In the spinning process, when the spinning tension is greater than the strength of the cotton yarn, it will break, which is the essence of the spun yarn break. The average value of the two must be that the strength of the cotton yarn is greater than the spinning tension, otherwise the spinning cannot be performed normally. Spinning tension and cotton yarn strength are fluctuation variables. When the maximum value of the spinning tension is greater than the minimum value of the cotton yarn strength, the end will be broken. Therefore, one of the basic ways to reduce the yarn breakage is to reduce the maximum value of the spinning tension to reduce the tension and fluctuation as much as possible.
Factors affecting fluctuations in spinning tension
1) Instability of high speed running of ingot belt. When the spindle diameter is 22 mm and the spindle speed is 20 000 r / min, the linear speed of the spindle belt running is as high as 1382.3 m / min. Because the spindle belt drives the spindle through friction, it will directly affect the stability of the spindle speed. Therefore, the quality of the spindle belt and the running state have a greater impact on the fluctuation of the spinning tension.
2) Instability of high-speed spindle rotation. Spindle high-speed rotation is the power source of spinning tension and balloon. Defects such as uneven rotation speed, vibration, and up and down of the spindle will affect the stability of spinning tension.
3) The bobbin is of poor quality. Spinning is achieved by the bobbin. If the bobbin is of poor quality, the bobbin is shaking, the bouncing up and down, and the bobbin and the spindle are not well meshed, the synchronous rotation of the two will make the bobbin speed uneven, which will affect the stability of the spinning tension. .
4) Influence of ring and traveller. Rings and travellers are at high speed, high pressure and high temperature during spinning. When the spinning frame uses a 42 mm diameter steel ring and the spindle speed is 16 000 r / min ～ 20 000 r / min, the traveler wire speed can reach 35.2 m / s ～ 44 m / s, and generate a high temperature above 300 ℃ . According to testing calculations, the contact pressure of 18.2 tex cotton yarn when the tube bottom is formed into a large diameter is 243 cN. It is assumed that the instantaneous traveler's contact area to the ring is 0.1 mm and the contact pressure is 24.3 MPa during the traveler's ripening period. It is 1.34 times the highest limit value of 18.1 MPa specified for the surface pressure of the crankshaft bearings of aircraft engines. The traveler rotates on the ring at high speed, high temperature and high pressure under special conditions, which has a greater negative effect on the stability of the spinning tension. The traveller on the ring rotates at the high speed and swings at the meridian plane, horizontal plane, and cross-section, respectively, and rotates at the same time. Vibration and frustration occur. Wedges occur when the tilt and swing are excessive, which causes the spinning tension to embarrass. Therefore, the reasonable selection of ring and traveller has a significant impact on the change in spinning tension.
5) The three-point concentricity of the spindle, ring and guide hook is poor, which increases the probability of swing, tilt and wedging of the traveler in the ring space, and generates tension fluctuations.
6) The spinning balloon makes the cotton yarn swing to a certain width around the back and inside of the inner ring of the yarn guide hook. If the swing section is not horizontal, the balloon will be unstable or form balloon, which will affect the spinning tension stability.
7) The yarn separation plate is skewed, which is easy to cause spinning balloon and hit the yarn separation plate, making the spinning tension unstable.
8) The traveler cleaner is frayed or the traveler-to-cleaner separation is too large, which cannot effectively remove the flying flowers entangled on the traveler, which makes the spinning tension unstable and tends to increase.
9) Vibration and throbbing during the lifting of the ring plate can also easily cause unstable spinning tension.
10) In the spinning environment, flying flowers are attached to the spinning balloon or the air-conditioning air outlets are not distributed reasonably, and the air flow will interfere with the spinning balloon to make the spinning tension fluctuate.
Technical measures to stabilize spinning tension
Ingot subsystem
1) The spindle tip and bottom bearing, spindle rod and upper bearing must not be worn;
2) Do not shake the spindle, and it is strictly prohibited to jump up and down;
3) Spindle feet should not be lukewarm and vibrate;
4) Regularly check the eccentric bending of the calibrated spindle and disc;
5) The length and tension of the ingot belt are normal. Do not rotten edges or twists. Do not stain with oil or accumulated fibers. Do not rub the edges of the ingot and roller. The joints must not be thick and hard.
6) The surface of the spindle reel and the bearing must not be worn, the bearing should be cleaned regularly, there should be no hardened greasy dirt, and it should not be beaten or shaken during rotation;
7) The head of the bobbin must not have burrs or damage. The upper eye of the bobbin and the taper of the upper part of the spindle are tightly meshed to ensure that the spindle and the bobbin rotate synchronously. There is a slight gap between the lower mouth of the bobbin and the lower clock post.
8) There should be no wire loop between the bobbin and the spindle;
9) Do not shake the bobbin, shake it up and down, or jump the pipe.
Steel ring traveller and balloon system
1) Rings must not have rust spots, and there must be no burrs on the upper mouth and traveller track.
2) As the ring wears, it is necessary to exchange the ring service cycle normally. For the normal regrind cycle of the traditional ring, use a planetary polisher to regrind the ring and use high-quality abrasives and abrasives. Pay attention to the regrind method to improve the regrind quality. .
3) The position of the ring plate should be kept in a straight line regardless of the position of the small yarn to the large yarn. The ring plate should be horizontal from left to right and front to back. The ring should be fastened to the ring plate and should not be loose or inclined. Do not vibrate or pause during lifting.
4) Select the optimal traveller type. The traveler weight is reasonably adjusted according to factors such as cotton yarn strength, ring condition, spindle speed and traveler wire speed, balloon shape, end break distribution, temperature and humidity fluctuations, and cotton hairiness.
5) The traveler replacement cycle is correctly formulated according to the number of broken ends and hairiness, and is carefully implemented to prevent individual travellers from missing.
6) The spindle level is carefully calibrated. The three centers of the spindle, ring, and guide hook are carefully aligned. This is only static, and dynamic verification must be done to lay the foundation. This position aligns the two centers of the spindle and the ring, and readjusts the hanging of the yarn guide hook for readjusting the position of the spindle.
7) The yarn guide hook must not be worn or loose, and the yarn guide plate must not be loosened. The yarn guide hook must be flush regardless of the position of the small yarn to the full yarn.
8) There must be no burrs on the gauze plate, and it must not be skewed or loose when installed between the two spindles.
9) The traveller cleaner distance tool is reasonable in design and accurate in manufacturing. The cleaner must not be loose, rusty, and the distance is too small.
10) The spinning balloon should not be skewed. If the twisted balloon is caused by the inner side of the inner hole of the yarn guide hook being not level, the yarn guide hook should be replaced and disabled; the spinning balloon should be stable and not vibrate. It has a small arc shape; the balloon cannot rub the bobbin head and touch the screen.
11) Regularly check that the deviation of the flatness of the ring on the ring and the roundness of the inner hole is not greater than 0.05 mm. The actual depth on the inside of the traveller track of the ring cannot be less than the design depth.
Stabilizing spinning tension and reducing spun yarn breakage is a comprehensive, complex, meticulous and comprehensive system engineering, and basic management tasks such as equipment, technology, operation, raw materials, temperature and humidity of the enterprise, and various items to improve quality. Measures are closely related. To achieve good results, we need to take overall consideration and integration into consideration and adhere to the meticulous and continuous improvement of various technical and management tasks.
