Some quality issues in spinning, such as hairiness, neps, foreign fibers, strong weak links and immature fiber content percentage, are important issues that directly affect yarn quality, even fabric quality and the production efficiency of downstream processes. We should attach great importance to it, set up defenses one by one, and use various high-tech testing instruments to monitor and solve the above problems online and offline. At least we can detect problems in time and take measures to reduce the quality problems found. In order to further improve the spinning quality.
Neps
The harmfulness of neps
The number of neps in the yarn not only affects the appearance quality of the yarn and gray fabric, but also directly affects the dyeing effect of the fabric, causing dyeing defects. As people have higher and higher requirements for the appearance quality of textiles, neps have become Defects classified as important controls
The formation and distribution of neps
(1) There are many harvesting methods during cotton harvest that will produce neps and impurities in the raw cotton. Currently, harvesting methods are roughly divided into manual harvesting and mechanical harvesting methods. Foreign manual harvesting methods are mainly used to pick long-staple cotton and fine-staple cotton. Otherwise, all harvesting methods are Mechanical harvesting is the main method. Mechanical harvesting brings a large amount of impurities to the lint, and even a small amount of neps, which makes it difficult for the ginning factory to remove the impurities. It also causes a certain number of neps in the raw cotton after ginning.
(2) In the production of blowroom cotton, there is a contradiction between removing impurities in raw cotton and increasing neps and short lint. The faster the beaters in each department of blowroom cotton are, the better the impurities are removed. The longer the process of the blowroom cotton production line is, the more neps will be increased. Therefore, we should strive to shorten the process of the blowroom cotton production line, optimize the process technology of impurity removal and neps, and strive to minimize the increase of neps and short lint in the blowroom cotton.
(3) The greater the proportion of immature fibers in raw cotton, the greater the chance of producing neps and short lint. Before raw cotton enters the blowroom cotton production line, we strive to control the distribution of immature fibers and reduce the proportion and difference of immature fibers in the mixed cotton.
(4) The carding machine is the main process for reducing neps. Many neps can be carded or eliminated on the carding machine. Therefore, the carding machine must be fast and accurate to strengthen carding. In particular, the carding function between the cover plate and the cylinder should be strengthened. The new carding machine is equipped with a fixed cover plate, which improves the impurity removal function and carding effect of the cotton feeding part. These are very important for reducing neps. .
(5) Online and offline monitoring and control of neps in raw cotton to control the increase in the number of neps in production. The AFis raw cotton property detector can be used to check the percentage of immature fibers in raw cotton and the percentage of immature fibers in raw cotton package by package. The total amount of neps must be discarded if it exceeds the specified index, so that the number of neps in each process of blowroom and carding can be controlled. New carding machines such as DK803, DK903, DC03 etc. can also detect the dynamic changes of neps online, alarm according to the increase of neps exceeding the limit, automatically adjust the distance between the cover plate and the cylinder, and automatically grind the cover plate to stabilize product quality.
( 6) After long-term practice and testing, the general nep control standards are as follows:
Raw cotton 200 grains/g
Open cleaning cotton 400 grains/g
Carded 80 grains/g
Combed 20 grains/g
Based on the initial processing of raw cotton and the quality of raw cotton itself, the general neps ration is 200 grains/g, with a low of 100 grains/g and a high of 400 grains/g.
The neps in the blowroom process increase to 400 neps/g, with a low of 200 neps/g and a high of 700 neps/g.
The carding machine card sliver contains 80 neps/g, the highest is 200 neps/g, the lowest is 50 neps/g.
After combing and combing, the neps in the combed sliver are generally controlled below 20 grains/g.
The nep basis weight of other processes such as drawing and roving has not changed much, but has slightly increased. .
Immature fibers have a greater impact on increasing neps and short lint, and raw cotton should be controlled The distribution and content percentage of immature fibers when blending with cotton
The concept of foreign fibers refers to other fibers with different dyeing properties from cotton fibers, such as wool, linen, silk, and chemical fibers. In raw cotton Mixing these foreign fibers with different dyeing functions will cause dyeing defects in downstream processes such as knitted fabrics and woven fabrics, which will not only deteriorate the physical appearance quality, but also cause the spinning enterprises to be subject to claims and cause economic losses.
(1) At present, our country has entered the WTO. Domestic companies are using different processing methods to harvest and package raw cotton from all over the world. Domestic raw cotton is also mixed with foreign fibers, commonly known as “three silks”, which seriously threatens our country’s cotton textiles. Enterprise spinning Yarn quality and product quality in downstream processes. For this reason, many domestic companies have organized manpower to set up a workshop to pick “three yarns”. This requires a lot of labor and the effect is unstable and incomplete. It is a difficult problem to improve the appearance quality of spinning and fabrics.
(2) Currently, many blowroom cotton production lines have been equipped with technical equipment to remove foreign fibers. It uses the principle of photoelectricity combined with the meticulous opening technology of blowroom cotton to detect and remove foreign fibers, such as the SCFO foreign fiber detection and separation system of the German Truetzschler Company, which is installed in the feeding part of the carding machine.
can effectively exclude quite a few Fibers of the opposite sex, the basis for applying this technical systemConditions, the fibers must be separated and loosened in the blowroom process, and the fibers should be free and single-fiber as much as possible. In the blowroom-carding system, this device for removing foreign fibers should be installed in the feeding part of the carding machine. Will produce better results, reflected in the automatic winding machine The electronic yarn clearer can reduce the number of cuttings by 50% in removing foreign fibers, which improves the efficiency of the automatic winding machine. If the cotton cleaning system is not equipped with a device to remove foreign fibers, the efficiency of the electronic yarn clearer in the winding machine will be reduced. , it needs to be cut off about 40 times every 100,000 m.
( 3) The automatic winding machine only has an electronic yarn clearer that removes foreign fibers, but does not have a foreign fiber remover, so the electronic yarn clearer cuts off more times and the production efficiency of the automatic winding machine is low.
Only equipment for removing foreign fibers is installed in the opening and cleaning system, but there is no electronic yarn clearing function for foreign fibers in the automatic winding machine. The removal of foreign fibers is obviously incomplete.
Only if a foreign fiber yarn clearing system is installed in the blowroom cotton production, and a foreign fiber electronic yarn clearer is installed on the automatic winding machine, foreign fiber The cleaning can be more thorough and achieve better results
(4) There are many domestic foreign fiber removal devices and winding machine electronic yarn clearers, which can be selected according to specific circumstances.
ImmatureFiber: refers to the fiber cell wall is very thin, the middle cavity is large, and there is noThe cotton fibers are twisted and the fibers are in a band-like shape.
(1) Since the dyeing properties of immature fibers and mature fibers are different, the uneven distribution of immature fibers during the spinning process will cause crossbar defects in the defective cloth. The lower the immature fiber content, the more consistent the dyeing properties of cotton fiber and the less dyeing defects. few.
(2) Immature fibers have poor rigidity and low strength. Therefore, it will affect the production and quality of spinning production. Under the same conditions, Neps and short lint will increase, yarn breaks will increase, and production will be unstable.
(3) Foreign countries have already used the percentage of immature fiber content in cotton blends as an important indicator to control.
(4) Application of cotton fiber property detector Ruwu STER AFIS is an instrument that can accurately and quickly detect the distribution of immature fibers in raw cotton.
(5) It is recommended to pack a batch of raw cotton bags in the mixed cotton The percentage of immature fiber content between packages is within 2%, and the percentage of immature fiber content between batches does not exceed 0.5% ripe
Yarn hairiness is harmful in quite a few textiles, especially the warp and weft yarns used in air-jet looms, which require the warp and weft yarns to reduce hairiness as much as possible, especially harmful hairiness above 3 mm. However, some fabrics, especially yarns, contain Certain hairiness to give the fabric a certain style
(1) The main process that produces hairiness is spinning. There are two places on the spinning machine that have an impact on the generation of hairiness. One is the spinning triangle area, that is, the spinning area between the sliver drawn out from the nip of the front roller of spinning and the twisting point. triangle area, according to According to foreign data, the hairiness of spinning yarn produced in the triangle area accounts for 80% to 85% of the hairiness of the entire yarn, and more than 80% of the flying particles in the spinning workshop are generated in the spinning triangle area; the second is the winding part.
(2) The emergence of compact spinning technology basically eliminates the spinning triangle Therefore, the spun yarn has very little hairiness and the yarn body is as smooth as silk, which basically solves the problem of yarn hairiness in spinning production.
(3) The ring and traveler in the twisting part of the spinning machine are also the parts that produce spun yarn hairiness. The service life of most domestically produced rings and travelers is extremely low. The life of the ring is only 9 months and the life of the wire coil is only one week. Since the ring and traveler are not Matching, the stable period is too short, making the warp tension very unstable, especially In spinning production, the spinning tension of large yarns and small yarns is greater, non-denier will cause breakage, and hairiness will occur. In recent years, the service life of steel rings in my country has been increased to 3 years through the revolution of materials and processing technology. ~5 years, the life of the wire ring has also been improved, such as fluorine-plated steel wire ring.
Overseas, steel rings are generally produced, and the wire rings are in one company. The matching shapes of the steel rings and travelers are well designed, which prolongs the service life and improves the quality of matching. For example, the Swiss Bruker wire rings and steel rings The matching condition is very good, and the contact surface between the two is enlarged, which improves the heat dissipation effect and extends the service life. According to the factory’s experience, the matching condition of the ring traveler will significantly reduce hairiness.
(4) The rollers, rubber rollers, aprons, yarn guide hooks, upper and lower pins, collectors, etc. in the spinning components all play a certain role in reducing hairiness. How to reduce hairiness without compact spinning technology? It is also a positive measure to reduce the spinning triangle as much as possible
(5) The motor of the new spinning machine is frequency controlled and can be divided into 10 levels according to the spinning process from small yarn to large spindle speed to control the spinning process. The yarn tension is consistent and stable spinning tension can reduce the hairiness of large and small yarns.
(6) Effects of yarn hairiness on air-jet looms Efficiency improvement is very relevant. According to surveys, when air-jet looms use ordinary ring-spun yarn, the warp and weft stops caused by hairiness account for about 2/3, so the hairiness issue deserves special attention.
(7) Due to the uneven distribution of hairiness and large spindle differences, the fabric will have horizontal rail dyeing defects caused by hairiness.
(8) The automatic winding machine has achieved consistent automatic control of the unwinding tension from large yarns to small yarns and the winding tension of the winding machine, which also has a positive effect on reducing the amount of hairiness produced during unwinding of the bobbin.
(9) The effect of the winding machine on the increase of hairiness is aimed at the situation where the hairiness of ordinary ring yarns continues to deteriorate and the hairiness increases significantly, but it does not Including yarns with little hairiness in compact spinning, the winding machine will not affect the significant increase in hairiness of fine yarns.
(10) In the new spinning system, since there are basically no spinning triangles and ring and traveler twisting systems, the hairiness on air-jet spinning, vortex spinning and rotor spinning yarns is less than that on ordinary ring-spinning yarns.
(1) The strength characteristics of the original yarn include average strength, strength unevenness, average elongation and elongation unevenness . Generally, the average strength of warp yarns is 15 cN/tex, and the strength unevenness is about 9% to 10%. The average strength of weft yarns is 12 cN/tex, and the strength unevenness is about 9% to 10%. The average elongation at break is generally controlled within 2%.
(2) The important strength indicator for the stop of the air-jet loom is the strong weak link, that is, low strength. It is generally believed that when the yarn fineness is only 40% of the normal yarn, this detailed weak link will inevitably cause end breakage and cause the machine to stop. If the strong weak link is at 4 cN/tex, elongation less than 2% will inevitably cause breakage.
(3) In addition to detail defects accounting for 61% of other strong and weak links, other weak twists, poor joints, and mixed thick joints can also cause warp and weft gaps. Stop, about 39%
(4) In addition to average strength and uneven strength, the strong factors that cause warp and weft yarns to stop are strong and weak loops. Japanese businessmen go to China to buy yarn, especially the number of strong weak loops of 100,000 wefts based on high-speed and large-capacity strong. Machine tensogiet detects 100,000 latitudes The possibility of yarn purchase is judged by the broken ends. Therefore, in the strength requirements of yarns in knitting and weaving factories of considerable scale, special emphasis should be placed on the level of strength and weak links. Some relevant enterprises in my country should be equipped with tensogiet strength meters as much as possible to check the original yarn. Quality matters.
(5) There are three main types of details on the original yarn: one Short velvet details, one is at the knot of thick details, and the other is long yarn knots or multiple short details connected together will cause breakage.
(6) In order to reduce strong and weak loops and provide good conditions for downstream processes For the original yarn, corresponding measures must be taken, such as using a four-unit drive four-roller drafting shape.The new type of roving frame, on the one hand, eliminates the details caused by the switch car, on the other hand, it improves the drafting sliver and reduces coarse and detailed defects, etc. It also strengthens the transmission tooth key coordination of the drafting part to prevent it from loosening gaps. Ensuring synchronization of the drafting process is also one of the important ways to reduce details.
Also Reasonable configuration of technology and selection of good drafting components, such as rubber rollers, rubber rings, upper and lower jaws, and pressure mechanisms, are also factors that reduce details.
Irregularity indicators include weight unevenness and evenness unevenness. Generally, spinning mills pay more attention to unevenness and have a high level of monitoring. There are not many here Discussion.
(1) The new blowing and carding double cotton box cotton feeder uses a pressure sensor and a variable frequency speed motor to control the density of cotton batts in the cotton box, so that the cotton layer fed to the carding machine is consistent vertically and horizontally, and the cotton layer is uniform in length and width. Uneven weight can be controlled at 2%~2.5%
(2) In the carding machine The open-loop, closed-loop and mixing loop auto-leveling mechanisms of each process of pre-spinning equipment such as draw frame and combing machine all play a positive role in improving the unevenness and weight of the finished yarn.
(3) The drafting components of the draw frame such as the cradle, rollers, bushings, etc. have been greatly improved, which has greatly improved the unevenness of the medium and short segments.
(4) The final drawing is equipped with a slub monitoring device and the roving is equipped with a tension monitoring system, which has a positive effect on improving the yarn evenness.
(5) Most spinning mills are equipped with offline monitoring evenness meters, with a high frequency of monitoring, so that evenness, thick details, and nep defects can be discovered in a timely manner and resolved in a timely manner.
(6) The advanced final draw frame is equipped with The online USTER autolevelling and monitoring system can monitor the evenness level of the draw frame online, and offline monitoring can generally be canceled.
(7) The implementation of a series of online and offline monitoring technologies enables The spinning quality is well guaranteed, generally reaching the level of 25% of the bulletin, and some can reach within 5%.
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