Due to the new technology of dyeing first and then spinning, dyed yarn shortens the process flow of downstream processing enterprises, reduces production costs, has higher added value and other advantages, and is in line with the mainstream development trend of products, but the quality control of dyed yarn is still a A difficult problem before people.
Since dyed yarn has strict quality requirements for raw cotton, the dyeing process must be monitored throughout the entire process, which poses two major difficulties in the production process of dyed yarn. First of all, color spinning has strict requirements on the quality of dyed raw cotton, and the maturity and linear density of dyed raw cotton must be strictly controlled. Because the maturity of dyed raw cotton is closely related to the color rate, the fiber maturity directly determines the color rate. In addition to relatively high maturity requirements, color spinning also requires high linear density of cotton fibers. If the linear density of cotton fiber cannot meet the requirements, the finished fiber will be weak and easily broken, and a large number of neps will be produced during the spinning process. Secondly, color-spun cotton sets higher standards for the content of neps, impurities and third filaments. Neps appear as random fiber knots, which are often not within the main color of the yarn, but determine the main color of the colored fiber. Defects in raw cotton are generally due to poor growth of the raw cotton itself, or during the processing process, poor rolling occurs, resulting in broken seeds or fiber seeds. Broken seeds can be removed during the spinning process, but the same cannot be said for fiber seeds. Therefore, specific processes such as single-mark trial spinning should be used to understand the Uster evenness test data and the number of blackboard defects, troubleshoot similar problems, and select dyed cotton suitable for color spinning. In addition, the three-filament problem will seriously affect the appearance of the fabric or the yarn strength, especially in dark-colored products. Therefore, before dyeing dyed cotton, neps, impurities, and three filaments must be processed in time.
The production operation of dyed yarn is more difficult, which has not changed the trend of rapid development of dyed yarn in recent years. In order to obtain high-quality and stable products, various issues in the color spinning production process must be effectively controlled. Among them, the quality control of the key equipment that constitutes the color spinning production system is particularly important.
As a key part of the color spinning production process, carding equipment plays a particularly obvious role. The carding machine completes carding of fibers through card clothing. Good quality card clothing can not only effectively card the fibers, but also ensure minimal fiber damage, helping to achieve the goal of high production and high quality. Cylinder card clothing can appropriately increase the transverse and longitudinal tooth density, and the rake angle can be appropriately increased to achieve the effect of high-yield carding. The cover card clothing adopts a gradient needle arrangement or a multi-needle area changing arrangement, and uses alloy steel wire. At the same time, increasing the density of needles and reducing the height of needles as appropriate can achieve a more superior anti-bending effect. In addition, in order to make the card clothing smoother and more durable, the strength and elasticity of the base fabric can also be appropriately increased. Doffer card clothing can appropriately increase the tooth pitch, base thickness and tooth depth. As for the tooth tip form, the original linear tooth surface and back shape can be transformed into complex curves, which not only achieves high combing output but also improves transfer efficiency.
The selected rubber roller should have high elasticity to ensure high instantaneous dynamic roundness, long elastic fatigue resistance, and can adapt to light or heavy pressure processes. The rubber roller selected should have low hardness characteristics. Compared with medium- and high-hardness rubber rollers, the probability of uneven holding force of low-hardness rubber rollers is very small, and they are stable and reliable during drafting. At present, the hardness of many rubber rollers with good performance at home and abroad is 63 to 66 degrees. The selected rubber roller should have high wear resistance and no surface treatment. These two characteristics determine the stability of yarn quality, the length of service life and the spinnability. The rubber roller structure selected should be an aluminum liner structure. Throughout the development history of rubber roller structures, it has evolved from differential glue bonding to double-layer or even multi-layer, and then to aluminum liner structures. Generally speaking, aluminum liner structures have significant effects in reducing differences and enhancing stability.
Dyed yarn is a relatively new type of yarn. Knitted fabrics woven using dyed yarn have more harmonious colors, and the fabric surface is natural and uniform. These advantages are not available in ordinary dyeing and finishing products. Therefore, in order to ensure the quality of finished products, quality control of key equipment in the production system must be carried out when producing colored yarn.
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