Discussion on the spinning process of new cotton roving machine

0 刖 In the cotton spinning ring spinning system, the fiber-spun project can increase the fiber straightness from 87% to 90% to 93%1 by stretching, which is beneficial to improve the uniformity of the strip. However, after the drafting and winding of the roving frame, the yarn quality indicators such as the uniformity of the strip, the unevenness of the weight, the unevenness of the strength, and the nodules tend to deteriorate. Due to the defects of the structure of the conventional roving frame, the details caused by the unsynchronized drafting and winding mechanism of the switch car greatly affect the single yarn unevenness rate, the weight unevenness rate and the yarn breakage rate, and form a weak yarn ring. The Japanese textile industry believes that the quality of the yarn and the breakage rate of 80% are determined by the quality of the roving. Therefore, improving the quality of the roving machine is the key to improving the quality of the roving and the quality of the yarn.

The new cotton roving frame adopts the hanging spindle, and the upper rib of the supporting sling is fixed, so that the roving machine spinning system is separated from the winding system. Once the roving breaks, the airflow generated by the high speed rotation of the lobes no longer impacts the roving. The fiber does not float and produces a large number of veils. The suspended spindles create conditions for high speed, large package and automation of the roving frame, and the degree of mechatronics is greatly improved. The new cotton roving frame is made of four-roller or three-roller double apron, with high-quality spring cradle or pneumatic cradle pressurization and efficient and reliable upper and lower roller cleaning system, which improves the working quality of the drafting system. reliability. The multi-motor drive roving machine controlled by electronic computer for variable frequency or servo motor cancels the traditional shifting mechanism, forming mechanism and most process change gears, and the running speed of the roving frame is further improved. 12, 31. Multi-motor drive roving machine is equipped with tension fine-tuning control The system (CCD device) can detect the amount of roving sag to keep the variable frequency or servo motor drive the drafting roller, the flyer, the bobbin and the lifting mechanism respectively. The speed of the flyer can be up to 1500r/nin due to the drafting and winding mechanism. They are driven by separate motors. When the vehicle is turned off, the winding mechanism stops first, and the drafting mechanism stops, so that the roving between the front roller and the flyer is slightly relaxed, and the tension becomes normal when driving, which can prevent the car from being fundamentally prevented. The details happen.

The new cotton spinning suspension roving machine has been used in China's textile mills for more than 20 years. Many factories have carried out spinning technology exploration and gained certain experience. However, most of the factories still use the traditional technology of the spindle roving machine, which affects the new type. The roving machine is in normal use and potential. The author tried to throw bricks and jade, from the design of the new roving frame, combined with the spinning process, put forward some shallow opinions for everyone to discuss.

1 roving tension and "constant tension spinning"

To achieve normal winding, the ratio of the winding speed of the roving bobbin to the front roller output speed should be slightly greater than one and remain stable during the doffing process. The difference between the winding speed and the front roller output speed determines the winding tension, which is not perceptible and measurable during the spinning process, but its size can be indirectly reflected by the roving section between the front roller jaws and the false twister. The length of the roving can be measured visually, hand-feeled, measured by a line-array sensor (CCD), or indirectly by the elongation of the roving. This roving tension is called the spinning tension or is conventionally considered to be the roving tension. The relationship between the winding tension and the spinning tension: (1) the spinning tension is derived from the winding tension; (2) the size of the spinning tension and the roving below the false twist point at the wrap angle of the ingot sleeve, and the roving pressure at the palm The friction enveloping angle, the roving whisker and the friction factor between the flyers and the false twister are related.

After the ratio of the winding speed to the front roller output speed in the spinning process is determined, it is generally considered that the winding tension is determined, but the spinning tension can be different by the number of rovings in the palm of the hand; the roving is at the position of the spindle guide hole The difference (14 laps or 3/4 laps) of the false tweezer is differently adjusted. Therefore, the winding tension and the spinning tension are both related and strictly different.

The big "1451 is not comprehensive, the simplest example is: when the spinning tension is small, the roving sag is large, the roving strength is very low, the elongation is large, and the strip is deteriorated. The false twisting effect is good, and the elongation of the roving is not large when the roving is tensioned. The new cotton roving machine mostly adopts four-roller drafting, and uses a high-efficiency polyurethane (PU) false twister to adopt a larger winding within a certain range. Tension, not only does not increase the elongation, on the contrary, due to the increase of the winding tension, the false twist effect is added, so that the elongation of the yarn which is most likely to occur unexpectedly, and the elongation is reduced, and the winding is obtained. The effect of density addition. The new cotton spinning roving machine adopts large winding tension spinning, which is the biggest difference from the spinning process of the spindle roving machine.

It is well known that in a doffing spinning process, from small yarn to large yarn, the winding tension of the roving must be changed from large to small to meet the requirements of the roving winding process, so that the yarn does not occur. Conventional roving frames with a cone or toothed chain continuously variable transmission (PV) as the shifting mechanism are wound with a modified cone or cam curve and a mechanical or electrical tension trimming control system to achieve the spinning process. The purpose of the tension is from small to small; the multi-motor drive (computer) roving machine is implanted into the mathematical mode of the CPU, and supplemented by a tension fine-tuning control system (CCD) to achieve the winding tension during the spinning process from large to small. the goal of. Therefore "constant tension spinning"

It does not meet the requirements of the roving winding process, and its formulation is debatable.

(Because of the radius of gyration), the centrifugal force of the pressing rod is reduced as the winding diameter is increased (due to the reduction of the radius of gyration), so the pressure of the palm is reduced as the winding diameter is increased. Thus the inner layer of roving is not squeezed out of the ends of the package. “141 is also one-sided, even wrong. Because it ignores the process requirements for winding tension changes during spinning, it is believed that the “automatic” adjustment of the palm press can avoid the occurrence of yarn. It can be explained by the following tests: (1) the weight of the pressing cap and the radius of gyration of the pressing palm about its fulcrum, even if the centrifugal force increases and the pressure of the palm leaf on the bobbin is large, it is desirable to roll the roving The density of the yarn is increased by the density, and the yarn yield before and after the test results is not changed, that is, the winding density is not increased. When the palm is changed from the non-guide yarn hook to the yarn guide hook, and the winding tension is moderately added, On the premise that the roving elongation is appropriate, the roving yarn capacity is increased from the original 4200m (2) the weight of the pressure palm is reduced to the center of the palm when the flyer is turned, that is, the "pressure" is negative 41, due to The effect of the winding tension can still be carried out normally. Therefore, it can be considered that the pressure (squeezing force) of the pressing of the flyer to the surface of the bobbin should be the combined force of the following two forces. (1) Winding tension The pressure of the palm leaf pressing against the bobbin; (2) the separation of the palm rest The pressing force of inertia palm leaf against the pressure of the bobbin surface.

The test shows that the pressure generated by the former is much greater than the pressure generated by the palm itself. In order to prevent the adjacent flyers from being pressed around when the roving frame is running empty, it should be ensured that the palm blades can be automatically centered at lower speeds (eg 400 rmn).

The front roller grips are innocent and the small Wei Wei is not the ishingH cotton spinning roving machine. Because of the high speed of the thorny bookmark1 2, the twist and false twist 捻 coefficient must be larger than the recommended value of the traditional roving roving spinning process. This is because: (1) the roving package is large, and the tension of the roving is increased when unwinding on the spinning frame, so the roving twist must be added within the allowable range to ensure the accidental elongation when the roving is unwound. (2) The high speed and large package of the new roving frame greatly increase the centrifugal tension of the roving on the surface of the bobbin. In order to reduce the roving breakage and ensure the efficiency of the roving machine, the twist of the roving must also be moderately added. Of course, the setting of the roving twist must match the spinning fiber, the roving quantity and the drafting ability of the spun yarn. The twisted yarn twist will also affect the output of the roving frame, but in order to improve the yarn quality and the roving machine operating efficiency, the large twist is still a new type. One of the main features of the spinning process of cotton roving machine.

The new cotton roving machine is equipped with a high-efficiency false twister, which uses the false twist method to increase the strength of the roving between the front roller jaw and the false twist point, and reduces the flawless triangle to prevent and reduce the unexpected elongation of the roving spinning section. Improve the quality of the roving. The concept of "false twist" is introduced here: when the roving machine is in normal operation, the 10 cm roving is intercepted in the spinning section, and the twist contained thereon can be defined as false twist. The false twist is generally one to several times the roving twist, and the false twist is good, the false twist is high; the size of the false twist and the fiber type, the roving amount, the spinning tension, the yarn guide angle, the spindle speed and the false twister The material, the shape, the diameter of the false twist, and other factors are related, and the spinning tension is a key adjustable factor.

The cotton roving machine bobbin is arranged before and after, and the corresponding flyers are also arranged in front and rear rows. Since the strips from the front roller are longitudinally located on a straight line and are led to the inlet of the flyer, if the contour is equal, the front guide yarn angle is small, the rear guide yarn angle is large, and the front roller clamp is under the action of twist. The roving in the innocent triangle formed at the mouth is larger than the roving in the front row. In the innocent triangle area, accidental elongation is easy to occur. In order to reduce the difference in the elongation of the front and rear rows of rovings, the upper part of the rear row of the flyers is raised to form a front row of low and rear rows, so that the guide angles of the front rows are uniform. Yarn angle flyer. The roving frame using the three-roller drafting mechanism has a more effective effect on the use of the same yarn guide angle because the main drafting zone of the three-roller drafting mechanism does not allow the use of a smaller aggregator, otherwise the roving strip is deteriorated. The output of the roving strip is wider (generally up to 8mm), the length of the frontless roller triangle at the front roller jaw is longer, and the difference between the front and rear rows is large, resulting in a large difference in the elongation of the front and rear rows of rovings. However, most of the modern new cotton roving frames adopt the four-roller drafting mechanism, and a bundling zone is added in front of the main drafting zone. A small aggregator is used in the bundling zone, which does not affect the roving bar. At this time, the output roving bar is required. The width is only about 5mm. After using the high-efficiency false twister, the flawless triangle is shortened to less than 10mm. The difference between the front and rear rows of the contour is not large. Therefore, the data of the equal-lead angle flyers are all four-roller drafting. However, one is a contoured flyer and the other is an isosceles angle. The test data shows that the effects of the two are similar (different factory elongation tests are different, only).

Table 1 different specifications roving machine spinning elongation test model test number elongation is very poor percentage points elongation is very poor percentage points large yarn medium yarn small yarn front row rear row Note: (1) Weifang two cotton, FA431 type roving The machine is an equal-conductor angle flyer, spinning C14.6tex (2) Chongqing Sanmian, SCFA461 roving frame is equal height and equal guide angle. The flyer is added with spare parts for the front and rear rows of the flyers; High makes it difficult to remove the lower cleaner; when the flyer gear is being serviced, the upper dome cover must be removed. There have been instances where individual plants have changed the length of the guide yarn to the same height. From the perspective of the spinning process, the length of the roving between the rear-spindle false twister and the front roller jaw of the equal-guide yarn corner is short, the elasticity is reduced, the sensitivity to the tension is increased, and the adjustment of the winding tension is required to be improved. When the adjustment is not good or the false-twist effect is not good, it is not conducive to the improvement of the strip and the decrease of the difference in elongation. There are also textile mills that find that when a certain type of roving is spun in a high-speed spindle, the strength of the rear roving is lower than that of the front row K when it is unwound on the spinning frame. After switching to the equal-lead angle flyer, the rear-end flyer unwinding is reduced. However, there is no difference in the speed of a roving machine. The roving of the roving is consistent before and after the roving. The above phenomenon needs to be confirmed and discussed in more spinning practice.

3 spindle speed and "constant centrifugal spinning"

High-speed and large-volume is the main technical feature of the new cotton roving machine. At present, the speed of the new roving machine can reach 1200r/mh~ 1500r/min. The diameter of the roving package is 150mm. The table thief is a two-clock roving machine test ish willow diameter increase and the ascending roll diameter is the book2 178mm. At this time, the roving wound around the surface of the bobbin is subjected to the centrifugal tension which tends to exceed the roving strength and the winding portion is broken. The head causes a large amount of fiber to flow and produces a serious yarn defect. Therefore, increasing the spindle speed to increase the output of the roving frame is not only restricted by the mechanical factors of the roving frame, but also by the strength of the roving. The relationship between the centrifugal tension of the roving of 5g/10m twist 4捻/10cm and the spindle speed and winding diameter is as shown in the figure. 131. The centrifugal tension is increased with the spindle speed and the coiling zone. Fiber blaster bliSh line discussion In order to balance the output and efficiency of the roving frame, the new cotton roving frame includes a single motor drive roving frame and a multi-motor (computer) roving frame using variable frequency speed regulation, which are set to reduce the spindle speed after the medium yarn (ie The electric control system for reducing the speed of the bobbin; the medium yarn is previously operated at a set high speed under the premise that the roving strength can withstand, and the lower speed of the roving is designed according to the strength of the roving to ensure the possible Reducing the break of the large yarn and ensuring the efficiency of the roving machine, the "medium yarn" described here is not a certain diameter or winding length. Because the roving strength varies with the fiber type, quantitative, twist and even temperature and humidity of the roving, each textile mill can be determined according to the measured breakage rate data and experience during the spinning process. The introduction of "constant centrifugal spinning" in the process of roving and doffing is neither scientific nor practical. In order to achieve higher spinning efficiency, the roving frame should find the position of the "medium yarn" and limit the spindle speed (bobbin speed) after the medium yarn, so that the centrifugal tension of the surface roving of the bobbin is less than the strength of the roving of the variety. Otherwise, the pursuit of "constant centrifugal spinning" will greatly reduce the output of the roving machine, or the "extraordinary" high spindle speed will occur in the small yarn.

4 Process parameters related to drafting Most of the new cotton roving frames are drafted with a three-roller or four-roller double apron. The three-roller double apron is drawn into the two-zone drafting, that is, the main drafting zone and the rear drafting zone. The four-roller double apron drawing is added to the finishing zone before the main drafting zone. The main features of the latter: 1) The main drafting zone is not provided with aggregator, the transverse width of the strip is large, the control effect of the jaws on the fiber is strengthened; the floating zone is reduced, the fiber shifting point is moved forward and is stable, and the dry quality of the roving strip is improved. (2) The reduction of the main stretch deformation is beneficial to increase the straightness of the roving strand fibers.

(3) A small aggregator is arranged in the finishing area, the output width of the whisker is narrow, the triangle of the flawless triangle is small, the possibility of unexpected elongation is reduced here, and the difference between elongation and elongation is reduced. (4) The roving hairiness is reduced. After the small aggregator is used in the finishing area, the strip of the front roller output is close to a circle, and the twist is transmitted upward to reduce the innocent triangle area, resulting in an improvement in the roving structure and a significant reduction in hairiness. (5) Four-roller double apron drafting is suitable for the spinning of heavy-duty roving, which improves the potential of the roving machine. However, the four-roller double apron drafting has a more roller than the three-roller double apron. It also has some disadvantages: (1) mechanical waves are prone to occur, and the front jaw (second roller) of the main drafting zone is a passive roller. One or two roller drive brackets are designed or manufactured improperly and are prone to mechanical waves. (2) The upper and lower rollers of the front jaw of the main drafting zone are located after a roller. When the effect of the cleaner is not good, the two rollers are difficult to find, which will cause serious yarn defects and pose a great threat to the quality of the yarn. . (3) Adding a column of rollers adds manufacturing costs and operating costs.

There are a lot of experience in the setting of process parameters related to drafting, such as gauge, spacer block, pressurization, drafting distribution, etc., and I will not repeat them here. Two comments are proposed here for discussion.

41 Quantitative roving and drafting multiples The roving should be calibrated to the process conditions such as the weight of the cooked strip and the drafting ability of the spun yarn. For the roving process, the yield is determined by the two factors of quantification and spindle speed. The small twist factor plus the output or the relative reduction of the spindle speed is beneficial to the production of the roving process and the improvement of the life of the roving frame. The setting of the draw ratio of the roving process must be considered in combination with the drafting ability of the spun yarn and the quality of the yarn. Generally, after the roving is increased by the draw ratio, the ratio of the slow fiber to the fast fiber is added to facilitate the fiber straightness. improve. The roving drafting multiplication is increased, and the drafting burden of the spun yarn can be reduced. When spinning the fine yam, the roving increases the loss of the post-draft deterioration, and the spun yarn can be compensated by the smaller drafting of the spun yarn. The overall effect will be better.

The 421an mechanical wave problem is a new type of cotton roving machine with four-roller double apron drafting. Many factories have found a mechanical wave of about 1 cm in the roving spectrogram, and 25 cm~30 after drawing by the spinning frame.The setting of the spindle speed should be the high speed before the "medium yarn", and the speed of the "medium yarn" will gradually decrease, so that the centrifugal tension of the surface roving of the bobbin is less than the roving strength. The four-roller double apron drafting device can reduce the roving hairiness, improve the roving structure and increase the roving machine production potential, but there is 1