Production Points And Process Quality Control Method Of Strong Twist Yarn

The twist is mainly used to make the weft yarn wrinkle. Due to the above unique functions, strong twist yarn as a special yarn has always occupied a place in the yarn market. Strong twist yarn can be produced without improving equipment and adding accessories. The technical content and added value of the products are high. However, it is difficult to produce strong twist yarn and the product quality is difficult to control. The production enterprise must have certain technical ability and management experience.

　　01

Front Spinning

The pre spinning production process and quality control of strong twist yarn are basically the same as that of conventional yarn, but the twist factor of spinning yarn exceeds the critical twist factor of yarn, and the yarn strength is lower than that of conventional woven yarn. The larger the twist factor is, the lower the yarn strength is, the higher the weight CV and strength CV value are. Meanwhile, in order to obtain relatively high production efficiency, the spinning speed is generally not lower than that of the same number of woven yarns 。 The above factors increase the spinning end breakage and increase the production difficulty. Therefore, the cotton blending grade of strong twist yarn should be higher than that of the same woven yarn. In general, the delivery time of strong twist yarn is short, and the batch is small, sometimes it is difficult to separate cotton blending. At this time, Combing Noil should be increased, and the drawing frame and roving frame with good mechanical condition should be selected to organize production. Roving quality is the guarantee of the quality of strong twist yarn.

　　02

Spinning

　　1

Yarn twist

The twist degree of above 5 is defined by the fabric manufacturer according to the specific requirements of the fabric fabric. Due to the factors such as the slip rate of spindle belt, in order to meet the twist requirements of customers, the calculation twist of spinning yarn should be generally larger. The twist factor of strong twist yarn is larger, that is to say, the twist angle is larger, and the stress distribution of inner and outer layer fiber is seriously uneven. In the test of untwisting and twisting, some fibers move and can not be restored to their original state. Sometimes, there are false high twist values, which need to be eliminated at any time during the test.

In daily production, the process management should ensure the accuracy of spinning process parameters, equipment management should eliminate the skew spindle, firmly attack the "fierce" spindle, keep the tension of the spindle belt uniform, the spindle belt joint is good, so that the average twist value is basically stable, and the twist CV value is maintained at a good level. The twist CV value of spinning directly affects the CV value of single strength and weight.

　　2

Spinning quality (weight) control

The drafting efficiency of spinning frame is affected by many factors, such as raw material, mechanical state, process, temperature and humidity, among which the drafting efficiency of yarns with different twist coefficient is quite different due to twist shrinkage. The twist shrinkage of strong twist yarn is large, and the drafting efficiency is generally 85% - 92%. Only by mastering the drafting efficiency of spinning varieties can the weight deviation be effectively controlled and the yarn meeting the specified weight requirements can be produced. In the process design, the drafting efficiency is considered according to the experience, and the draft change gear is initially determined. Sample in time for weight test and adjust process gear during production.

　　3

Winding density of tube yarn

The winding process of tube yarn needs to be tightly wound, with clear layers and no entanglement. The unwinding in the later process does not take off the coil, and the package size is appropriate. If the package size is too large, the yarn is easy to grind the steel ring, resulting in bad yarn; if the package size is too small, the number of doffing and tube changing increases, the labor intensity increases and the production efficiency decreases. Strong twist yarn has large twist, high compact density, good elasticity and small cross-section diameter, and the tube yarn forming is obviously small. When the tube is full of doffing, the automatic doffing car can not pull out the bobbin normally, resulting in the increase of doffing workload and the production efficiency. The winding density of tube yarn must be increased properly.

　　4

Control of spinning end breakage

The average strength of strong twist yarn is lower, the CV value of strength is larger than that of the same number of woven yarn, the breakage rate of spinning yarn is high, and the joint is difficult. More broken ends affect the yarn output and quality, and increase the labor intensity of the stop workers. Therefore, great attention should be paid to the operation and management.

It has been proved by practice that the spinning frame with variable frequency speed regulation technology can reduce the spindle speed when spinning large and small yarns; select the machine whose ring is in the ripening period, appropriately shorten the replacement period of the bead; strengthen the maintenance and patrol inspection, and timely correct the skew spindle, cot concave, apron deviation, yarn guide hook loose, and yarn guide hook not smooth and clean, which are effective measures to reduce spinning breakage. The output is not high when the strong twisting stage is used, and the pressure of the stop worker to change the roving yarn is not big. Therefore, we should concentrate on the cleaning of the machine, strengthen the tour and connect the broken ends in time.

　　03

Winding

The winding machine should be adjusted one by one and checked and accepted one by one to ensure that all parts and components of splicing are coordinated and the equipment is in good condition. The phenomenon of untwisting and untwisting at the end of strong twist yarn winding is easy to occur, and the yarn joint is climbing. It is necessary to ensure the air pressure of untwisting and twisting. The scale of untwisting and twisting should be adjusted from the maximum point, and the lap length should be adjusted to the best. Strong twist yarn has high elasticity, and the winding pressure should be less than 50 MPa. Strong twist yarn has low strength, many yarn defects, frequent electronic yarn cleaning, and lower winding speed than conventional yarn. There are many neps and impurities in the conventional strong twist yarn, which is lower than the production efficiency of the same number combed strong twist yarn.

In a word, strong twist yarn has high technology content and is difficult to produce and process. It is necessary to do a good job in basic technical management such as the operation of process equipment, strengthen the maintenance of spinning equipment and reduce the difference between spindles. In order to improve the quality of the joint and reduce the phenomenon of yarn head climbing at the spliced part, the air pressure of untwisting and twisting should be ensured, and the lapping length should be adjusted properly.