Because chemical fibers have the characteristics of good uniformity, long length, and large friction coefficient between fiber and metal, the drafting force is large during the drafting process. Therefore, it is necessary to adopt measures such as “heavy pressure, large spacing, smooth channels, anti-entanglement and anti-blocking” on the process route. Only by increasing the pressure on the rollers and increasing the distance between the rollers can the stability of the drafting be ensured. Otherwise, problems such as low drafting efficiency, large evenness, increased weight unevenness, and even failure to open the draft and hard ends will occur. as a result of. While mastering the above process principles, you also need to pay attention to the following characteristics:
(1) Quantitative drawing The quantitative size of the blended sliver is a factor affecting the drafting force in the drafting zone. Due to the large drafting force and fluffy slivers of chemical fiber blends, the basis weight should be lighter than that of pure cotton, generally within the range of 12~21g/5m. According to the tests of some factories, after the dosing and roughing processes are quantitatively increased, the yarn weight unevenness and end breaks increase. The reason is due to unstable drafting efficiency, which shows that the equipment and technology cannot adapt to the weight quantification. However, when the pressure is sufficient and the machine is in good condition, appropriate weighting is also allowed.
(2) Front tension drafting and sliver arrangement sequence. Tension drafting must adapt to the resilience of the fiber. In the polyester-cotton blending process, the size of the tension draft is also an important factor affecting quality and efficiency. On the pure polyester pre-doubling machine, due to the large resilience of the polyester fiber, the fiber is stretched and deformed after drafting, and there is retraction between the front roller and the pressure roller. Therefore, the front tension draft should be small to prevent accidental draft. Stretch and wind the top roller. When the design is 1x or slightly less than 1x, life is normal and evenness is improved. On the mixing machine, due to the different elastic elongation of the two fibers, if only the requirements of polyester are met, the combed sliver will wrinkle due to too small tension, so the tension draft should be slightly greater than 1 times (generally 1.013 is used) times), the tension difference between the two can be reduced. The post-tension draft on a pure cotton spinning machine is generally about 1.22 times, and when the draw frame is used as a blender, it is 1 times. There is no sliver phenomenon, indicating that it is suitable for polyester-cotton blending.
When the slivers are mixed, the arrangement position of the slivers behind the first-pass mixer has a direct impact on the distribution of various fibers in the yarn and the quality of the yarn. For example, when the polyester-cotton blending ratio is 65/35, production practice has proven that when the positions of two cotton slivers among the six slivers on the first-pass mixing machine are arranged according to the second and fifth slivers, the radial unevenness of the two fibers is smaller. It is beneficial to improve the mixing effect. However, at this time, attention should be paid to the problems of hairiness and adhesion of mixed slivers after the second mixing machine.
(3) Generally speaking, when the drawing speed of spinning chemical fiber is too high, it is easy to produce electrostatic effects, causing winding of rubber rollers and winding rollers. In addition, abnormal and accidental drafting is prone to occur in the rear part of the machine. Therefore, the delivery speed of chemical fiber spinning is slightly lower than that of pure cotton spinning. </p
