Fabric Products,Fabric Information,Fabric Factories,Fabric Suppliers Fabric News To control neps and linters in the drawing process, how to set up the drafting process?

To control neps and linters in the drawing process, how to set up the drafting process?



The drafting process of drawing can be divided into two types: “reverse drafting” and “forward drafting”. What they have in common is that they can both improve the evenness of the evenn…

The drafting process of drawing can be divided into two types: “reverse drafting” and “forward drafting”. What they have in common is that they can both improve the evenness of the evenness and improve the straightness of the fibers. However, the emphasis between the two is different in terms of separation, and their shortcomings are also obvious. It is best to realize the advantages of both and overcome their shortcomings, so that the drawn fibers can be well controlled and the uniformity and fiber straightness can be improved.

Draft distribution adopts “reverse draft” Stretching, large back area”

First, the total drafting process adopts “reverse drafting”, and 8 slivers are fed in together. Increase the total draft ratio of the first pass, as long as it is slightly higher than the combined number, and the final draft requires a slightly lower draft ratio than the combined number. Secondly, the first pass and the last draw use increasing multiples in the back zone, that is, the first draw is expanded to between 1.75 and 2.10, and the last draw is expanded to between 1.30 and 1.35. Assume that the third pass and the second pass are The parameter is between the first channel and the last channel, and it is easy to be too large at this time. If you use the spacing of the large back area of ​​the drawing to cooperate, the effect will be better.

The new process mainly uses “reverse drafting”, which ensures the uniformity of the evenness, and then increases the drafting multiple in the rear area to improve the straightness of the fiber. , separation and parallelism, giving full play to the advantages of “smooth drafting”, reducing the level of neps and short lint as much as possible, and at the same time increasing the production speed of the draw frame.

In practice, this method is completely suitable for the production of pure cotton varieties, and can also achieve good results on chemical fibers, wool, linen, etc.

When the total draft ratio of the first pass is higher than the combined number. When the first pass multiple of “back drafting” is higher than the combined number, it will cause the entire sliver to deteriorate, and as the multiple continues to increase, the degree of deterioration will continue to increase. This is also the main feature of this method. . The first draw processing mainly focuses on fiber straightness, separation and mixing, rather than solving the problem of evenness. Through production practice, it has not been found that the overall evenness is affected by the use of “reverse drafting”.

The main purpose of increasing the first pass drafting ratio of “reverse drafting” is to arrange all drafting tasks in the first pass, thereby avoiding excessive pressure on the last pass , and increases the adjustment space for the entire final draw to ensure the completion of various indicators.

Reducing neps

The total draft distribution uses “reverse draft”, and each lane is parallel The strip is mainly higher than the draft ratio of the rear area. The draw ratio of the first pass is basically maintained at 1.8 to 2.1. Generally, the feeding amount is less than 22 g/(5 m) (10 pieces are fed). When the feeding amount is above 22 g/(5 m), the first pass The drafting ratio in the back zone of drawing must be continuously increased, and once the sliver quantity is relatively large in the production process, the draft in the back zone must be enlarged, so as to maintain better results.

The purpose of increasing the drafting area after drawing is to take advantage of “smooth drafting”, increase fiber straightness and separation, and avoid the generation of neps.

Open the “live nep”

The draw frame is in the process of merging and drafting It not only straightens the fiber hooks and undertakes the main task of blending cotton, but after practical research, it is found that it can also open “live neps”, which also makes the drawing process one of the processes that can reduce neps in the yarn. Great space to explore.

The “live neps” mentioned here are not true neps. They are hooked fiber clusters in the fed slivers that are messy in direction due to various reasons. , if it is not straightened during the drafting process, the fiber clusters may become tangled into true neps under the action of friction. Therefore, they must be adjusted during merging and drafting to open them into normal drafting. Stretched fiber strands, and live neps that failed to open will evolve into real neps.

This method is difficult to understand thoroughly through theory, but it has good results in production practice. Therefore, in order to reduce the formation of neps in the drawing process, increasing the post-drafting method can achieve better results.

With the increase of the drafting ratio in the rear area, the drafting in the main area will be further reduced, so the middle drawing among the three drawings takes the lead and the last drawing. Good results can also be achieved by adjusting the middle value of the path and using a larger control.

Normally, neps account for about 20% of all yarn defects.

It is worth noting that to achieve the above drafting purpose, major obstacles must be overcome, mainly due to: ① At high speed, the sliver passes through the space between the two rollers. The time is very short, so a relatively large gauge is required to complete its function; ② Because there is a certain angle between the surface roller grain and the roller busbar, the fiber will tilt in the direction of the roller grain during the drafting process. If the gap is The distance is not large, and neps are easily formed; ③ Larger drafting in the back area must have a larger gap space, otherwise the drafting will not be able to open, and it is easy to form long, thick and thin.

Reduce cotton linters

The increase in the draft ratio of the rear area must be accompanied by the draft of the main area. Extended lowering. Moreover, it has been found in practice that it is not the gauge but the draft multiple that breaks the fibers. The broken long fibers form new short fibers and become spun yarn hairiness in the subsequent process. This is also the main reason why some manufacturers’ spun yarns have high hairiness and cannot increase their strength. On the basis of the previous one, once the back area increases by 0.1 to 0.2 times,��, hairiness usually decreases by approximately 20%.

Stabilize and improve evenness

Practice shows that: The increase will inevitably be accompanied by a decrease in the main zone drafting multiple, which can optimize the entire link, make the entire evenness index more stable, the entire curve smoother, and the fluctuation range of the index significantly narrowed. Usually on the basis of the previous one, once the back area increases by 0.1 to 0.2 times, the evenness will increase by 2% to 3%. </p

This article is from the Internet, does not represent Composite Fabric,bonded Fabric,Lamination Fabric position, reproduced please specify the source.https://www.tradetextile.com/archives/35810

Author: clsrich

 
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