Abstract: The “warp hanging” defects of worsted wool fabrics are divided into three categories: single continuous piece hanging warp, single scattered warp hanging, and double scattered warp hanging, and these types of “hanging warp” are analyzed respectively. “The causes of defects and corresponding preventive measures and corrective methods are proposed.
Keywords: Dispersed drop warp; yarn hairiness; yarn winding
In recent years, with the continuous updating of production equipment and production technology, the overall quality level of my country’s worsted woolen fabrics has been significantly improved. Improvement, various defects have also been significantly reduced. However, with the application of new equipment such as shuttleless looms, the common defect of “warp hanging” has not only increased but not decreased, and has evolved into one of the main defects affecting the quality improvement of worsted woolen fabrics. Therefore, based on the actual production conditions, we conducted a relatively in-depth investigation, analysis and research on this defect, took corresponding measures, and achieved certain results, effectively curbing the increase in “diaojing” defects, as discussed below.
1. Overview of “Drop Warp” Defects
“Drop Warp” refers to defects in the fabric structure caused by single or multiple warp yarns being hung tightly. When inspecting finished products, they can be identified visually and by touch.
Visual inspection – obvious color depth can be seen at the “hanging warp”, and sudden bending of the weft yarns can be seen on fabrics with clear weft yarn arrangement such as grids;
Hand mold – at the “hanging warp” The tightness of the warp yarns can be clearly felt.
Therefore, in general, “warp hanging” is a defect that is exposed after dyeing and finishing due to inconsistent residual tension of the warp yarns in the blank. The root cause of “hanging warp” should be in the spinning and weaving process.
2. Classification and causes of “warp hanging” defects
2.1 Classification of “warp hanging” defects
In-depth analysis found that in the textile process, there are many factors that produce “warp hanging”. In order to facilitate analysis and research, according to the different manifestations and formation mechanisms of “warp hanging” defects on the fabric during finished product inspection, “warp hanging” defects can be divided into the following three categories.
①Single continuous warp hanging: The length of the “hanging warp” is usually more than 10m, and its distribution pattern is mainly single, and occasionally there are multiple warps. The characteristic is that adjacent warp yarns generally do not have a “hanging warp” phenomenon.
②Single scattered hanging warp: The length of the “hanging warp” is usually less than 1m, and the entire length of the warp is scattered irregularly and intermittently. There is generally no “hanging warp” phenomenon in adjacent warp yarns.
③Double scattered warp hanging: This type of defect on the weave surface manifests itself as two adjacent warp yarns “hanging warp” at the same time with the same starting and ending points. The length of the “hanging warp” is usually 0. Below 5m. Its distribution pattern is also irregular and intermittent throughout the whole length. It is particularly prominent when shuttleless looms are weaving at high speeds. It is a new type of quality defect that appears after the use of shuttleless looms.
2.2 Causes of various types of “drop warp” defects
2.2.1 Single continuous warp drop
This type of defect is caused by the warp yarn being continuously dropped during the warping or weaving process.Caused by unexpected tension.
① Warping process: During warping, the warp process channel is blocked by debris such as fly flakes, number paper, broken yarns, etc., causing the tension of a certain warp to increase abnormally. If the operator does not clean and inspect in time, an accident may occur. The probability is higher.
②Weaving process: During weaving, the warp yarn process channel is blocked by debris such as flying flowers, number paper, broken yarn, etc., and the tension of the yarn is too high. Since the warp yarn is constantly displaced during weaving, this situation is generally not easy to occur. .
2.2.2 Single scattered warp drop
This type of defect is caused by intermittent and unexpected tension on the warp yarn during the spinning and steaming process, or caused by uneven moisture return of the yarn. The yarn stretches and shrinks unevenly. There are mainly the following operations and processes that can easily cause this kind of “suspended sutra”.
①Joining operation: After the yarn is broken due to accidental tension, the damaged yarn at both ends is not removed and the yarn is spliced directly.
② Unwinding operation: When the yarn is unwinding, intermittent and unexpected tension may occur due to poor bobbin formation or incorrect placement.
③ Yarn steaming process: During the yarn steaming process, the top of the bobbin is not covered with protective felt or contacts the tank wall. The yarn on the bobbin is unevenly dampened due to condensation and dripping water in the tank, and the yarn steaming equipment is poor or improperly operated, resulting in Condensation and moisture occur on the surface of the yarn.
2.2.3 Double scattered warp drop
This type of defect is caused by the warp yarns being entangled with each other and unable to open normally during the weaving process, causing the adjacent yarns to be accidentally tensioned. It consists of adjacent yarns entangled with each other, and ends when the yarn is broken or separated when opening. The reasons for the entanglement of adjacent yarns during weaving can be mainly analyzed from the following five aspects:
①Due to poor cleaning work and abnormal workshop temperature and humidity in the spinning process, there are many flying flowers and excessive yarn hairiness;
② The double-twisting speed is too high, causing the yarn hairiness to be too long;
③Steamed yarn Insufficient shaping and large yarn twist;
④Improper selection of weaving shed form causes serious friction when adjacent yarns open, and improper adjustment of the stopper device causes friction and fuzzing of adjacent yarns;
⑤Warping When reversing the shaft, the amount of wax applied is too little or the quality of the liquid wax is poor, and the coating effect of the liquid wax on the yarn is poor.
In short, the causes of “drop warp” defects can be summarized as the following six points: abnormal yarn process channel; improper selection of process parameters and mechanical adjustment on the weaving machine; long yarn hairiness; insufficient yarn shaping and insufficient moisture regain. uniform; improper joint operation; poor coating effect of liquid wax on yarn.
3. Prevention and correction of “warp hanging” defects
3.1 Preventive measures
① The spinning and weaving departments should strengthen the inspection of the yarn process channel, discover problems in time and deal with them in a timely manner to ensure the process The channel is clear and normal.
② Attach great importance to the yarn steaming process, standardize the equipment, process, and operation management of steamed yarn to ensure the yarn setting effect (the number of twists is less than 15), and strictly prevent the yarn from being unevenly dampened.
③Attach great importance to the problem of yarn hairiness and strengthen the understanding of process, equipment, operation and temperature and humidity.In terms of quality control management, yarn oiling and other processes are used to strive to reduce yarn hairiness.
④ Standardize joint operations to reduce artificial “hanging”.
⑤ Pay attention to the waxing process and liquid wax quality, and reasonably control the amount of waxing on the inverted shaft to ensure uniform waxing. In addition, attention should be paid to the technical transformation of the waxing device, and efforts should be made to improve the coating effect of liquid wax on yarn hairiness. If necessary, the cold sizing process or sizing process can be used.
⑥ Reasonably formulate the weaving drawing-in method, reasonably select the shed form of the loom, optimize the adjustment of process components such as the warp stop frame, and strive to reduce the friction of the yarn during the weaving process.
3.2 Corrective measures
Once the “suspended warp” defects are formed, they are generally difficult to remedy in subsequent processes. In the actual production process, the following compensation methods are mainly used, and certain results have been achieved.
①Repair and change yarn, that is, pull out the “hanging warp” yarn, replenish it with normal yarn, and then finish it through processes such as washing, boiling, and steaming. This method has a better compensation effect, but it is only suitable for a single continuous warp lifting, is time-consuming and labor-intensive, and seriously affects the production schedule.
②High-temperature treatment, that is, the fabric is treated at high temperature in the dye vat, and then shaped through processes such as cooking and steaming. High-temperature treatment (above 80°C) can open the chemical bonds of wool fibers and rearrange them, so it can compensate for the “warp hanging” defect to a certain extent. This method can compensate for a single continuous scattered hanging warp, but the compensation effect for double scattered hanging warps (the degree of “hanging warp” is generally more serious) is poor, and has a greater impact on the color, lightness, strength, etc. of the fabric. , has certain limitations.
To sum up, the “drop warp” defect is manifested in the finished product, formed in weaving, and has its root cause in spinning. It is a highly concealed defect and has complex influencing factors. Therefore, preventing the occurrence of “Diao Jing” defects is a systematic process, which must focus on prevention, check every step, and start from the front. Efforts should be made to eliminate the root causes of defects by strengthening process control and standardizing process operation management.
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