Reasonable Setting Of Process Parameters To Control Viscose Yarn Details

With the continuous improvement of market demand for textile quality, the upgrading of textile fabrics has become a new breakthrough in the development of China's textile industry, and the requirements for yarn quality are also more stringent. The details of yarn are very important factors in yarn quality. Production practice has proved that the details of spinning have great influence on the breakage of spinning ends, weaving and knitting. Judging from the current market situation, viscose yarns are mainly used for knitting yarns to interweave with filaments, and their requirements for yarn details are more and more stringent. How can we control the details of viscose yarns by setting technological parameters reasonably? Look down

Reasonable use of flowers and cotton to control the content of lint.

The control of short fiber in raw materials is the first way to reduce the details of yarn. As a kind of chemical fiber, viscose fiber is different from cotton. It usually contains only a small amount of hardened silk, silk, rubber block and super long fiber. The length of the viscose fiber is better and the short fiber content is very small. Therefore, it is not necessary to consider the amount of short fiber content when making the matching. However, in order to take account of the production cost, it is inevitable to use flower back and reuse cotton, and the quality of returning flowers and cotton is different. Generally speaking, the use of cotton short cotton can be properly recycled, and the suction cotton, chopper flowers and so on not only mixed more, and contains a lot of short pile, must be treated after a small amount of reuse, the proportion can not generally exceed 2%.

Reasonable disposal of carding process, reduction of fiber damage and reinforcement of short pile

Because viscose fiber is free from impurities and fluffy, with only a few defects and strong and low, so the opening and cleaning process is carried out in accordance with the principle of "combing, beating, combing and beating, using less striking methods and improving the form of the driver, and strengthening the elimination of short fibers". In order to exclude the short pile, it can increase the suction capacity of the cage and increase it to about 1400 r/min. In addition, it is necessary to strengthen the testing of mechanical properties and short fiber for holding and blow down cotton, and measure the short fiber after the change of raw material is bigger or the machine is maintained, and adjust the technological parameters in time, so that the growth rate of short fiber can be controlled within the prescribed range.

The key parts to lighten the fiber damage in the carding process are the cotton and the roller. According to different fiber lengths, different lengths should be applied to the process parameters of cotton face and back. Practice has proved that viscose fiber roller speed is generally below 850 r/min, otherwise fiber damage intensified. The working length of the cotton plate is generally 32 mm, and the diamond can be used for cotton roller. The key to carding and removing short staple is the covering of flowers and the noil of the rear cart. The distance between the upper and the upper cover plates can be appropriately increased, the speed of the cover plate should be increased, and the gap between the bottom and the inlet should be reduced. As far as possible, the dedusting knife can be cut off as low as possible under the premise of high knife and large angle, which can effectively reduce the short staple rate. However, due to the low content of viscose fiber short, in order to save raw materials and reduce the cost, the process must be properly taken into account. In short, the growth rate of short fiber in the combing process of viscose fiber should be controlled within 1.5%.

The internal structure of semi-finished products can be improved by using fiber straightening technology.

Production practice has proved that the internal quality of roving, the parallelism of fiber elongation, the degree of separation and the short fiber percentage have great influence on the yarn evenness CV value, especially the detail of yarn. Generally speaking, the straightness of fibers is small, and the effective length in the draft area becomes shorter, so that the floating process increases, fibers tend to tangle, produce cluster motion, destroy movement rules, and generate thick and thin sections. Fiber separation is small, small cotton bundles and neps in fiber are increased. Due to the large cohesive force of small cotton bundles, it is also easy to beam movement and produce coarse and detailed details. Therefore, rough process must adopt the straightening process to improve the structure of semi-finished products.

According to the theory of cotton spinning technology, the correct process of 1.5D * 38 mm viscose fiber is 8 times the total draft and 1.7 to 1.8 times of the draft area, 48 mm, two and 1.10 to 1.30 times. If the roving does not cause accidental elongation, it is necessary to use proper tension spinning to ensure that the yarn has a certain degree of tightness. The draft in the back area is usually about 1.10 to 1.20. Production practice has proved that this process configuration has great effect on improving the fiber straightening state, and can reduce the details of yarn.

Reasonable selection of drafting process and strengthening of short fiber control

Due to the limited ability to remove short fiber from the carding process, the three drawing processes of drawing, roving and spinning must be reasonably allocated to the friction field in the drafting area to enhance the control of floating fibers. Especially in spinning process, doing "strong control" is very helpful to improve yarn quality and reduce coarse details. However, due to the long viscose fiber and great resistance to friction, it is necessary to seriously explore the technical parameters of "strong control" and what effect it will put to the best. ""

Properly increase roving twist factor

After twisting drafting in the back of the spinning area, more twist is retained into the front area, which strengthens the control of the friction zone in the front area, thus increasing the control ability of the front area to the floating fibers. But the roving twist factor is not as big as possible. Comprehensive consideration should be given to the factors such as the performance of the spinning drafting, especially the performance of the old machine, the quality of the semi-finished products, the drafting ratio of the back area of the spinning area, and the center distance between the rear rollers and so on. The upper limit of twisting coefficient should be increased as the standard of spinning not hard. Viscose roving twist coefficient is generally controlled between 65~78. ""

Selection of small draft back zone drafting

The main function of the spinning back zone is to prepare for the front zone, so that the yarn in the front area is evenly distributed and the necessary tightness is matched with the friction zone in the front area to form a stable distribution of the front friction area, so as to give full play to the role of the leather ring controlling the movement of the fibers, thereby reducing the coarse details of the yarn and improving the appearance quality of the gauze. Smaller draft area drafting can reduce draft unevenness and proper use of roving twist to increase the tightness of draft yarn in the back area and the front zone, which is conducive to the control of fiber movement in the back area, and also helps to exert the role of the front apron to control the movement of the fibers, and to concentrate the front zone drafting so as to improve the details and evenness of the yarn. But the draft in the back area should not be too small, otherwise it will appear the phenomenon of gushing, but it will deteriorate the evenness and increase the thickness. It is worth noting that the smaller rear area drafting must be matched with the larger rear spacer, which is beneficial to meet the requirement that the pulling force is less than the grip force. For viscose fibers, the draft in the back area is generally less than 1.25. ""

Improving the pre spinning process

The low roller and high strength rubber roller is used for spinning the front roller. The low hardness and high strength rubber cots are deformed under high pressure, and the larger surface of the circular arc can be formed on the surface of the lower roller. That is to increase the effective contact area of the fiber. In fact, it reduces the middle floating area, and controls the fiber more effectively, thus improving the evenness and reducing the details of the yarn. Production practice has proved that the use of low hardness and high strength cots can improve the evenness of 0.5% and reduce the details. But in the use of viscose varieties, we must pay attention to choosing the right hardness and accurately grasp the exchange cycle, otherwise it will backfire.

The central friction field is reasonably distributed. The matching selection of the upper and lower leather rings is a prerequisite for strengthening the control of the friction force in the middle part. Generally, the matching principle of the upper Panasonic tight and the thin upper and lower thick leather aprons is good, and the elasticity and softness of the leather aprons are good, so that the upper and lower leather rings are tightly and without gaps in the rotation. On the pin selection, the upper pin selects the carbon upper pin and the lower pin can choose the new T type lower pin. The new T type lower pin has improved the upper surface shape of the lower apron of the apron, strengthened the control force of the upper and lower aprons to the fibers, and made the distribution of the friction field more reasonable. With this configuration, the drafting ability of the apron is greatly improved, the ability to control the bar is increased, the floating condition of the floating fiber is improved, the speed of the fiber is stable, the yarn thickness is uniform, the coarse section and the detail are obviously reduced, and the CV value is reduced. However, for viscose fiber, due to the special properties of fiber, the location of the new top pin position is most suitable. It needs to be optimized through repeated tests. At the same time, it must also be highly qualified for installation.

Reasonable allocation of other process parameters to reduce accidental drafting

Rough draft is the main reason for yarn growth. In the process configuration, it mainly involves the formulation of tension parameters. Generally speaking, the principle of partial tension of guide bar is that it is advisable to have small control when no surge occurs. If the tension is too large and the machine is broken, it will produce long details when the driver is bad at handling. The roving tension teeth are properly configured so as to avoid frequent tension teeth and produce unevenness of tension. In addition, without increasing the yarn evenness, increasing the weight of the sliver can increase the cohesion of the fiber. If the weight is too light, the fiber holding capacity is not enough, and the unexpected draft will intensify when the roving guide bar is used. In addition, the small diameter of the compression bell can also increase the holding force of the cooked strips and reduce the unexpected draft during drafting.

Reducing details is a highly technical work involving many aspects. In particular, the properties of viscose fiber are different from that of cotton. Therefore, it is necessary to analyze the details of viscose fiber yarns in detail, and to grasp the main contradiction according to the characteristics of fibers, so as to make the details of the yarn in a controlled state.