The main reasons for yarn evenness and uneven evenness
1. The evenness of the spinning yarn (line density, linear density uniformity) refers to the degree of change in thickness along the length of the spinning yarn, and can also be expressed as the evenness of the spinning yarn. The quality of fabric products depends to a large extent on the evenness of the yarn threads. The evenness of spinning yarn is divided into short segment unevenness, medium segment unevenness and long segment unevenness. The length of the uneven intervals is 1-10 times the length of the fiber. The uneven intervals are about 1m or less, which is called short segment unevenness. The length of the uneven intervals is 10-100 times the length of the fiber. The intervals are about several meters. The unevenness is called medium segment unevenness; the uneven interval length is 100-3000 times the fiber length, and the uneven interval is about tens of meters, which is called long segment unevenness. When weaving yarn with high unevenness in short segments, there is a high probability that several thick spots or details will be juxtaposed on the cloth surface, which will easily cause fabric defects and have a greater impact on the quality of the cloth. The cloth surface woven from the yarn will have obvious horizontal stripes, which will also have a greater impact on the cloth surface. Relatively speaking, the chance of defects on the cloth surface when weaving yarn with uneven segments is slightly lower, and it depends on the width of the cloth. When certain defects appear, Obvious defects (stripes or cloud spots) will appear when this multiple relationship occurs. Moreover, during the weaving process, it will also lead to an increase in the breakage rate and a decrease in production efficiency. Therefore, the evenness of spinning yarn is an important indicator for evaluating the quality of spinning yarn. 2. The main reasons for uneven spinning lines (1) Differences in fiber properties: The length, fineness, structure and shape of natural fibers are uneven. This unevenness is not only reflected between roots, but also between roots. It manifests itself in different parts of the same fiber; this unevenness of chemical fibers is better than that of natural fibers, but there are still some differences in properties. This uneven nature or difference in performance of the fiber will cause uneven spinning lines, which will be manifested as an increase in the CV value and an increase in the spectrum. (2) Random arrangement of fibers: If the fibers are of equal length and thickness, and the fibers in the spinning thread are straight and parallel, and there are no defects in the spinning equipment and spinning process, the spinning thread will still produce irregularities. Uniform, this is because the number of fibers in the yarn section is randomly distributed. This unevenness is a low limit unevenness, also known as limit unevenness, and can be calculated using Equation (2-11). (3) Unevenness caused by accidental events: This type of unevenness is often caused by unusual reasons, such as flying flowers adhering, gear inlay, traverse guide rod out of position, poor operation, air conditioning failure, marshmallow sticking to the roller, etc. Most of the time, the symptoms are It is the rise of defects or the appearance of very large defects, and sometimes it also appears as mechanical waves.
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