Analysis of Small Cotton Bundle Yarn Defects in Roving
If the air suction of carding is not good, the air flow of carding is disordered, the internal chaotic fibers and short fibers in sliver are more, and the drawing distance is not appropriate, the fiber straightening parallelism is poor, the evenness of sliver is poor, and the roving can not be pulled will cause short slub.
Roving produces cotton bundle yarn defects in two cases:
1. Only rough, no details or details are not obvious. The reason for this is usually drawing. Sometimes the hanging flower of roving will form. But it is certain that this situation has nothing to do with the drafting area of roving.
2. Follow the details closely behind the rough sections. This situation can be sure: the problem must occur in the roving drafting area, generally caused by the poor rotation of the upper and lower coils.
Possible causes of yarn defects in roving bundles:
1. High content of short fibers and unsuitable moisture regain are found in the raw materials; there are super-long multiple fibers in the raw materials of chemical fibers;
2. Cleaning and combing cause more damage to fibers, resulting in a high growth rate of raw sliver short fibers, poor fiber separation and orientation, bundle fibers and random fibers in raw sliver;
3. Due to unreasonable drafting process design, such as drawing quantity, roller gauge, roller pressure, drafting distribution and merging number, as well as overlapping feeding of strips, improper use of pressure bar or poor condition, the fiber straightening parallelism and evenness in ripe strips are poor, resulting in the roving drafting can not be maintained.
4. Due to the unreasonable process design of roving roller gauge, nipper gauge, roller pressure and draft distribution, the roving draft is poor; the top pin is deformed and skewed; the leather ring is too hard, the inner diameter is inconsistent, the surface is greasy, seriously concave or deformed, the leather ring is not flexible to rotate, and the upper and lower leather rings run in different diameters; Too small, too high hardness, too smooth surface, serious concave, too thick or uneven layer; roller or iron roll rotation is not flexible, uneven speed, position is not correct or skewed; clamp spacer block is missing or misused;
5. Combing, refining, merging, rough sliver and yarn passage are not clean, resulting in sticking, hanging, winding, accumulation and banding;
6. The cleaning devices of fine, coalescent and coarse are not effective, resulting in the accumulation of short velvet on the velvet belt and the velvet board to be attached to the strip.
7. Moisture regain of ripened sliver and temperature and humidity of roving bladder are not suitable.
8. The bar joints of the block lathe are not qualified, such as hand rubbing head and lap head.
In order to solve this problem, because pure viscose requires high temperature and humidity, humidity is not enough, and rough section is very easy to produce velveteen, if the cleaning device is not effective, velveteen is brought into the sliver, forming cotton bundle yarn defects. The humidity of rough section should reach 75%. In addition, the use of nylon coating for roller is helpful to reduce flocking.
In addition, if the cotton bundle yarn defect is inherent, like normal sliver fibers, that is the roller gap is small, appropriate enlargement can be done.
Another is that if there is no problem with the back sliver, there is a problem with the roving process settings, and the draft force is greater than the grip force, which leads to the phenomenon that the draft cannot be opened.
Other influencing factors: hanging flowers and collecting flowers in the Sirindoff triangle area; large distance between the front and bottom cover plate outlet of the Sirin, poor damage and transfer of the Dough card clothing; small draw suction, short velvet of the suede is not sucked away by the suede and is brought back into the sliver by the suede; coil inclined pipe, chassis hanging flowers; bad pressure of the rocker; small separation of roving, draft points Improper matching, spindle wing hanging flower, velvet flower brought in; temperature and humidity changes greatly, etc.
There are many causes of yarn defects in small cotton bundles produced by roving. While strengthening equipment maintenance and strict operation management, the selection of process should not be neglected. Reasonable optimization of process parameters is the guarantee of stable product quality, in order to produce good cotton yarns satisfying customers.
