English Views: 5 Author: Site Editor Publish Time: 2021-12-17 Origin: Site
With the advancement of textile technology, the speed of water jet looms has been continuously increased, and the weaving efficiency has been greatly improved. However, with the increase of weaving speed, it is more difficult to ensure the quality of weaving. Warp willow is a relatively common weaving defect in polyester water jet weaving, and its formation causes are more complicated, and the performance of light and thin fabrics is more obvious. The main reason for the formation of warp willows in polyester filament fabrics is the uneven tension in the quality of raw materials and weaving production, and the state of the equipment also has a certain impact. The existence of warp willows seriously affects the quality of fabrics and the improvement of the economic benefits of enterprises. Therefore, it is of positive significance to explore the causes of warp willows in polyester water jet weaving. On the basis of long-term tracking of the production processes of polyester low-elastic yarn, sizing, water-jet weaving, dyeing and finishing, etc. used by Siyang Chemical Fiber Industrial Cluster Co., Ltd., the causes of warp willow defects and improvement measures are discussed. It is expected to provide a reference for eliminating warp and willow defects in water-jet weaving.
Warp willow refers to the wide or narrow straight strips in the warp direction of the fabric surface, resulting in a difference in color on the surface of the fabric after dyeing, and its distribution may be regular or irregular. Warp willow is a common defect in polyester water jet weaving with complex causes and difficult to solve, which has a negative impact on the quality and economic benefits of polyester filament fabrics produced by related companies. Based on the long-term tracking of the polyester weaving and its products of Siyang Chemical Fiber Industrial Cluster Co., Ltd., this article discusses and summarizes the causes of warp and willow defects in polyester fabrics.
The influencing factors of the raw silk on the warp willow are more complicated, which are mainly reflected in the uneven linear density of the thread, the difference in cross-sectional shape, the number of single fibers in the multifilament, the difference in the content of raw materials, and the different spinning processing conditions. The difference in the linear density of the raw yarn and the fluctuation of the CV value will affect the reflective gloss performance of the raw yarn, and then reflect the difference in the luster of the filament. Fluctuations in the breaking strength of the original yarns will cause the warp yarns to produce wool and broken yarns due to friction during the process of contact with the machine parts; the difference in the elongation performance of the original yarns causes the elongation of the warp yarns to be different, and the tension of the sheet yarns is uneven; the production of original yarns Differences in temperature and process will cause differences in the internal crystalline state of filaments, resulting in increased variation in filament shrinkage in boiling water, uneven shrinkage during fabric dyeing and finishing, resulting in uneven cloth surface; unstable oil content of filaments will cause warp tension fluctuations , The warp yarn is prone to entanglement during warping, and static electricity accumulates due to friction during the production process, which will eventually cause warp defects on the fabric surface.
Warping aspect During the warping process, a certain tension must be applied to the warp to ensure the normal weaving. The fluctuation of warp tension will cause inconsistent warp elongation and deformation, and warp refraction will be different. When the processing tension is removed, the elastic deformation and recovery of the warp yarns are different, resulting in a difference in the elongation of the warp yarns, which will affect the absorption of the dye liquor by the fabric during the dyeing and finishing process, and warp willows are formed on the cloth surface. The main factors that cause warp tension fluctuations: a) The difference in the size of the bobbins of the warping creel in the warping process, the unreasonable placement of the bobbins, and the unclear thread path will lead to different unwinding tensions; b) the angle of the warping fan is incorrect , The warp yarn is subjected to different friction; the number of threadings changes or the fixed width reed is threaded incorrectly during the warping process, resulting in uneven warp surface tension; c) the warping machine tension compensator is in poor condition and the warp tension difference is too large.
3. Sizing aspect
During the sizing process, the unwinding tension of the warp beam is fluctuated in the unwinding zone, the warp between the sizing roller and the drag roll is too elongated, the drying temperature is unstable, and the warp is too loose and bonded, the surface of the sizing roller is damaged, and the speed fluctuations, etc. Factors will cause uneven warp tension in the sizing process. There are messy wires, oil stains and other debris on the mesh cover. Failure to clean up and block the air inlet in time will cause the hot airflow to be unsmooth, the air intake of the drying room deviates from the set value, and the operator does not deal with it in time. Willow produced.
4. Parallel axis
When FDY is used in the warp of polyester filament fabrics, warp will be easily generated at the head and tail of the weaving shaft, and it cannot be eliminated by adjusting the water jet loom process, which seriously affects the weaving efficiency of the enterprise. Through the author's long-term tracking and analysis of the weaving of this variety, it is found that the number of parallel shafts is related to the occurrence of head and tail warp willow defects, and the structure of the shaft holder of the parallel shaft will also have a certain impact on the head and tail warp willows. The warp yarn is passively unwinded from the paralleling machine, and the creel relies on the tension sensor to adjust its braking force. Due to the difference in the friction factor between the braking system and the paddle shaft between the various shafts, the tension between the various shafts is different. . At the same time, during the parking process of the paralleling machine, the tension of each axis of the paralleling machine is also inconsistent, which eventually causes the fabric to have warp defects.
5. Weaving
The warp and weft density and organizational structure design of polyester fabrics are unreasonable, and the fabrics are too tight and too dense, which will increase the probability of warp willows. Both will increase the probability of producing warp willow. Among them, plain weave fabrics are the most obvious, followed by twill weave fabrics, and satin weave fabrics are the smallest. In the weaving process, if the tension of the warp surface is too large or too small, it will cause the warp tension difference; in the weaving process, the improper design of the weaving speed, opening amount, and crimping speed may cause warp willows.
6. Dyeing and finishing
The desizing of polyester yarn is unavoidable, and the alkali reduction is uneven, which will affect the coloring of the slurry; damage to the surface of the polyester yarn results in different absorption of the dye solution, difference in dyeing performance, and affects the uniformity of dyeing, resulting in warp of the dyed fabric. willow.
1. Raw silk use management
The company has 32 texturing machines, most of the raw materials needed for polyester weaving are self-supplied. Ensuring the quality of DTY requires strict self-inspection, mutual inspection, and special inspection from the first process of bombing. The company uses an advanced online tension monitoring system in the raw material production process, which can detect bad raw yarn in time, prevent improper operation and technology, and separate poor quality raw yarn in time, prevent improper operation and technology, and separate in time Produce the finished yarn with quality problems to improve the overall quality of the yarn. Set strict BC-grade product parameters, identify and isolate the graded yarns. After doffing, the operators strictly follow the self-inspection process to avoid appearance defects (such as netting, poor molding, wool, stiff yarn, etc.) from flowing into the next process . In the inspection process, each upper and lower process is checked layer by layer, and a strict reward and penalty assessment system is formulated. According to the requirements of different fabrics, select the appropriate type and quality of the raw silk, check the origin and batch number of the raw silk before leaving the warehouse, eliminate the size difference and poorly formed packages, and avoid the mixing of different batches of raw materials; and do it before the machine Good inspection of raw silk. Control the error of the titanium dioxide content of the silk thread within the range of 0.05%, and perform the cloth head dyeing sample before weaving. If there is a problem with the dyeing, the original silk should be tested and adjusted accordingly.
2. Warping process
The warp tension control in the warping process has a great influence on the weaving quality, so it is very important to ensure that the winding tension of each warp during the warping process is uniform and moderate. It is necessary to maintain a unified and reasonable warping tension so that the warp yarn winding process is arranged neatly, so that the warp beam has the appropriate winding strength for the next process unwinding. If the warp beam winding strength is too low, the warp unwinding process will be unbalanced, resulting in unstable sheet yarn tension, resulting in warp willow and warp breakage. The correct thread path and proper tension can be used to maintain uniform and stable winding tension and avoid poor unwinding in subsequent processing due to unstable tension. In view of the factors that may have a greater impact on the quality of weaving, the company has formulated the following specific measures.
A) Sectional warping. The first coil of each batch of warp yarns must be carefully checked for the appearance of the network wool yarn before drawing. At the same time, the quality of the raw materials should be checked when the bottom layer is changed to the small tube to determine whether the quality meets the replacement requirements. The warp unwinding process takes into account the twist direction of the warp yarn, and the unwinding direction remains the same as the twist direction of the yarn. The unwinding direction of the strong twist yarn is the direction in which the warp yarn is not easy to generate torque.
B) Strengthen the management of drawing-in reeds. Fabrics with a square meter mass of less than 60g are likely to cause reeds and warp willows. Good quality steel reeds should be selected, and feedback on the problem of warping raw materials should be required. If it is a problem of raw materials, only rewards are not penalized. In the face of quality problems of split warping, rewards and punishments must be given.
C) The tension adjustment of the creel. Divide into three major areas: upper, middle, lower, front, middle and back for adjustment. The tension in the rear upper and lower zones is the largest and therefore the smallest tension ring is used, followed by the upper and lower tension in the rear middle and middle zones. As the size of the bobbin changes, the unwinding tension of the thread also changes. The following optimizations are made for this process: i) The fixed-width reed displacement is increased by 0.05mm after each warp is drawn, and the reed is drawn on this basis. Add 0.05mm displacement to ensure that the unwinding tension of each batch of warp beams is consistent; ii) If the above adjustments are made, there is still a loose warp on the top side. When the author sets the process of each width, the width of the reed is wider than that of the normal loom 2～3cm; iii) For more stable varieties, take warp dislocation. For example, there are 800 bobbins in our company, 400 are symmetrical, and the tension is parabolic. This will cause the tension of the side cloth to be too small, and the phenomenon of loosening at the top can not be solved. Now we divide the first one into two. Pull 400 bobbins in the back zone, and then pull 400 bobbins in the front zone, so that the tension presents a symmetrical U-shaped distribution, which completely solves the problem of loose top edge in weaving.
3. Sizing process
Strictly control the warp tension to make the warp tension meet the technological requirements to ensure the smooth progress of the sizing process and the winding process. The sizing process design determines the reasonable sizing speed, slurry concentration and drying temperature according to the different raw materials and the total number of warps. The drying degree of the warp after passing through the drying chamber is required to be about 80%. Appropriate air volume should be determined according to different sizing types, and the air inlet and outlet mesh cover should be cleaned regularly during the production process to ensure that the mesh cover is free of messy wire, oil, etc., to prevent clogging and ensure unobstructed hot air. Polyester yarn has a high initial modulus and is not easy to deform under a small load. The warp yarn is subjected to a large load during the sizing process. Therefore, it needs to be placed for a period of time after the raw material is wound to form, so that the elongation generated by the warp yarn processing can be fully recovered. Reduce the warp difference between different warp beams and warp pieces.
4. Parallel process
Uneven warp tension in the parallel axis, uneven bottoming, magnetic powder quality, and uneven thread arrangement may all cause warp willows. For the double-layer warp beam frame, the drawing directions of the warp threads on the upper and lower layers of the pulp shaft are opposite, and the warp threads on both sides of the pulp shaft can be mixed and arranged to avoid the concentration of the defect warp threads and reduce the warp willow generation from the visual perspective. The setting of the taper tension and taper angle of the parallel shaft should be reasonable; check the status of the magnetic powder regularly, and replace it in time if the magnetic powder deteriorates. Reed reed correction is carried out when reed is pierced, and the number of warp threads per reed tooth corresponds to the number of pulp shafts to ensure that the telescopic reed gap is uniform and the warp threads are arranged neatly. At the same time, the temperature and humidity in the production process are controlled to avoid warp tension fluctuations caused by static electricity.
Strengthen the inspection and maintenance of the main components of the paralleling machine, such as the paralleling shaft frame, the shaft, the brake, etc., and replace the parts in time when they are worn to ensure the normal operation of the equipment. Each brake should be equipped with a tension sensor to monitor the unwinding tension in real time to eliminate the influence of the start and stop of each axis on the warp tension fluctuation. The unwinding method is improved. Each axle frame is replaced with a variable frequency motor, and each axle is changed from passive unwinding to active unwinding. The speed of the paralleling machine is adjusted synchronously according to the change of unwinding tension to further reduce the tension difference between the warp threads on each axis.
5. Weaving process
The weaving process may not necessarily be reasonable, so that the jet water stream has good clustering and the nozzle direction is accurate, so as to avoid the water stream contacting the warp yarns and causing warp yarn tension fluctuations. Reduce the heddle density as much as possible. Practice has found that it is more appropriate to control the heddle density at 8-10 pieces/cm. Too high density will cause too much friction, so it is necessary to reduce the heddle density as much as possible. Strengthen equipment inspection and maintenance efforts to ensure that the water jet loom is clean and tidy, and the sley is free of slurry blocks. Regular inspections of heald joints and steel reeds are carried out, and problems are solved in time. Strengthen the technical training of operators, improve operating skills, and implement an assessment system to improve employees' sense of responsibility, and avoid human-induced degradation of weaving quality.
Our company mainly uses plastic healds, which are easy to swing. It is easy to cause warp and willow defects on light fabrics. By increasing the density of the healds, the healds are prevented from swinging and bending, and the plastic heddle holes are prevented from jamming the warp, and the warp warp is avoided. After weaving the upper shaft, feedback the problem of raw materials in time, implement it to the previous process, and improve the sense of responsibility of the previous process. For the color warp that seriously affects the quality, take a 10cm cloth strip for dyeing inspection after each pan head is turned on normally, and if there is any abnormality, it will be removed in time to avoid causing losses to the company.
6. Dyeing process
Before dyeing and finishing, the warp yarn needs to be desizing thoroughly to avoid coloring the warp yarn slurry; select dyes with good levelling properties, and add a leveling agent during the dyeing process to ensure that the dye molecules enter the fiber evenly.
