Selection of spinning process parameters, selection of combined linear density and draft multiple
1. Rolling Line Density If the rolling line density is too high, it is not conducive to loosening and removing impurities, and increases the drafting burden in the post-process. If it is too small, it will easily cause sticking holes in the roll and reduce the quality. Commonly used ranges are shown in Table 3-5. The yarn density of chemical fiber yarns should be heavier than that of pure cotton rolls of the same spun yarn to prevent roll sticking. One ship can use a cotton roll line density close to the spun yarns of pure cotton. The conversion relationship between semi-finished product basis weight (GK) and semi-finished linear density (Tt) is as follows: 2. Carding sliver linear density and draft multiple. If the linear density is too high, carding and impurity removal are poor, it is easy to block the coiling inclined tube, and the number of machines is too small, and there is no room for adjustment of the machine, which affects the production and quality of pre-spinning. If the linear density is too small, the fiber web will float and breakage will increase. The cohesion of chemical fibers is poor. In order to prevent the fiber web from drifting, when spinning chemical fibers, the linear density of fiber slivers should be larger than that of pure cotton slivers. The linear density and quantitative range of carded slivers of spun yarns with different linear densities are shown in Table 3-6. The drafting ratio of the carding machine should be appropriately increased, which can reduce the load on the cylinder and doffer needles and improve the carding efficiency. However, if the drafting ratio is too large, the fiber network will easily float and the number of machine equipment will increase. Generally, the draft ratio of the carding machine is about 1.23-1.5 times. If divided by raw materials, the draft ratio of pure cotton is 1.45-15, the draft ratio of polyester/cotton is 1.33~1.45, and the draft ratio of medium-long chemical fiber is about 1.23. 3. Pre-drawing linear density, draft multiple and number of combinations are generally 6 to 8, and the draft ratio is about 6-8 times. Increasing the number of combinations can improve the straightness and parallelism of the fibers in the small roll. Improve combed sliver quality and reduce combing noil rate. The pre-drawn linear density and basis weight of different spun yarns are shown in Table 3-7. 4. Small winding density, number of draft grids and number of combinations. If the thread density is too high, the load of the combing cylinder will increase, the difference between the inner and outer layers of carding will be large, the carding efficiency will decrease, and the number of equipment will decrease. The thread density is too small, the holding is poor, the carding is poor, the waste increases, and the small rolls stick together. The density of small rolls should be considered together with the cotton feed length. Generally, when the cotton feed length is long, in order to ensure the carding quality, the small roll thread density should be smaller; when the cotton feed length is short, in order to ensure the output of the combing machine, it should be larger. . The drafting multiple depends on the structure of the fed sliver. When the fibers are well straightened and parallel, the drafting multiple can be larger, otherwise, the drafting multiple can be smaller. Generally, the drafting multiple of the strip winding machine is 1.1~1.7 times, the drafting multiple of the doubling machine is about 6 times, and the drafting multiple of the strip doubling and winding combined machine is 2-5 times. The combined number of the strip coiling machine is 20~24, the combined number of the doubling coiler is 6, and the combined number of the strip coiling machine is 30-48. The density and quantitative range of small coils are shown in Table 3-8. 5. Combed sliver linear density, draft multiple and combined number. Generally, the linear density is smaller when spinning fine special yarns, and larger when spinning. When polyester-cotton blended chemical fiber fabrics are used, in order to ensure the correct blended chemical fiber fabric ratio between the combed sliver and polyester pre-drawn linear densities, the combed sliver linear density must be calculated. When using sliver blending, the linear densities of the two fiber slivers should be close to each other for good grip. The total draft ratio should be kept low to reduce additional unevenness caused by the draft of the combing machine. Generally 40-60 times. The number of combined combs for each combing machine: 3 for model A201D, 4 for model 5FA251A, 8 for model FA261 and 5XF]269A. The combing noil rate is generally 15%-20%. The cotton feeding length is related to the machine model and cotton feeding method, and can be selected according to actual needs. The linear density and quantitative range of combed strips are shown in Table 3-9.
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