The noil rate is closely related to product quality and production cost. Developing reasonable combing noil rate control methods to reduce combing noil rate while ensuring yarn quality is an important means for enterprises to reduce costs and increase efficiency.
1. Combing noil rate Control
1.1 Optimal control level of combing noil rate
1.1.1 Combing noil rate and yarn Definition of thread grade
Usually, the combing process with a combing noil rate of less than 12% is also called semi-combed yarn. This combing process mainly eliminates the waste in the slivers. Lots of lint. The noil rate of ordinary combed yarn is between 12% and 18%, and that of high-grade combed yarn is between 18% and 22%. When the noil rate is above 22%, the double combing process is usually used to produce 200-300 inch count (JLC2.9tex-JLC1.94tex) extra-fine yarn, which is used to make high-end, high-density, elastic and light yarn-dyed products. .
1.1.2 The relationship between the noil rate and the quality of combed sliver
Within a certain range As the combing noil rate increases, the short staple rate, neps, and impurities in the combed sliver decrease significantly, but when the combing noil rate exceeds a certain level, it continues to increase, and the combed sliver The improvement in quality begins to slow down or even remains flat. Therefore, the relationship between the waste rate and combed sliver quality is not a simple linear relationship, as shown in Figure 1.
▲Figure 1 The relationship between combing noil rate and combed sliver quality indicators
1.1.3 The relationship between the noil rate and yarn quality indicators
Yarn strength, stripe The dry uniformity improves with the increase of combing noil rate, and the improvement of yarn defects is very large. When the combing noil rate is within 10%, the improvement effect of yarn defects increases with the increase of combing noil rate. And significantly improved. However, after the combing noil rate increases to a certain level (the empirical value is about 15%), the improvement in yarn quality slows down, as shown in Figure 2.
▲Figure 2 The relationship between the increase in combing noil rate and yarn quality
1.1.4 Factors affecting combing noil rate
(1) Process adjustment: noil spacing, cylinder carding spacing Pitch, cotton feeding method, cotton feeding length, small roll ration, total draft ratio of the preparation process, main air duct negative pressure, cylinder positioning, nip opening amount, separation roller clockwise rotation timing, etc.
(2) Carding components: cylinder and top comb origin, specifications, tooth density, cylinder tooth surface angle, total carding points, nippers, top rollers, wool Brush status, etc.
(3) Raw material fluctuation: After the raw material batch is changed, the fiber length changes.
(4) Temperature and humidity: The temperature and humidity are too high or too low, etc.
1.2 The relationship between combing noil rate and yarn quality under different processes
1.2.1 Comparative test on combing noil rate and yarn quality of fine-staple cotton varieties
Variety : JC18.2tex, raw material: high-quality fine velvet cotton, JSFA286 combing machine, speed: 280 nip times/min, lap quantity: 72g/m, cotton feed length: 5.2mm. The test results are shown in Table 1.
It can be seen from the test data in Table 1 that when producing fine-staple cotton varieties, combing will The cotton rate decreased from 19.6% to 15.6%, the common yarn defects of the finished yarn did not change much, and the single strength increased slightly.
1.2.2 Effect of combing noil rate of long-staple cotton varieties on yarn quality
Variety JC7.9tex, raw material: 100% Xinjiang long-staple cotton, E65 combing machine, speed 310 nip/min, lap weight 71g/m, cotton feeding length 4.3mm, test results are shown in Table 2.
From the test data in Table 2, it can be seen that when producing 100% high-quality long-staple cotton quality 13 With a combing noil rate of around %, yarn quality is already at a critical point. If the customer’s quality requirements are met, increasing the combing noil rate will have little help in improving yarn quality.
1.2.3 Effect of noil rate on yarn quality under different process conditions
Variety: JC5.2tex; raw material: 70% long-staple cotton/30% fine-staple cotton; model: E65. The cylinders are S+U 9605/90° and Graf Primacom/111°. The test results are shown in Table 3.
From the test results in Table 3, it can be seen that the cylinder tooth surface angle is changed from 90° to 111°, and the combing area increases 23.3%. The total carding points increased from 32,400 teeth to 42,700 teeth, an increase of 31.8%, and the package yarn neps/km, IPI (L), and IPI (S) were significantly improved. Therefore, rationally expanding the tooth surface angle of the cylinder, increasing the combing degree of the cylinder of the combing machine, adopting the forward cotton feeding process and configuring the cotton feeding length of 4.7mm will help reduce costs and improve product quality.
1.2.4 The impact of waste rate variation on yarn quality
Variety: JC9.7The total draft of the winding machine is controlled within 1.5 times, and the total draft multiple of the preparation process is controlled within 8 times. Under the condition of satisfying the fiber straightness, it is ensured that no inconsistency occurs between the cotton layers during the combing and unwinding process. Adhesions.
(2) The combing machine has the characteristic of automatically adjusting the noil rate. When the combing noil rate fluctuates greatly, it is usually caused by the previous processes. An abnormality has occurred, so do not mechanically reduce the combing noil rate in order to achieve the noil rate target. An AFIS tester test should be carried out to detect the short staple content of raw sliver and combed sliver. Make corresponding adjustments based on the actual testing conditions.
(3) The key to combing noil control is to improve the quality of combing noil, that is, to increase the short staple rate of combing noil as much as possible. It is necessary to start from the aspects of machine processing and carding equipment to avoid excessive combing in the carding and combing processes, which will cause an increase in the short staple rate of the raw and combed slivers. At the same time, it is necessary to control the opening, cleaning, carding and combing processes. Knot and lint removal efficiency.
(4) The laboratory should test the noil rate once a week, and the noil difference between stations should be controlled within ±1%. Strictly implement the fixed table supply system for each process and the reasonable matching system of combed and large rolls. Reduce the table difference and eye difference of the noil rate of the combing machine. The correct way to measure the noil eye difference is: weigh the small rolls fed into the eight eyes with an electronic scale, record the weight of each small roll, collect the slivers output from each eye, and run the car for more than 10 minutes. , take out the cotton sliver from each eye and weigh it, and then weigh each small roll, so that the noil rate of each eye and the total noil rate can be accurately calculated.
2.2 Ensure the consistency of combing quality
Fine The consistency of the machine process on the combing machine directly affects the difference in noil rate between the combing machines (eyes), the unevenness of the combed sliver weight, the consistency of nep impurities and short staple rate. The combing process requires the initial position of the nip plate, the opening amount of the nip plate, the positioning of the cylinder bracket, the cylinder combing distance, the state of the brush bristles and the gap between the brush and the triangular air flow plate, the depth of the brush insertion into the cylinder, and the waste. The negative pressure of the main air duct and each eye branch air duct, the size of the trumpet mouth of the table, the height and entry distance of the top comb, the entry and exit distance of the cotton feed arc plate, the tooth direction of the ratchet at both ends of the cotton feed roller, the pressure at both ends of the top roller, and the pull Process parameters such as stretch roller distance ensure the consistency of the machine.
3. Conclusion
In the modern combing and combing process, the The heavy weight, high speed, low waste, and forward cotton feeding processes are beneficial to reducing costs and improving product quality. Forward feeding cotton has become the first choice for modern combing machine loading technology. </p
