First, rubber roller
Roller is an important drawing part in spinning process. Its quality and application technology have a direct impact on its use effect, service life and yarn quality. With the continuous development of modern spinning technology, the adoption of high speed and heavy pressure process puts forward higher requirements for rubber rollers.
1.1 Requirements for rollers under high speed and heavy pressure conditions
(1) The hardness of the roller should be uniform, the surface is smooth and the color is consistent.
(2) The length of the roller, inner diameter, wall thickness, surface height difference, outside diameter difference should be within the tolerance range.
(3) The surface of the roller is not allowed to have bubbles, cracks, lack of glue, and no obvious powder points after grinding.
(4) The inner wall is rounded, has a certain tensile strength, small permanent deformation, wear resistance, aging resistance, and has a certain elongation and appropriate hardness.
(5) Oil resistance, temperature and humidity have a certain adaptability and antistatic performance.
(6) The outer eccentricity is small, the diameter difference between the two ends is small, and the rubber roll is not shaken.
1.2 Influence of rubber roller on dry uniformity of yarn
Influence of roller hardness: The roller hardness is low, and from the analysis of drafting theory and practice, compared with the middle and high hard night, the uneven ratio of holding force is significantly reduced, and the drafting is stable and reliable, which is beneficial to reduce the additional uneven ratio in the drafting process. Generally speaking, Shore A hardness 63-72 degrees for high elastic low hardness roller; 73-82 degrees for medium elasticity and hardness roller; 83 and above are rollers with low elasticity and high hardness.
Under the same pressure, the length of the clamping surface of the low and medium hardness roller is longer than that of the high hardness roller, which is conducive to holding the fiber; When using low hardness roller spinning, it should be properly pressurized (not too large), and adopt small spacing and tight clamping process, which has good spinning effect and is conducive to reducing mechanical wear and energy consumption. The hardness of the roller is low, under the action of pressure, the holding clamp line composed of the roller is widened correspondingly, and the coefficient of dynamic friction is large, which can significantly increase the holding performance of the front roller clamp on the bar. Under the action of pressure, the jaw line composed of the roller is relatively wide. The jaws of the pliers are wide, so that the jaws of the pliers extend to both ends, resulting in a forward and backward thrust. Clamping line forward, narrow the weak twist area, is conducive to reducing yarn breakage; The length of the floating zone is reduced by the back of the jaw line, which is conducive to controlling the movement of the floating fibers and improving the evenness of the strip. The low hardness of the rubber roll makes the rubber roll have the characteristics of good elasticity, large surface deformation and strong vibration absorption ability, so that the dynamic holding force of the jaws remains relatively stable. The horizontal holding is uniform, and the edge fiber control ability is strong, which is conducive to reducing the loss of fiber, reducing flying, and improving the evenness of the strip. See Table 1 for the comparison of the influence of different hardness rollers on yarn yarn drying when the same ingot and roving are used.
Table 1 Comparison of the influence of roller with the same hardness on yarn yarn drying
1.3 In order to extend the service life of the rubber roll and prevent winding and breaking, the following points should be done:
(1) Spinning pure cotton, the pressure of the spinning frame is controlled at about 140N/ double ingot, and the yarn guide stroke is controlled at 8-10mm.
(2) When the variety is changed, the various processes should be replaced in time with the rubber roller that matches the hardness of the spun variety, not only to ensure the spinning quality requirements, but also to ensure that the life of the car guard is good, and the rubber roller is not wrapped.
(3) Each time before the rubber roller on the car, it is necessary to clean the rubber roller and carry out temperature balance treatment, so that the temperature of the rubber roller is consistent with the temperature of the workshop.
Second, rubber ring
Rubber ring is also an important component of the spinning drafting mechanism, and its performance and quality are closely related to the spinning quality. It is very important to choose good spinning rubber ring for spinning production.
2.1 Elasticity and hardness of rubber ring
The spinning process requires the rubber ring to have good elasticity and proper hardness, otherwise it will cause the fluctuation of the mouth pressure to increase sharply, thus affecting the dry uniformity of the yarn strip. Elastic requirements: to achieve "upper circle high, outer layer high; Lower ring, lower inner layer; Hardness requirements: make the upper ring soft, the outer layer soft; The lower ring is hard, the inner layer is hard; Inner diameter: make the upper ring slightly loose, the lower ring tight; Thickness requirements: thin upper ring, thick lower ring. When the upper and lower rubber rings are replaced at the same time, it is easy to cause large-scale fluctuations in quality. Therefore, the new and old rubber rings are used according to the cycle, and the spinning quality is stable. At the same time, the total thickness of the upper and lower rubber rings is controlled within 2mm, and the upper ring is generally 0.9mm and the lower ring is 1.0mm. Because the outer layer of the rubber ring is directly in contact with the yarn during the drafting process, under the pressure condition, the outer layer has better elasticity and lower hardness, so that the rubber ring has a certain elastic deformation, the larger the area surrounded by the surface of the strip, the better the tightness at the mouth of the rubber ring, and the horizontal friction is uniform, which is conducive to the fiber holding. The inner layer is hard, so that the rubber ring will not produce peristaltic deformation or plastic deformation when under pressure, and weaken the elasticity and holding force of the rubber ring in the yarn guide motion.
2.2 Size of rubber ring
The size of the rubber ring has a great influence on the dry uniformity of the yarn strip, and the inner diameter of the rubber ring should be mastered according to the principle of "the upper ring is slightly loose, the lower ring is tight". The inner diameter of the rubber ring is too loose, resulting in the wavy advance of the strip in the drafting process, and the fluctuation is severe, resulting in the upper and lower rubber ring can not be tight or slip, weakening the grip control of the fiber, resulting in the deterioration of the evenness of the strip dry. If the inner warp of the rubber ring is too tight, the rubber ring runs in a tight state, resulting in large resistance, inflexible rotation, easy slip and cause shaking, pause, and distortion of the roller, resulting in bamboo joints or hard heads, thick yarn sections, thick and short, black board dry shadows and many other problems, seriously affecting the quality of yarn.
The circumference of the rubber ring is selected to ensure the flexible rotation of the rubber ring, and to reduce the concave phenomenon of the rubber ring as much as possible to facilitate the holding of the control fiber. Therefore, the spinning mill must strictly control the inner diameter of the rubber ring, strictly inspect the old rubber ring that has been used for a period of time, and remove the problem rubber ring to replace it.
2.3 Thickness of rubber ring
The thickness of the rubber ring should be used according to the "thin upper ring, thick lower ring". The thickness of the rubber ring is one of the parameters that determines the mouth separation of the rubber ring. The honed rubber ring can achieve uniform thickness. In the production, the thickness of the rubber ring and the thickness of the upper and lower rubber ring should be controlled to ensure the stability of product quality. The total thickness of the rubber ring on the spinning frame is generally grasped at 2 mm left, such as the thickness of the upper rubber ring is 0.8-0.9 mm, and the thickness of the lower rubber ring is matched with 1.1-1.2 mm. If the thickness of rubber ring is not properly matched, it will seriously affect the quality of yarn. For example: if the upper and lower rubber rings are thin, the rubber ring will appear wavy in the advance; If the control is too thick, the rubber ring will be slippery in operation, which is not conducive to the upper and lower rings, so that the elasticity of the rubber ring can not be fully played, affecting the uniform distribution of friction.
2.4 Rubber ring width
The width of the rubber ring is narrower than the rubber ring frame, generally 0.75mm to 1.00mm is better, if the width of the rubber ring frame is too narrow, the edges of the rubber ring frame are easy to be embedded flying, affecting the normal rotation of the rubber ring, if it is too wide, the rubber ring is easy to collide with the rubber ring frame during operation, resulting in the rubber ring rotation is not flexible, the rubber ring frame shaking and other problems, will cause the deterioration of yarn quality.
2.5 Surface friction coefficient of rubber ring
The surface friction coefficient of rubber ring is one of the main characteristics of rubber ring, which directly affects the normal operation of spinning process. If the friction coefficient of the outer surface is large, it will produce static electricity, so that the fiber on the surface of the yarn is scattered and woolly, and the number of flying flowers is increased. The phenomenon of entanglement often occurs due to electrostatic deposition, and the adhesive fibers are carried away by the whisk during drafting, forming thick joints. The friction coefficient control range, the friction coefficient of the outer surface should be as small as possible, and the general static and static control is between 0.3-0.7; The dynamic and static friction coefficient of the inner layer of the rubber ring should be controlled between 0.4-0.7.
2.6 Mechanical properties of rubber rings
The mechanical properties of rubber ring, including breaking strength, elongation, cord properties, etc. affect the spinning quality, especially when the cord is broken and the rubber ring is constant, it will seriously affect the evenness of the yarn.
2.7 Inner pattern rubber ring
At present, the inner pattern strand is generally favored. The inner surface of the rubber ring under the inner pattern is a neatly arranged mesh structure, the height of the convex pattern is dozens of microns, and the raised pattern is composed of hilly curves, like the "arc island" and "peninsula" shape. The middle roller groove forms a "sub-tooth" drive with the inner pattern hinge ring, which reduces the slip of the lower rubber ring (the slip rate of the upper rubber ring in the inner pattern is 1.66%, and the other rubber rings are 1.75%-2.26%; Slip rate of rubber ring under inner pattern 1.45; Other rubber rings are 1.6-1.8%.) To ensure uniform running speed. Because of the peak concave reason of the pattern in the rubber ring, when the rubber ring under the inner pattern runs on the roller, the front end of the lower pin rod increases the chance of air intake, resulting in an "air cushion effect", so that the rubber ring does not adhere to the movement and does not beat, reduces the movement resistance of the curvature radius of the pin rod, and improves the linear speed uniformity rate of the upper and lower rubber ring. The speed uniformity of the rubber ring is increased, the slip rate is reduced, and the running speed of the rubber ring is close to the line speed of the middle roller. Compared with the smooth rubber ring with large slip rate, the running speed is higher, so the draft multiple in the front area is correspondingly reduced, when the feeding yarn and other conditions are unchanged, the unevenness square of the drafting force is positively linear related to the draft multiple, and the unevenness of the drafting force is reduced, which is conducive to normal drafting, thereby improving the yarn dry. Practice has proved that the spinning quality of the inner pattern rubber ring is better than that of the smooth rubber ring. The experimental comparison is shown in Table 3 and Table 4.
Table 3 Spinning comparison of inner pattern rubber ring and smooth rubber ring
Table 4 Comparison of spinning quality of inner pattern rubber ring and smooth rubber ring
The experiment shows that the use of inner pattern rubber ring is beneficial to improve the evenness of yarn.
2.8 Wear resistance of rubber ring
The rubber ring must have certain wear resistance. Poor wear resistance, easy to appear damage and concave in operation, the inner layer grooving, thus affecting the life of the rubber ring and yarn quality. The early cracking and aging of the rubber ring will seriously affect the yarn drying and the service life of the rubber ring, and the factors causing the aging cracking are: first, the effect of ozone and light makes the rubber ring produce a spider shaped shallow crack; Second, mechanical fatigue causes deep and irregular cracks in the rubber ring. Mechanical fatigue is the main cause of cracking and aging of rubber ring.
source:https://mp.weixin.qq.com/s/Maebd_8Qudc9dXHBDTGFhA