditioner, and reuse all process dust removal air to ensure Avoid heat loss in the workshop and ensure that the temperature in the blowroom and carding workshop reaches above 26°C.
(2) Transport the relatively high-temperature spray circulating water of the spinning yarn to the air-conditioning room of the blowing and carding unit through pipelines, so that the temperature of the spray water in the blowing and carding unit can be increased to above 24°C. Improve the heat and moisture exchange efficiency of air conditioning supply in the spray room.
Through these two measures, the temperature of the blowing and carding process is controlled at 25-28°C, and the relative humidity is controlled at 60-70%. The moisture regain of cotton slivers is stable at 6.5-6.8%. Lay a good foundation for the next process.
Combining and roughing process
Requires fibers with softness and strong cohesion , the characteristics of easy twisting to improve the roller’s control over the fiber and improve the straightening and parallelism of the fiber. Under normal circumstances, the relative humidity in the roving process should be controlled on the high side so that the spun yarn can maintain a dehumidifying state of internal moisture and external dryness. Internal moisture can make the cotton fibers soft and conductive, and will not affect the normal arrangement of fibers due to electrostatic effects. Evenness is good; external dryness can reduce the friction and adhesion between fibers, which is beneficial to drafting and impurity removal. Appropriately increasing the moisture regain of roving will help improve the drafting efficiency of fine yarn and achieve high quality and high yield.
If the relative humidity and moisture regain in the roving process are too small, it will cause problems such as increased roving fly, increased end breakage rate, and messy yarn. However, if the relative humidity and moisture regain are too high, it will This causes problems such as the top rollers being easily entangled and the whiskers not being able to be stretched. Therefore, strict humidity control standards should be formulated without affecting life and spinning technology. The roving temperature should be controlled at 28-30°C, the relative humidity should be controlled at 63-68%, and the roving moisture regain should be stable at 6.5-7.0% all year round. The control index will not be significantly adjusted due to seasonal changes, providing good conditions for moisturizing, twisting and drafting of the spun yarn.
Spinning workshop
Requires relative humidity ratio and rough process relative humidity Small, it keeps the roving in a dehumidification state of internal moisture and external dryness in the spinning workshop, ensuring that the fiber is soft and non-sticky, easy to process, and has good conductivity. At the same time, it has small friction and adhesion, which is beneficial to drafting.
In the spinning process, due to the high temperature in the workshop and the long spinning cycle, the cotton fiber releases a lot of moisture during the drafting and twisting processes. If the relative humidity is too small, the cotton fiber will easily Escape, fly flowers increase, and static electricity is easily generated during the drafting process, which affects the straightness of the fiber and the tightness of the slivers. The yarn evenness deteriorates, hairiness increases, it is easy to wrap around the top roller, and the strength decreases. The methods we adopt are:
(1) Increase the relative humidity in the workshop and increase the number of air changes in the spinning process. The relative humidity is controlled at 58-63% and the number of air changes is maintained at 20 -26 times/hour, improves the cleanliness of the air in the workshop, stabilizes the moisture regain of the sliver, and ensures the yarn strength and quality indicators.
(2) Solve the problem of temperature and humidity differences in the workshop. Through long-term measurement, statistics and analysis of temperature, humidity and moisture regain of semi-finished products in different areas of the workshop, we found that when the temperature and humidity readings in each area are basically the same, the actual moisture regain and strength of the yarn at the head, middle and tail of the spinning machine There are differences. To this end, we aim to ensure the consistency of the moisture regain of semi-finished products in each area and make targeted adjustments to the temperature and humidity indicators in different areas to stabilize the moisture regain of the spun yarn at 6.3-6.5%. The yarn in each area Line strength consistency has also been improved.
（3）��Adjustment of the air supply speed of the air conditioner. During the production process, we found that unstable airflow in the workshop would cause an increase in yarn breakage, thus affecting yarn strength. To this end, each air supply outlet was tested multiple times with an anemometer and adjusted repeatedly to ensure that the wind speed of all air outlets in the workshop was stable within the range of 3.0-3.5m/s, eliminating the difference in air supply at each outlet of the air supply duct. , ensures the stability of the air flow in the workshop, and controls the relationship between exhaust and air supply at the same time, so that the air flow in the workshop basically maintains a slightly positive pressure state, eliminates the impact of regional temperature and humidity differences and external air flow on the workshop, and improves the strength of the spinning yarn Consistency creates good environmental conditions for high speed and high production.
(4) Solve the impact of airflow turbulence at the front of the spinning machine on the quality of high-count yarn. The high-speed airflow generated by the spinning roller can easily blow away the lint on the machine or in the turning lane to form flying flowers, which not only affects the overall environment of the workshop, but also blows to adjacent machines, causing accidental end breaks or yarn defects, affecting production. efficiency and product quality. In order to solve this problem, we developed and implemented a technical improvement plan through testing: we dug a special air duct at the entrance of the car lane, installed a slit-type fly interception suction port (see Figure 1), and connected the exhaust fan. Without increasing the energy consumption of the fan, through the negative pressure effect of the air suction port in the workshop, the secondary flying dust caused by air flow turbulence is effectively controlled, which plays a positive role in stabilizing product quality and improving the workshop environment.
Figure 1 Slit-type fly interceptor air suction port
4. Automatic winding process
The speed of the automatic winding machine is high, and the yarn is exposed to high temperatures during the winding process. After friction, there is a tendency to release heat and absorb moisture. Therefore, increasing the relative humidity in the workshop can realize the moisture absorption of the yarn during the heat release process, which can increase the strength and moisture regain of the yarn, which is beneficial to ensuring the strength of the yarn, removing yarn defects, making the yarn surface smooth and reducing hairiness.
We control a high relative humidity in the winding process. On the premise of ensuring the air exchange rate of about 20 times/hour in the workshop, the air conditioning air supply adopts low supply and slow discharge adjustment. The concept makes full use of the advantages of self-controlled air conditioning to maintain stable temperature and humidity in the workshop under various weather conditions such as outdoor seasonal changes and large changes in temperature and humidity between day and night. Without affecting the normal operation of the electric cleaner, maintain a stable high-humidity environment. The temperature and humidity control range is: temperature 28-30°C, relative humidity 70-75%, so that the cotton yarn can absorb moisture stably during the winding process and ensure the strength. .
We also created our own energy-saving finished product humidification method, built a special humidification room, and guided the 90°C high-temperature waste heat air from the air compressor to the special spray room through pipelines. It makes use of the waste heat of the air compressor and ensures the high-temperature and high-humidity environment required by cotton yarn in the humidification room. The temperature and humidity index of the finished humidification room is stable at 27-30°C, and the relative humidity is maintained at 90-95% (see Figure 2) . In order to ensure the quality of humidification, the three principles of “timing, temperature and humidity” have been formulated. The cotton yarns entering and exiting the humidification room are weighed one by one, the humidification time is strictly controlled, and the implementation supervision is strengthened to ensure the consistency of the moisture regain of the finished yarn. This further ensures the strength of the yarn.
Figure 2 Dedicated humidification room for energy-saving finished products
5. Conclusion
In the process of spinning high-count yarn from fine velvet cotton, air conditioning plays an important role that cannot be ignored. Function, the moisture absorption and release characteristics of cotton yarn during the production process should be reasonably controlled to ensure appropriate moisture regain rates of semi-finished products in each process, reduce regional moisture regain differences caused by mismatched air supply and exhaust, and try to ensure the consistency of moisture regain rates of semi-finished products and finished products. , to create good environmental conditions for fine velvet cotton spinning and high count yarn. </p
