Lint cleaning The impact of sawtooth lint cleaning machine on cotton quality
The benefits of using a saw-tooth lint cleaner to the ginner have been described before, but the damage to cotton quality caused by the traditional saw-tooth lint cleaner cannot be ignored. The lint cleaning process reduces the impact on cotton fibers. Damage has always been a concern for fabric manufacturers. Many technicians, especially many experts on fabrics, believe that the emergence of lint cleaning machines has not only failed to improve cotton quality, but has had a negative impact on cotton quality.
(1) Side Effects of Lint Cleaning Machine
1. After being cleaned by the saw-tooth lint cleaning machine, there will be an increase in irresolvable defects. Impurity removal and carding have always been completed by two processes: blowing and carding in fabric production. . According to different linear densities and different product qualities, cotton textile enterprises achieve the purpose of controlling product quality by setting the number of openings and blowing methods in the process. In order to prevent impurities from breaking, they generally arrange loosening first, free blowing, and then holding. blow. The saw-tooth lint cleaning machine violates this principle of cleaning and carding. It mainly uses holding and blowing. Although the impurities in the raw cotton are partially removed, the coarse impurities are broken into many small impurities, small white stars and Neps, cords, etc., and impurities and defects such as stiff pieces, soft skin and neps, which are also difficult to remove in the carding machine, not only cannot be reduced, but increased after cleaning by the lint cleaning machine. As a result, after the lint cotton cleaning machine was cleaned, although the impurity content rate decreased, the total number of defects per 100 grams increased sharply, and neps and cords increased significantly, resulting in an increase in spinning neps and impurities.
2. The use of sawtooth lint cleaning machines is not conducive to the quality of the ginning process
The use of lint cleaning machines can only cover up the shortcomings in the appearance of the cotton and cannot improve the quality of the ginning process. In actual work, cotton finishing companies will relax For the cleaning of lint, sometimes even some of the lint cleaning and impurity removal equipment is cancelled, the ginning speed is increased, and the heavy responsibility of covering up the poor quality of the ginning process is transferred to the lint cleaning machine. Although this can save ginning costs and improve economic benefits, it The quality of raw cotton has dropped significantly.
3. Damage various length indicators and specific strength of cotton
Saw-tooth lint cleaning is to fully comb and remove lint fibers through the cooperation of saw-tooth rollers and debris removal knives. During the process of picking out fibers, It is very easy to break the fibers. Tests have shown that compared with uncleaned lint, the main length of cleaned lint is reduced by 0.3 to 1 mm, the quality length is shortened by about 1.5 mm, and the short lint rate increases by more than 2%. In the cleaning process of the fabric factory, short lint will become As the times increase, the breaking strength of the fiber also decreases. This is mainly because the lint is hit by the licker-in roller in the lint cleaning machine, and some fibers are damaged, and some are even broken. Some damaged fibers are broken when they are hit again during fabric finishing, especially in the carding process, forming Short velvet.
The loss of these indicators of lint has direct harm to the fabric process. On the one hand, it will cause the spinning line to deteriorate, hairiness to increase, and the single yarn strength to decrease; on the other hand, during the spinning process, the drop will increase. The amount of cotton increases the cost of spinning. In the past, the main body length of most Xinjiang cotton was in the long range of 29mm. Now, after cleaning by the lint cotton cleaning machine, the main body length is in the short range of 29mm. This not only destroys the cotton resources, but also affects the performance of the fabric.
4. Increased foreign fibers and color defects
In the lint cleaning machine, some fibers will be broken by the licker-in roller, and foreign fibers will also be broken, because foreign fibers and colored fibers have fine and Due to their long and light characteristics, the fibers are more easily broken and broken than cotton fibers during the cleaning process, thus increasing the number of foreign fibers and color defects, making it more difficult to sort in fabric factories.
Due to the above reasons, many fabric factories in Xinjiang, my country are trying to use contracts to specify that lint cleaning is not required or only partial cleaning is required to reduce the short fiber rate.
The country has proposed that from January 1, 2004, the cotton quality requirements for the mandatory national standard “Cotton Fine Staple Cotton” will be increased
Two new indicators – short fiber rate and neps, Although it has not been implemented due to various reasons, the “Instrumented Inspection of Cotton”
(draft) puts forward requirements for neps and short fiber index, which shows that the ginning process must be strict and unreasonable lint cleaning must be controlled during ginning. It is a general trend to reduce the damage to fibers caused by lint cleaning.
With the increase in the cost of manual cotton picking and the improvement of machine cotton picking equipment, in the near future, our country will also promote machine picking cotton in an all-round way.
Since machine-picked cotton contains a lot of impurities, it must go through two or more lint cleanings. Therefore, it is impossible to cancel lint cleaning. Reducing the damage to fibers caused by lint cleaning is the direction of our research.
(2) How to reduce the damage to fibers caused by lint cleaning
1. Use the lint cleaning machine flexibly
(1) It should be used flexibly according to the impurity content of lint. When the cotton is relatively clean, lint cleaning does not need to be performed. For example, manual picking of cotton can avoid or eliminate the process of lint cleaning machine; pay close attention to the impurities in the lint. If the impurity content is high, the grade of lint may be reduced. , the lint cleaning machine can be started.
(2) It should depend on the quality requirements of the fabric factory for cotton. At this stage, fabric companiesThe scale and product grades of �� are rapidly extending to both ends, and product varieties are also diversified. Different companies, different product grades and product varieties have different requirements for cotton. This requires the upstream enterprise of fabric production – the ginning mill to also diversify its products.
Generally speaking, the products produced by large enterprises are of higher grade and have complete testing and testing equipment. When purchasing cotton, they focus on the intrinsic quality of cotton. The products of small enterprises are of relatively low grade, with limited testing equipment and higher quality requirements for cotton. Focus on appearance quality and price; ring spinning has higher requirements on cotton grade, length, micronaire, impurities, three filaments, and defects. Open-end spinning has higher requirements on cotton quality due to the spinning principle and the high linear density of spinning yarn. The requirements for various indicators are relatively low; combed yarn has higher requirements for neps and short staple ratio, while carded yarn has lower cotton quality requirements than combed yarn; the cotton used in blended chemical fiber fabric yarn has higher requirements than the cotton used in pure spinning. It should be lower; knitted yarns have higher requirements for cotton than woven yarns; bleached yarns have strict requirements for “three-filament” and oil-stained cotton when choosing cotton, and printing yarns have lower requirements for cotton than other yarns, and dark-dyed yarns The requirements for cotton maturity are very high. If the appearance quality requirements of cotton yarn are high, the lint cleaning machine can be used during the fiber finishing process. If the intrinsic quality requirements of cotton yarn are high, the lint cleaning machine can be used less or not.
2. Strengthen the quality control and management of the entire cotton process
Lint cleaning machines have relatively high technical content, and their manufacturing accuracy and operation requirements are also strict. Therefore, the correct use and maintenance of lint cleaning machines is particularly important. Attention should be paid to the maintenance of cotton cleaning machines, cotton gins and other finishing equipment, to rationally control the output of cotton gins, to avoid the formation of harmful defects, and to strengthen the quality control and management of the entire cotton process.
The three elements of raw cotton grade are maturity, color and ginning quality, which are the three conditions for evaluating raw cotton grade. Maturity and color are the intrinsic qualities of cotton, which are determined by cotton varieties and growth conditions. Lint cleaning The machine cannot change the maturity and color of cotton. It is incorrect to rely solely on the lint cleaning machine to change the appearance to ensure the quality of the ginning process and improve the grade of cotton.
3. Improve the structure of the cleaning machine to reduce damage to lint from the machine structure. Figure 10-4 is the SENTINEL sawtooth lint cleaning machine produced by Rams Company in the United States. Cotton enters the SENTINEL sawtooth lint cleaning machine from the airflow lint cleaning machine. Through the high-speed perforated airflow and the impurity separation roller, the single cotton is directly sent to the sawtooth, and is pulled and combed by the sawtooth roller. The cotton fibers and wool are pulled and combed. When the brush rollers meet, they are blown down by the bristles of the high-speed rotating brush roller, and are sent out through the lint outlet with the help of the wind force of the brush to complete the cleaning work.
Compared with the traditional sawtooth lint cleaning machine, the biggest feature of the SENTINEL sawtooth lint cleaning machine is that it uses high-speed perforated airflow and impurity separation rollers to send single cotton directly to the sawtooth instead of kneading the lint in a ball shape. On a low-speed running cotton collection cylinder, it removes the five rollers (cotton picking roller, cotton pressing roller, drafting roller, drafting roller, and cotton feeding roller) between the dust cage, rack roller, and brush roller. ), reducing mechanical parts, cotton collection and driving parts, greatly reducing damage to lint, and simplifying the feeding procedure, which also facilitates operation and maintenance.
Compared with the traditional sawtooth lint cleaning machine, this method of conveying airflow and dust has another advantage: impurities will not be squeezed into the cotton.
Ginning and cleaning are complementary to each other. Ginning is the basis for ensuring the quality of the ginning process, and cleaning is the supplement and perfection of ginning. If ginning is ignored, the quality of the ginning process will be difficult to guarantee, and if cleaning is lacking, the ginning production efficiency will be difficult to improve.
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