Rotor yarn defects and their characteristics
Yarn defects are yarn defects produced during the spinning process and are an important part of assessing cotton yarn quality. Common yarn defects in rotor spinning are shown in the table below.
In addition to raw materials, feed product quality, and process configuration, the causes of rotor yarn defects are mainly related to the operating status of the equipment; operation, maintenance, It is related to factors such as management and workshop temperature and humidity, which are described below.
Mechanical status of equipment and yarn defects
Poor mechanical status of equipment causes yarn defects and poor forming main reason.
(1) Thick and thin yarn defects in the finished yarn are mainly caused by the poor condition of the feeding part. The main mechanical reasons include damage to the feeding horn, accumulation on the feeding roller, and bearings. Damage, rolling, knocking, improper clutch spacing, gear wear, etc.
(2) Slub yarn defects in the yarn are related to the poor condition of the opening roller, such as saw teeth of the opening roller, inverted teeth, broken teeth, and excessive rotation speed. Slow operation, sluggish operation of the rollers, improper clearance between the rollers and the cover, etc. When the gap between the rotor and the sealing cover is too large and the burrs in the condensation groove of the rotor are hung, slub yarn will also be produced.
(3) The weak twist of the yarn is mainly related to twisting components such as the spinning rotor. If the spinning device is not locked and air leakage occurs or the sealing ring fails, the rotor pressure wheel If the pressing amount is too small or the rotation is inflexible, the rotor rotation will slip, the negative pressure of the rotor is low, the dragon belt is damaged, etc., etc., all will cause weak twisting of the yarn.
(4) When the twist-stop, yarn guide tube, yarn guide and other mechanical parts are damaged and fluffed, they will inevitably rub against the yarn sliver and pull the yarn to form hairy yarn.
(5) When the impurity removal part is in poor condition, sesame yarn with dense neps and impurities will be produced. For example, the saw teeth of the carding roller are worn and affect the removal of impurities; the impurity discharge holes are clogged and the impurity discharge cavity is accumulated; impurities cannot be discharged when the process exhaust is blocked, etc. Especially for self-ventilating rotor spinning machines, when the process ventilation is not smooth, several spindles in the front part of the machine will be severely broken, making it difficult to drive. When hard impurities are embedded in the rotor condensation groove, it will also cause uneven regularity and uneven strength of the yarn.
(6) Poor bobbin formation is mainly caused by poor condition of the yarn take-up winding part, such as grooves on the yarn take-up roller, improper pressure, and excessive or excessive tension drafting. Small, the yarn guide is damaged, etc.
Operation and yarn defects
Many yarn defects in rotor yarn are caused by improper operation of the turner.
(1) Flying flowers, yarn waste, and poor wrapping of cotton sliver joints during splicing will form slubs, details, or slub yarns in the yarn.
(2) The rotor is not thoroughly cleaned during splicing (self-ventilation type), and the yarn is not spliced for a long time after the end is broken; oil-hand splicing is used, and oil stains are brought in during splicing; If the bobbin falls to the ground or the container is not clean, the yarn will be contaminated, resulting in black, gray yarn and oily yarn.
(3) Mixing old and new cotton slivers or using the wrong cotton sliver during check-in, or feeding broken slivers, will cause color difference or the yarn characteristics of the package will not match the specifications.
Maintenance and yarn defects
The quality of maintenance work also directly affects the finished yarn. The number of yarn defects.
(1) If the feeding plate is pressurized too much or too lightly, the slivers will be delaminated and produce unexpected drafting, resulting in increased yarn weight unevenness.
(2) Improper installation of the feeding horn, and premature feeding of cotton to the feeding roller during collective head spinning will cause thick spots or details in the yarn.
(3) Improper installation of the isolation disk, improper rotor cleaning cycle or incomplete cleaning will cause uneven yarn dryness and the formation of black and gray yarn. When the twist resistor is used incorrectly, the finished yarn will have color difference or hairiness due to uneven twist.
Working environment and yarn defects
The working environment of the workshop includes two aspects, namely the air content in the workshop Dust volume and workshop temperature and humidity. Both have a certain relationship with yarn defects.
(1) The dust content in the workshop directly affects the yarn defects of the rotor yarn. If there is a lot of dust in the workshop, the dust (including short velvet below 5mm) will be inhaled with a large amount of air. Spinner. When accumulated to a certain extent on the yarn path, thick details will be produced, forming slub yarn defects and soot yarn. Therefore, reducing the dust content in the rotor spinning workshop is an important measure to improve yarn quality and reduce yarn defects. To reduce the dust concentration in the workshop air, we should start from two aspects. One is to place the rotor spinning machine in a separate workshop and separate it from the previous workshop where the dust is discharged larger. The other is to reduce the generation of its own dust source. That is, increase the dust suction air volume and process exhaust volume to prevent the exhaust duct from being blocked and dust from overflowing.
(2) The influence of workshop temperature and humidity on yarn defects. When the temperature is within a certain range, yarn defects are relatively stable, but when the temperature and humidity exceed a certain limit, yarn defects appear. upward trend, so the temperature in the rotor spinning room should be controlled at 28°C, and the relative humidity should be controlled at 60% to 70%. However, due to the different effects of winter and summer climates, the requirements for temperature and humidity control are also different. Winter temperature It should be greater than 20℃, and the relative humidity should be between 60% and 65%. In summer, the temperature should be less than 30℃, and the relative humidity should be between 65% and 70%. </p
