The general principle of controlling short lint is “one reduction, one row”. “One reduction” is a proactive approach focusing on reducing short lint in process processing, which is more practical for increasing production capacity and reducing costs; “one row”, since it has been produced In order to ensure the quality of the yarn, we try to exclude fibers below 12.7 mm, although it will increase the cost of cotton.
The focus of emission reduction starts from the cleaning process or the blowroom and carding unit. Taking the blowroom-carding unit as an example, the short lint rate of the single equipment corresponding to catching, mixing, opening and cleaning in the process flow basically increases in synchrony with the increase in neps. By mastering the following 8 aspects, reducing lint emission can significantly inhibit the lint rate. knots are produced.
The fiber opening method implements a process that focuses on free opening and short processes. For example, the blowing and carding unit uses fewer striking points. The test also confirmed that free opening reduces lint by more than 1 percentage point and neps by 50% compared with holding blowing. %above.
Grasp the degree of dramatic increase in short lint in the blowroom-carding process, and follow the rules from large to small: main impurity removal machine or cleaning machine → cotton picking machine → double-axial flow cotton opener → cotton feeding box → multi-bin cotton mixing machine → Single-axial flow cotton opener, this choice is matched with a more reasonable and concise short process.
The use of beaters to impact the strength of fibers results in an increase in short pile: wing type > blade > tooth blade > sawtooth > brad nail > comb needle. Use less zigzag beaters with sharp edges and burrs, and use comb-type beaters or tapered sawtooth beaters, which can significantly reduce short lint. Changing the parallel U-shaped beater of the A035 type mixed cotton opener to the cylindrical nail beater can significantly reduce the wire rope. When the traditional porcupine rectangular blade processes fibers with poor maturity or fine fiber fineness, the cords increase, and the short lint and neps increase simultaneously. If it is changed to a nose-shaped beater, the number of blades increases from 228 to 1230, and the W is arranged in a cross, which has a combing effect. The impurity removal efficiency increased from 19.1% to 27%, the cotton bundle quality dropped from 31 mg to 14 mg, and the short lint rate of the cotton lap dropped from 18.2% to 16.5%. The combing needle roller can gently pierce the cotton layer, reducing fiber damage, saving 1 percentage point of waste and reducing neps by 20% compared with the sawtooth type. Compared with the sawtooth fixed cover, the needle-planted fixed cover plate has a higher tooth density as the tooth density increases. , the speed of the machine increases, the flow resistance of the front needle-type fixed flat plate comb increases to the fiber layer, and the holding force increases simultaneously, which is conducive to the directional straightening of the fibers, and the blackboard neps and short lint ratio are better than those of the zigzag fixed flat plate.
Use special equipment and airflow to eliminate short lint and knots. The cotton mesh cleaner has the function of excreting and balancing the longitudinal airflow on the surface of the cylinder. For example, by dynamically adjusting the cotton web cleaner during startup, the short lint impurities will appear in the spray shape in the cotton web cleaner, and the distance between the dust blade and the cylinder of the cotton web cleaner should be appropriately reduced, and at the same time, the guide cover should be appropriately increased (or Guide plate) and the cylinder distance, increase the thickness of the dust knife cutting airflow boundary layer, multiple rows of short lint and impurities.
Optimize process speed and speed ratio. The speed determines the degree of action of the beater and saw teeth on the fiber, and the fiber should be less damaged. The optimal speed configuration of cylinder, cover plate and lick-in roller can obtain the minimum neps and impurities. The speed ratio emphasizes two aspects: First, the speed ratio of the three cleaning rollers is optimized. In the early days, the speed ratio of the first, second, and third rollers was mostly 1:1.7:1.7, which was prone to fiber backflow and increased neps, so it was changed to 1:2: 2. The backflow is basically solved; 2. The speed ratio between the cylinder and the licker-in is sufficient to transfer all the fibers in the licker-in to prevent neps from being formed by rubbing. According to practice, the linear speed ratio of pure cotton is 2.1 to 2.2, and that of chemical fiber is 2.3 to 2.5.
A reasonable process to improve the directionality of cotton bundles in the cotton layer. Each cleaning machine is fed sequentially. In order to avoid damaging the fibers, the distance between the opening points is enlarged. The orientation degree of traditional cleaning cotton laps is better than that of the blowing and carding combined cotton layer, and less short lint is produced at the carding machine’s licker-in. Changing the traditional carding reverse feeding to forward feeding can reduce the stratification difference of the carded cotton laps and achieve flexible control of the cotton layer, which is beneficial to reducing fiber damage and short fiber.
The speed of high-yield carding machines has a certain speed limit. Rieter stipulates that taking into account the thermal expansion of fibers and cylinder rollers, when the cylinder speed exceeds 500 r/min, the distance related to the cylinder should be increased by 0.05 mm, otherwise long fibers will be easily damaged. Therefore, the pursuit of high yield and heavy weight may lead to simultaneous increases in short staple and neps.
In view of the poor orientation of the cotton bundles in the blowroom and carding joints, in order to avoid fiber damage, the distance between the licker-in roller and the cotton feeding plate is appropriately enlarged. In addition, it should be considered whether the carding feeding box can simulate the directional adsorption principle of airflow in the cleaning cotton roller dust cage to improve the consistency of the direction of the cotton layer of the carding machine. In fact, there is a contradiction between the elimination of neps and the increase of short lint in the carding process, and the growth of short lint during the carding process can only be controlled to a minimum extent.