The evenness CVb of pure cotton combed high-count compact spinning yarn is the main factor affecting the yarn quality level, weaving and warping ends, and the fabric style (especially the high-count and high-density fabric style). Spinning yarn evenness CVb is mainly controlled from three aspects: pre-spinning technology and quality, spinning technology and quality, and spinning equipment and daily operation management.
01 Pre-spinning process and quality control
The quality of semi-finished products is an important factor affecting A major factor in yarn evenness and evenness CVb value. The focus of semi-finished product quality control is the short staple rate, evenness CV value, and occasional yarn defects and mechanical waves in each process.
Based on the cotton distribution situation, we have formulated strict quality control standards for semi-finished products. The main control indicators are shown in Table 1.
Table 1 Semi-finished product quality control standards
The CV value and short staple rate of semi-finished products will directly affect the yarn evenness CV value, while mechanical waves and occasional yarn defects will directly lead to the deterioration of yarn dryness CVb. Therefore, it is necessary to strictly formulate the test cycle and test items for pre-spinning, and establish a relevant evaluation system to prevent unqualified semi-finished products from flowing into the next process.
The roving process must follow the control principles of heavy weight, medium pressure, and large twist coefficient. Under the condition of ensuring normal production of spun yarns, the roving basis weight and roving twist coefficient should be appropriately increased, and the roving pressure and roving draft distribution should be reasonably set to ensure the even CV value of the roving and prevent the generation of mechanical waves in the roving. In terms of quality control, test cycles for roving front and rear row elongation, roving evenness CVb, roving twist, etc. are formulated to ensure the stability of roving quality indicators.
In terms of equipment management, establish a strict equipment management system to ensure the operating status of the equipment and eliminate backward and abnormal machines. According to test statistics, there are 10% neps and short lint rates behind the machine in the blowing and carding process, which will lead to the deterioration of the overall neps and short lint in the carding process and the deterioration of the yarn quality indicators. Therefore, all processes must eliminate lagging machines. , to ensure the stability of semi-finished product quality indicators.
In terms of operation management, we strictly implement the cleaning schedule and standardize operating methods. According to test statistics, if the pre-spinning is well cleaned, the number of defects cut per 100,000 meters of winding can be reduced by about 50%.
02 Spinning process and quality control
Spinning process process and quality The key to control is to reduce the difference between spindles, ensure the consistency of equipment operation, ensure the consistency of the process on the machine, and achieve reasonable distribution of spinning draft. The spinning machine, the same type of spinning cradle pressure, the front punch of the rubber roller before spinning, the size of the spinning floating area, and the spinning distance block (pressure rod) must be consistent, including the diameter of the rubber roller, usage time, manufacturer, and rubber roller The hardness, usage time of mesh rings, mesh number of mesh rings, manufacturer, rubber ring thickness, etc. must be consistent.
03 Daily management of spinning equipment and operations
3.1 Daily management of spinning equipment Management
Do a good job in daily maintenance of spinning equipment to ensure the healthy operation of the equipment. Pay special attention to components such as unwinding, drafting, and twisting. The first thing is to ensure the consistency of the unwinding parts of the spun yarn, the rotation of the hanging spindle should be flexible, and the position of the yarn guide rod should be consistent to prevent accidental drafting of the roving. Second, do a good job in lubrication of the equipment to reduce the generation of mechanical waves and draft waves. Third, strengthen the quality inspection of the flat wiper, prevent missing or wrong replacement when replacing the wire ring, and eliminate problems such as hanging the wire ring, burning out the operation, etc. Fourth, the focus of the twisting part is to reduce uneven twisting and uneven twisting. uniformly controlled within 3.5%.
3.2 Daily management of spinning operation
Key points of daily management of spinning operation It is guaranteed to be in a clean and tidy condition. Occasional yarn defects in spun yarns are one of the main causes of abnormal CVb in spun yarns. In addition to unreasonable process settings and poor equipment operation, spun yarns are also caused by malfunctioning parts and poor equipment cleaning. One of the main causes of yarn defects. Therefore, in daily operations, a complete operating cleaning cycle and inspection system must be established to ensure the good operation of the traveling cleaner and the cleanliness of the spinning drafting area. At the same time, a complete 24-hour dynamic inspection system for special parts has been established to ensure that the mesh ring, rubber roller, and rubber ring operate normally 24 hours a day, thereby reducing the deterioration of evenness CVb caused by occasional yarn defects.
Through the above measures, factors that cause the deterioration of CVb of spun yarn evenness are eliminated, ensuring the stability of the CV value of spun yarn evenness and eliminating differences between spindles. production, thereby ensuring that the CVb of the spun yarn is controlled within a good range, so that the quality of the yarn can meet good cloth surface effects and customer requirements. </p
