Due to problems such as thick details and uneven twist in the yarn, there will be some fragments with less strength in the yarn, causing the potential risk of yarn breakage, which is called “yarn strength weak loop”. The existence of yarn strength weak loop is one of the key factors restricting the speed of spinning machine. The reason why strong weak loops appear on the yarn is mainly due to the existence of detailed and fragmentary weak twists in the yarn.
The strength characteristics of raw yarn include average strength, strength unevenness, average elongation and elongation unevenness. Generally, the average strength of warp yarns is 15cN/tex, and the strength unevenness is about 9% to 10%. The average strength of weft yarns is 12cN/tex, and the strength unevenness is about 9% to 10%. The average elongation at break is generally controlled within 2%.
The dangers of strong and weak links
The strong weak loop generally refers to the lowest strength of the yarn. An important strength indicator for the stop of the air-jet loom is the strong weak loop. It is generally believed that when the yarn fineness is only 40% of the normal yarn, such detailed weak loops will inevitably cause end breakage. If the strong weak link is at 4cN/tex and the elongation is less than 2%, it will inevitably cause breakage.
In addition to detailed defects in other strong and weak links, which account for 61%, other strong and weak links such as weak twists, poor joints, and thick sections can also cause stops between longitude and latitude, accounting for about 39%.
In addition to average strength and uneven strength, the strong factors that cause warp and weft yarns to stop are strong and weak loops. Japanese businessmen go to China to buy yarn, especially the number of strong and weak loops of 100,000 wefts. The possibility of yarn purchase is judged based on the 100,000 weft breakage detected by the high-speed and large-capacity strength machine tensogiet. Therefore, in the strength requirements of yarns in considerable scale knitting and weaving factories, special emphasis should be placed on the level of strength and weak links. Some related enterprises in my country A tensogiet strength tester should be equipped as much as possible to control the quality of raw yarn.
Causes and solutions of strong and weak loops
There are three main types of details on the raw yarn: one is short velvet details, one is thick details at the knot, and the other is long details or multiple short details connected together will cause breakage.
In order to reduce strong weak links and provide good raw yarn for downstream processes, corresponding measures must be taken, such as the use of a new roving frame with four-unit transmission and four-roller drafting. On the one hand, it eliminates the details caused by the switch car, and on the other hand, it improves When drafting the sliver, it is necessary to reduce coarse and detailed defects, etc. It is also necessary to strengthen the coordination of the transmission teeth and keys of the drafting part to prevent loosening gaps and ensure the synchronization of the drafting process. This is also one of the important methods to reduce details.
In addition, rational configuration of the process and selection of good drafting components, such as rubber rollers, rubber rings, upper and lower pins, and pressure mechanisms, are also factors that reduce details.
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