The relationship between new spinning drafting elements and yarn quality
The principle of V-type draft spinning is that the V-type draft raises the center of the back roller by 12.5 mm, and the rear rubber roller is offset backward along the surface of the rear bottom roller, so that the center line between the rear rubber roller and the rear bottom roller is connected with the front middle bottom roller. The lines are connected at an angle of 25°~28°, thus forming a curved drafting area in the rear area, which enhances and expands the friction boundary at the rear jaw, greatly enhancing the effectiveness of holding the whiskers and moving floating fibers. control. At the same time, it is conducive to improving fiber straightness, which is about 3.55 percentage points higher than ordinary drafting, improving the yarn structure and improving the yarn quality. Here, the author combines a series of production tests to analyze the impact of the new V-shaped drafting element configuration on yarn quality, and explore effective ways to improve yarn quality.
Reasonable selection of high-quality rubber rollers and aprons
The use of domestically produced low-hardness, high-elasticity, non-treated rubber rollers has the effect of improving the evenness level of the yarn. It has been recognized by people that the characteristics and quality of rubber rollers and aprons themselves, the quality of production and maintenance by the factory, the diameter size, and the hardness combination have a significant impact on the good use of rubber rollers and aprons. To this end, we have conducted experiments and comparisons in the following aspects to improve the evenness of the yarn.
First of all, we chose low-hardness, high-elasticity, and micro-processed rubber rollers. The core of the technical performance of the micro-processed, low-hard, high-elastic rubber roller is its excellent resilience and uniformity of circumferential hardness, ensuring uniform holding force. At the same time, its surface has a certain astringency, which enhances holding power. For this purpose, we selected Anhui Qianshan BYC-2170 micro-processed, low-hardness, high-elasticity rubber roller and Wuxi No. 2 Rubber WRC-965 untreated, low-hardness, high-elasticity rubber roller for experimental comparison.
It can be seen from the test data that under the same process conditions, the BYC-2170 rubber roller has better yarn dryness than the WRC-965 rubber roller. The variation coefficient between tubes is small, the yarn is thick and detailed, and the neps are relatively reduce. Because the actual pressure of V-type drafting pneumatic pressurization is greater than the pressure of the spring cradle (20N~30N), and the selection of rubber roller hardness and elasticity must consider the pressurization state and the nature of continuous operation. Under the conditions of low hardness and high elasticity, the hardness of BYC-2170 rubber roller is 3 degrees higher than that of WRC-965 rubber roller. Its instantaneous elastic recovery ability is enhanced during rotation, ensuring the uniformity of the distribution of friction force and the gripping surface. force stability. Therefore, the yarn formation level of BYC-2170 rubber roller is better than that of WRC-965 rubber roller. However, when using BYC-2170 rubber rollers, you must pay attention to the quality of fine grinding and surface treatment, otherwise its excellent yarn-forming performance cannot be fully exerted, and the loading cycle will not be long and it will be easy to twist.
The diameter difference between the front and rear rubber rollers should not be too large
The V-shaped draft pneumatic cradle’s rear rubber roller moves backward along the rear bottom roller, which changes the ordinary rocker. The principle and method of frame pressure distribution, in order to explore the impact of the diameter matching of the front and rear rubber rollers of the pneumatic rocking frame on the yarn quality, we tried several groups of rubber rollers with different diameters for comparison.
The test data shows that the diameters of the front and rear rubber rollers are equal or the rear rubber roller is slightly larger, preferably no more than 1.5 mm. According to the pressurization principle and characteristics of the V-type pneumatic cradle, if the diameter of the front rubber roller is large and the diameter of the rear rubber roller is small, the pressure of the rear rubber roller will be reduced under the same pressure condition, and the diameter of the rear rubber roller will be reduced. The jaw position of the rear roller also needs to be raised, which weakens the V-shaped friction boundary effect in the rear area and weakens the control force of the rear jaw of the rubber ring, affecting the reasonable distribution of the drafting force and the drafting effect, worsening the situation. The yarn is dried. Therefore, the diameter difference between the front and rear rubber rollers should not be too large when using V-shaped drafting.
The hardness of the back gear rubber roller should not be too low
The use of low hardness and high elasticity rubber rollers in the front gear can significantly improve and improve the quality of the yarn, which has become a trend in the spinning industry An indisputable fact. The low-hardness, high-elasticity rubber roller has strong ability to hold fibers and has a wide and uniform friction force. As for the relationship between the selection of the hardness of the back roller and the quality of the yarn, we conducted different experiments. The test results show that the hardness of the back rubber roller should not be too low. The reason is that after the hardness of the back rubber roller is reduced, under the same pressure conditions, the nip line becomes wider, the ability to control fibers increases, and the strength of the friction boundary in the rear area increases accordingly. . The V-shaped drafting itself has enhanced and expanded the additional friction zone at the rear of the drafting zone, greatly strengthening the holding of the yarn and the control of the floating fiber movement in the rear zone. Using both at the same time increases the drafting Difficulty, resulting in insufficient drafting and uneven drafting, which in turn affects the evenness of the yarn.
Choose different types and elasticity of aprons
We selected aprons of different hardnesses for comparative testing. It can be seen from the test data that MD60 for the upper ring and H068 for the lower ring have better neps in terms of evenness, thickness and details, which fully proves that the apron matching should in principle be soft at the top and hard at the bottom. The purpose of choosing two types of rubber rings of different types is to prevent the “mirror phenomenon” caused by the same type of rubber rings having the same friction coefficient when the new rings are used on the car at the same time, which will cause the upper and lower new rings to not stretch when they are mature. resulting shortcomings. Therefore, choosing apron of different types and elasticities and using them in reasonable combination is more conducive to improving product quality.
The medium iron roller is replaced by a medium rubber roller
The medium iron roller plays a transmission and control role in the operation of the apron. During long-term use, it is affected by temperature, humidity and rubber. Affected by the acidity of the ring, the surface is prone to rust and contamination.��The inner layer of the apron is corroded, changing the friction coefficient of the inner layer and becoming astringent, causing the apron to run unstable and the sailing control to be unstable, resulting in slub yarn, deterioration of evenness, and an increase in thickness and details. After switching to the medium rubber roller, it will not rust during use, and it will be more flexible. The contact surface will be enlarged, the friction will be enhanced, the holding effect will be strengthened, the slippage of the apron will be reduced, and the apron operation will be more stable, thus making the drafting easier. It is stable and reduces drafting unevenness, which is beneficial to reducing evenness CV value and coarse and fine detail ratio.
Using new patented upper and lower pins
The upper and lower pins are one of the drafting elements of the spinning frame. In order to continuously improve product quality and added value, our company Experiments and comparisons were conducted on the new carbon fiber upper pin and Zhaodong’s new lower pin.
The test results show that the carbon fiber upper pin strengthens the control force of the apron on the fiber, makes the friction boundary distribution in the drafting zone more reasonable, forward and stable, strengthens the effective control of the fiber, and can effectively improve the yarn production quality. However, due to its structural characteristics, this kind of top pin is easy to accumulate flying particles and cause yarn defects, so cleaning and maintenance must be strengthened. Due to its scientific and reasonable structure and excellent spinning mechanism, the new lower pin can significantly reduce evenness CV value, details, thick places and neps. However, during use, due to the increased height difference between the curve and the straight part of the new lower pin, the accumulated fly flakes are not easily taken away. Cleaning work needs to be strengthened, and the drafting machine AAJH must be reasonably configured. LK‘PO[IUYUKT
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