Closed suspension spindle wings have many advantages in use, but some spinning mills have discovered during use that there are yarn defects caused by hanging and accumulation of flowers. Some people even think that this is something that closed suspension spindles cannot overcome. disadvantages. This article focuses on analyzing the shape, causes and prevention methods of yarn defects in closed suspension spindles.
1. Hanging flowers
In the normal spinning process, when it is found that a certain roving gradually Sagging, the spinning tension is obviously smaller than other rovings. If the car is stopped, unwind the lower part of the bobbin for a few turns and then pull the roving upwards from the spinning part. At this time, you will find a cluster of cotton fibers on the pulled out roving, like Such as squirrel tail, commonly known as “cotton rat”, this form of yarn defects we call “hanging flowers”. Hanging flowers will cause the roving to sag or break, but it is easier to find if it enters the roving. The cause is often caused by defects in the false twister or the inner wall of the stainless steel tube. When the roving is pulled out, “cotton rats” are brought out, which is often false. The twister defect can be eradicated by replacing the false twister; if the “cotton rat” is a certain length below the lead-out end, the inner wall defect of the channel is a certain length below the pipe mouth. At this time, the spindle wing needs to be repaired. The channel should be cleaned or polished to remove dirt or defects on the tube wall. If scratches still occur after treatment, the spindle flyer can be replaced by the spindle flyer manufacturer.
2. Jihua
If the machine stops during the spinning process, it will It was found that many spindles or even all the rovings had yarn defects. Some of the yarn defects were as small as mung beans, and some were as large as caterpillars, several centimeters long. The yarn defects were composed of yellow lint and dust. This kind of yarn defects composed of short velvet dust accumulated at the lower nozzle of the roving channel is called “accumulation flowers”. The causes of accumulated flowers are complex: they are related to factors such as the type of roving being spun, the concentration of dust in the air, the roughness of the inner wall of the stainless steel tube, etc., but the most fundamental reason is determined by the structural characteristics of the closed suspension spindle flyer. From the Bernoulli equation, we know that when an ideal gas flows continuously in a gravity field, the potential energy, pressure energy and kinetic energy of unit mass of gas along the streamline can be converted into each other, but the sum remains unchanged. The Bernoli equation of unit mass fluid is: P/ρg+Z+V2/2g=constant. When the height difference between the two sections in the flow field is not large, the above equation can be simplified as: P/ρ+V2/2= constant.
The high-speed rotating suspended spindle flyer has a very high relative speed with the air at the exit of the roving channel. Taking a flyer with a roving package diameter of 150mm as an example, the spindle speed is 1000r/ min ~ 1600r/min, the relative speed between the lower nozzle and the air reaches 9.2 m/s ~ 14.8m/s. Such high kinetic energy will be converted into pressure energy at the nozzle on the roving channel, so the closed suspension spindle When the wing is working, a negative pressure is formed at the nozzle of the roving channel, that is, the false twister. Even if no roving enters, the high-speed rotating suspended spindle wing will always suck air containing dust into the roving channel. Short lint, dust in the air will The impurities at the lower nozzle accumulate on the outside of the tube wall due to the influence of centrifugal force and hydraulically roughened tubes. When the running roving frame is stopped for some reason and then restarted, this accumulation will fall down under the action of gravity and the vibration force generated by the sudden start. As the roving enters the package, accumulated yarn defects are formed.
The accumulated yarn defects are more serious in carded yarns with high dust concentration and high short lint content in the workshop, while in combed and cotton and chemical fiber blended yarns Barely present during the process. The closed suspended spindle wing structure commonly used in foreign countries is the same as that in my country, but the phenomenon of accumulated yarn defects is rarely reported. The main reason is that the cotton dust concentration (mg/m2) in workshops stipulated in developed countries is far lower than that in my country, such as: The United States is 0.2, the United Kingdom is 0.5, Germany is 1.5, and Italy is 1.0. According to relevant information, the actual dust concentration in the air in the rough processing section of cotton textile factories in different regions of my country is generally about 5 mg/m2. In order to reduce power consumption, some factories reduce the number of air changes in the workshop, which greatly increases the dust concentration. Some private enterprises have launched in a hurry and do not even have an air conditioning system. Half an hour after entering the workshop, there is a layer of “cotton net” on the head. In such a situation Under such conditions, the accumulation of yarn defects in roving frames with closed suspended spindle flyers is more serious.
Prevention and control of accumulated yarn defects: First, the flyer manufacturer is required to further improve the smoothness of the inner wall of the stainless steel pipe, changing it from a hydraulically rough pipe to a hydraulically smooth pipe. The fluid does not produce vortex, preventing lint and dust from accumulating at the outlet. The second is to adopt an anti-yarn defect pressing palm that applies the principle of “continuous suction and continuous discharge”, so that the cotton dust accumulated at the nozzle can be continuously discharged with the roving, and yarn defects will not be formed if it is not concentrated. The third is to clean the roving channel regularly to keep the channel smooth and pollution-free, so yarn defects can generally be avoided.
3. Strip yarn defects
When the raw cotton used in the spun roving is machine-picked cotton, which contains a lot of impurities such as leaf scraps and seed scraps, after the roving slivers enter the spindle airfoil, the heavier leaf scraps, seed scraps, etc. will be removed from the yarn slivers under the action of centrifugal inertia force. The lint is separated and thrown to the outside of the spindle wing and mixed with the inhaled lint, and accumulates on the outside of the steel pipe on the shoulder of the spindle wing. When the roving machine stops and starts again, the strips mixed with leaf chips and seed chips will enter The roving forms strip-shaped yarn defects.
Prevention and treatment of strip yarn defects: First of all, the roughness of the inner wall of the stainless steel pipe should be increased to Ra≤0.2μm, and measures should be taken to prevent the oxidation of the pipe wall when casting the spindle flyer. Reduce the friction coefficient between the pipe wall and the cotton. Secondly, the steel pipe should be able to expand and contract freely in the mold. When the high-temperature aluminum liquid contacts the steel pipe and thermal elongation occurs, it should be able to move freely.Move without creating a blind spot on the shoulder that exceeds the straight line of the steel pipe. The above two points are what the spindle wing manufacturer should pay attention to. However, when a strip yarn defect is discovered in a cotton spinning mill, the spindle wing has already been formed, and the following methods can only be used to remedy it: ① If the roving frame has a traveling air blowing and suction device, two lines of aligned front air blowing pipes can be drawn downwards from the front blowing pipe of the machine. , the air nozzle of the rear row of spindle wings uses the intermittent wind blowing to the false twister hole of the spindle wing to discharge the dust on the shoulder of the spindle wing. ② If the roving air blowing and suction device is not used, the air flow drawn out by the dry flyer cleaning machine created by Wuxi Chengben Textile Machinery Co., Ltd. can be used to move longitudinally along the machine several times during the doffing process. The air flow blown out by the rear air nozzle can discharge strip yarn defects.
4. Roving channel cleaning
Although the closed suspended spindle flyer has many advantages, “Difficulty in cleaning” has become a worry for many users. Tens of thousands of meters of rovings pass through the spindle wing channel every day. Cotton wax, insect feces on the roving fibers, oils on the chemical fibers, etc. will gradually accumulate on the channel wall, greatly increasing the resistance of the rovings and reducing the spinning tension. , causing yarn defects such as hanging flowers and accumulated flowers. Therefore, when it is found that the spinning tension of each spindle position on a car is uneven and the end-breakage rate tends to increase, the roving channel must be cleaned and maintained, otherwise the spinning quality and the production efficiency of the roving machine will be affected.
Open suspension spindles generally use a soft cloth dipped in cleaning solvent and pulled back and forth in the channel to remove dirt. Cleaning is laborious and may cause the paint on the roving channel to fall off, exposing the The aluminum body causes damage. The following methods are currently available for cleaning the closed suspended spindle channel:
4.1 Wet spindle wing cleaning machine
The principle It uses an aqueous solution heated to 80°C to 85°C and added with cleaning agent, and sprays it onto the wall of the roving channel through the pipeline at a certain pressure to remove dirt on the wall. The ejected liquid can be recovered and passed through the filtration system for recycling.
However, the trial effect is not ideal. The reason is that the dirt on the wall of the spindle roving channel is the result of accumulation over time. The dirt has a strong binding force with the pipe wall. Difficult to remove dirt. Another disadvantage of this cleaning machine is that the spindle flyer must be dried after being sprayed with liquid, otherwise it cannot spin.
4.2 Semi-mechanized cleaning method
Introduced in the “Zhongshi Spindle Flyer User Manual”: For The cleaning of the closed suspended roving channel is carried out in three steps: dissolving, cleaning and wiping. The first is to dissolve pollutants: use a high-speed power station (3000r/min) to clamp a flexible shaft dipped in solvent (the core is a flexible shaft, the outer layer is wrapped with cotton yarn) and rotate it in the channel for 2-3 minutes (depending on the degree of pollution). When rotating, the hand-held electric drill moves up and down (the stroke is no more than two centimeters), and the pollutants on the channel wall are dissolved through the grinding of the solvent and the flexible shaft. Generally, the flexible shaft can only be cleaned for 2 to 3 tablets after being dipped in solvent. Then it needs to be dipped in solvent again to remove some of the contaminants transferred to the flexible shaft. The second step is to remove pollutants: pass the iron wire with a soft cotton strip dipped in solvent at the end through the channel, pull the iron wire by hand to make the cloth strip pass through the channel, and take away the dissolved pollutants. Finally, clean the channel: pass the iron wire with a clean soft cotton strip hanging at the end through the channel, pull the iron wire by hand to make the cloth strip pass through the channel, and the cleaning work of the spindle is completed.
Although the above method is simple and easy to implement in practice, the effect of implementation in cotton spinning mills is often not ideal. The main reason is that the following situations are prone to occur during the implementation process:
a. The flexible shaft and cloth strips dipped in solvent are cleaned too many spindles at one time, resulting in some contaminants on the spindle wings not being effectively dissolved or removed.
b. If the soft cloth strip does not fill the lumen of the tube during operation, and it is easy to pull it, it will not be able to truly clean the tube wall.
The above manual operation methods often vary from person to person and from time to time. The operation is laborious and inefficient, and the cleaning effect of different operators varies greatly. It is difficult to truly solve the problem of cleaning the closed suspended roving channel in cotton spinning mills.
4.3 Dry spindle wing cleaning machine
This device is powered by compressed air and uses pneumatic The grinding head holds a cloth soft shaft dipped in solvent to dissolve the contaminants in the channel, and then uses a special air gun to drive several special “warheads” into and through the channel to achieve the purpose of removing contaminants and wiping the channel. Compared with the above two cleaning methods, this dry spindle wing cleaning machine is more suitable for use in cotton spinning mills: First, the special “warhead” is configured according to the inner diameter of the channel, which can pass through the channel close to the pipe wall, and the cleaning effect is not affected by humans. Secondly, under the action of the special air gun, the “warhead” can be operated through the channel conveniently and labor-savingly. Some warheads can be cleaned and reused, resulting in low operating costs. Since it is dry cleaning, the channel does not need to be dried, which can greatly shorten the time of cleaning the channel.
The multifunctional dry flyer cleaning machine is equipped with a special quick interface controlled by flow adjustment and control. Combined with a special spray gun, it can be used on roving frames without circulating blowing and suction devices. Itinerant removal of strip sediment accumulated in the spindle shoulder channel can effectively prevent and control the occurrence of strip yarn defects. </p
