0 Rumors In the cotton spinning ring spinning system, the draft in the wool spinning project can increase the fiber straightness in the sliver from 87% to 90% to 93%1, which is conducive to improving the evenness of the sliver. However, after the drafting of the roving frame, the yarn quality indicators such as evenness, unevenness in weight, unevenness in strength, and miscellaneous deterioration have deteriorated. Because of the defects of the traditional roving frame structure, the details of drafting and winding mechanisms that are not synchronous with each other during the switching of the car greatly affect the single yarn non-uniformity, the uneven weight ratio, and the broken end rate of the yarn to form a strong weak loop of the yarn. The Japanese textile industry believes that the quality of the spun yarn and 80% of the breakage rate are determined by the quality of the roving. Therefore, improving the quality of the roving frame is the key to improving the quality of the roving and the quality of the spun yarn.
The new type of cotton spinning roving machine adopts a suspension flyer, and the upper ribs of the bearing flyer are fixed to separate the spinning system of the roving frame from the winding system. Once the roving breaks, the airflow generated by the high-speed rotation of the flyer no longer impinges on the roving. The fibers will not float and produce a large number of yarn defects. Suspended flyers create the conditions for high speed, large packages and automation of roving frames, and their electromechanical integration has been greatly improved. The new type of cotton roving machine adopts four roller or three roller double aprons for drafting, together with high quality spring cradle or pneumatic cradle pressurization and efficient and reliable top and bottom roller cleaning systems, improving the work quality of the drafting system and reliability. Multi-motor drive roving machine controlled by computer or inverter motor or servo motor eliminates the traditional gear change mechanism, forming mechanism and most process change gears. The roving machine operating speed 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 in order to maintain a variable frequency or servo motor to drive the drafting roller, flyer, bobbin and lifting mechanism respectively. The process speed of the ingot can reach up to 1500r/nin due to the drafting and winding mechanism. Driven by a separate motor, when the vehicle is shut down, the winding mechanism is stopped first, and the drafting mechanism is stopped afterwards. The roving between the front roller and the flyer is slackened slightly, and then the tension becomes normal again when driving, which can fundamentally prevent the vehicle from shutting off. The occurrence of details.
The new type of cotton spindle suspension roving machine has been used in China's textile mills for more than 20 years. Many factories have carried out the spinning process exploration and gained some experience. However, most of the plants still use the traditional technology of supporting spindle roving machines, which affects the new type. Roving machine normal use and potential play. The author tried to throw a brick to introduce the design of the new roving machine, combined with the spinning process, put forward some superficial views for discussion.
1 Roving tension and "constant tension spinning"
In order to achieve normal winding, the ratio of the take-up speed of the roving bobbin to the output speed of the front roller should be slightly greater than 1 and remain stable during a doffing process. The difference between the winding speed and the front roller output speed determines the winding tension. In the spinning process, the tension is not yet sensed and measured, but the size can be indirectly reflected by the roving section between the front roller clamp and the false twister. This section of roving tension can be measured visually, feel, measured by a linear camera sensor (CCD), or indirectly reflected by the elongation of the roving. This section of roving tension is called the spinning tension or is customarily 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 diameter of the spinning yarn are below the false twisting point. Friction wrapping angle, roving strips and the friction factor between the flyer and false twisting devices and other factors.
After the ratio between the winding speed and the front roller output speed in the spinning process is determined, the winding tension is generally considered to have been determined, but the spinning tension can be obtained by winding the roving at different numbers in the press pocket; the roving is at the position of the spindle bar yarn guide hole The different (14 or 3/4 circle) twigs are adjusted differently. 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 very small, the amount of roving sag is large. At this time, the roving has very low strength, its elongation is large, and the bars are worsened. On the contrary, When the false twisting effect is good and the elongation of the roving is not high, the new type of cotton spinning roving frame uses four-roller drafting and uses a high-efficiency polyurethane (PU) false twister to use a large amount of winding in a certain range. The tension not only does not increase the elongation, but on the contrary increases the false twist effect due to the increase of the winding tension, so that the elongation of the yarn that is most likely to be accidentally stretched, and the elongation is reduced, and the winding is obtained. The effect of density increase is that the new type of cotton spinning roving machine adopts large winding tension spinning, which is the biggest difference from the spinning process of the roving machine.
As we all know, roving in a doffing spinning process, from the small yarn to the large yarn, the winding tension of the roving must be changed from large to small to meet the roving process requirements, it will not happen to yarn. The traditional roving machines with cone or toothed chain continuously variable transmission (PV) as the transmission mechanism all adopt the modified cone or cam curve and are supplemented with a mechanical or electrical tension control system to achieve the volume during spinning. The multi-motor drive (computer) roving machine is embedded in the mathematical mode of the CPU and supplemented with a tension fine-tuning control system (CCD) to achieve a large to small winding tension in the spinning process. the goal of. So "constant tension spinning"
Does not meet the roving winding process requirements, its formulation is debatable.
(As the radius of gyration increases), the centrifugal force of the pressure palm rest decreases with the increase of the winding diameter (because the radius of gyration decreases), so the pressure of the palm decreases with the increase of the winding diameter. In this way, the inner rovings cannot be squeezed out of both ends of the package. “141 is also one-sided, even wrong, because it ignores the technological requirements of the winding tension changes in the spinning process and believes that relying on the “automatic†adjustment of the flyer's palm can avoid the occurrence of yarn jamming. The following tests can be used to illustrate: (1) Pressurizing the weight of the palm and increasing the gyration radius of the palm fulcrum around its fulcrum. Even if its centrifugal force increases and presses the pressure of the palm to the bobbin, it is hoped that the roving can be added to the bobbin. To increase the volume of yarn around the density, there is no change in the amount of yarn contained before and after the test result, that is, no increase in the winding density, and when changing the pressure palm from a non-guided yarn hook to a yarn guide, and appropriately adding the winding tension, Under the premise of appropriate roving elongation, the roving volume is added from the original 4200m. (2) The weight of the pressurizing pawl is reduced until the pressure of the palm is not centripetal when the flyer rotates, ie the “pressure†is negative 41 due to The role of winding tension The roving winding can still be performed normally, so it can be considered that the pressure (pinch force) of the pressure of the flyer pressure on the surface of the bobbin should be the combined force of the following two forces.(1) Winding tension Pulling pressure The pressure of the palm leaf to the tube; (2) The pressure of the palm 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 far greater than the pressure generated by the palm itself. In order to prevent the adjacent flyers from running dry when the roving frame is idle, it is still necessary to ensure that the palm of the press blade can be automatically centripetal at low speeds (eg, 400 rmn).
The front roller does not have a jaw area at the jaws. Xiao Wei is not satisfied with the ishingH cotton roving machine because of the high-speed spine bookmark1 2 The twist factor must be greater than the recommended value in the conventional infeed roving machine spinning process. This is because: (1) The roving package is large and the tension on the roving is increased when unwinding on the spinning machine. Therefore, the roving twist must be added within the allowable range to ensure that the unintentional elongation is reduced when the roving is unwound. (2) The high speed and large package of the new roving machine greatly increase the centrifugal tension of the surface roving of the bobbin. To reduce the broken end of the roving and ensure the efficiency of the roving machine, the twist of the roving must be appropriately increased. Of course, the setting of roving twist must be matched with the sizing of the spun fiber, roving and the drafting ability of the spun yarn. The twisting of the spun yarn will also affect the output of the roving frame. However, in order to increase the yarn quality and the operating efficiency of the roving frame, the twist is still a new type. One of the main features of the spinning process of cotton roving machines.
The new type of cotton spinning roving machine is equipped with an efficient false twister. The method of false twisting is used to increase the strength of the roving between the front roller clamp and the false twist point, narrow the flawless triangle area, and prevent and reduce the accidental elongation of the roving spinning section. Improve roving quality. Here, the concept of “false twist†is introduced: when the roving frame is in normal operation, the 10 cm roving is cut off at the spinning section, and the twist included on the spinning frame can be defined as false twist. False twist is generally from 1 to several times the roving twist, false twist effect is good and false twist is high; false twist size and fiber type, roving weight, spinning tension, guide angle, spindle speed and false twister Factors related to material, shape, size of false twist, etc. Among them, spinning tension is a key adjustable factor.
Before and after the configuration of the bobbin of the cotton spinning roving machine, the corresponding flyers are also arranged in front and rear rows. Since the sliver output from the front roller is longitudinally located on a straight line and is guided to the inlet of the flyer, if the contour ingot is formed, the angle of the front guide yarn is small and the back guide yarn angle is large. The front roller clamp is under the action of the twist. The back row of rovings formed in the mouth of the unblemished triangle is larger than the front row of rovings. The untwisted triangle area is prone to accidental elongation. 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 low front row and high rear row, so that the guide angle is uniform. Yarn angle flyers. The roving machine adopting the three-roller drafting mechanism has a significant effect in the use of such guide angle flyers, because the main drafting area of ​​the three-roller drafting mechanism does not allow the use of smaller collectors, otherwise the rovings will deteriorate. The output roving slivers are wider (generally up to 8mm). The front roller has no longer sloping triangles and the front and rear rows have large differences. This results in large differences in the front and rear rows of roving. However, the modern new type of cotton spinning roving machine mostly uses a four-roller drafting mechanism. In front of the main drafting zone, a bundling zone is added. The smaller collecting device is used in the bundling zone, which does not affect the roving bar. In this case, the roving output must be The width is only about 5mm. After using an efficient false twister, the flawless triangle area is shortened to within 10mm, and the difference between the front and rear rows of the contour flyer is not significant. Therefore, the data of the guideline angle flyers are all four-roller drafting. However, one is a contour flyer, and the other is an equal guide angle flyer. The test data shows that the two have similar effects (different plant elongation tests are only for the purpose).
Table 1 Different types of roving machines for spinning elongation test Model test number Extremely poor elongation % Extremely poor elongation % Yarn yarn Yarn yarn front row Rear row Note: (1) Weifang Ermian, FA431 type roving The machine is the guide yarn angle flyer, spinning C14.6tex (2) Chongqing Sanmian, SCFA461 type roving machine is the advanced guide angle blade. The flyer spare parts are added due to different front and rear row flyers; the rear row spindle lift The removal of the lower cleaner is difficult; when the flyer gear is maintained, the upper boom cover must be removed. There have been instances where individual plants have changed the guide angle flyers back to contoured flyers. From the perspective of spinning technology, the length of the roving between the rear-row flyer twister and the front roller jaws of the guide angle flyers is short, the elasticity is reduced, the sensitivity to tension is increased, and the adjustment requirements for the winding tension are increased. When the improper adjustment or false twisting effect is not good, it is not conducive to the improvement of the dryness and the reduction of the difference in elongation. Some textile mills have also found that when a high-speed rotor spun a certain variety of rovings, the strength of the rear row of rovings is lower than that of the front row K. They are easily broken when unwinding on the spinning frame. After changing to the guide angle flaps, the retraction of the rear-blank flyers has decreased. However, there is no difference in the spindle speed of a roving machine, and the roving front and rear row rovings are consistent. The above phenomenon needs to be confirmed and discussed in more spinning practices.
3 spindle speed and "constant centrifugal spinning"
High speed and large packages are the main technical features of the new type of cotton roving machines. At present, the process speed of the new type of roving machine can reach 1200r/mh~ 1500r/min. The effect of a roving package with a diameter of 150mm is not obvious. Table stealing is for the increase of the diameter of the two-barrel roving frame and the increase in the diameter of the roller. The diameter of the winding is reported to be 178mm. The centrifugal force applied to the roving on the surface of the bobbin often exceeds the strength of the roving and breaks off the winding position. The head, causing a large amount of fiber flow, resulting in serious yarn defects. 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 roving strength. The relation between the centrifugal tension and the spindle speed and the winding diameter of a roving with a basis weight of 5g/10m 4 æ»/10cm is shown in the figure. 131. The centrifugal tension with a spindle speed and a large stretched area shall be drawn into 4 zones T. In order to take into account the output and efficiency of the roving frame, the new type of cotton spinning frame including the single-motor transmission roving machine using variable frequency speed regulation and the multi-motor (computer) roving frame are set to reduce the spindle speed after the middle yarn (ie, The electric control system for reducing bobbin rotation speed; under the premise of strong roving strength in the middle yarn, the roving frame runs at a set high speed, and after the middle yarn, the reduction plan of the spindle speed is designed according to the strength of the roving, so as to ensure that Reduce yarn breakage and ensure roving frame operation efficiency. The “neutral yarn†described here is not a certain diameter or winding length. Because the strength of rovings varies with the variety, quantity, twist, and even temperature and humidity of the roving spun yarn, each spinning mill can determine the actual broken end rate data and experience in the spinning process. The formulation of "constant centrifugal spinning" in the roving process is neither scientific nor practical. In order to achieve high spinning efficiency, the roving frame should find out the position of “neutral yarn†and limit the spindle speed (bobbin rotation speed) after the middle yarn, so that the centrifugal tension of bobbin surface roving is less than the strength of the roving. Otherwise, the pursuit of "constant centrifugal spinning" will greatly reduce the output of the roving frame, or a "outlier" high spindle speed will occur in the case of small yarns.
4 Process parameters related to drafting The new type of cotton roving machines mostly use three rollers with four rollers or four rollers. The three-roller double aprons are drafted in two-zone drafting, namely the main drafting zone and the rear drafting zone. The four-roller double apron drafting adds a finishing zone before the main drafting zone. The main features of the latter are: 1) The main draft zone is not provided with a collector. The horizontal width of the slivers is large, and the control effect of the jaws on the fibers is strengthened. The floating zone is reduced, the fiber shift point is advanced and stable, and the dry quality of the roving bar is improved. (2) Reduced deformation by the main puller helps to increase the fiber straightness of the roving strand.
(3) A smaller collector is provided in the finishing area. The output width of the sliver is narrow, and the sag-free triangle area is small. Here, the probability of accidental elongation is reduced, and the difference in elongation and elongation is reduced. (4) The roving hairiness is reduced. After the small collector is used in the finishing area, the sliver output of the front roller is close to a circle, and the twisting degree is transmitted upwards to reduce the flawless triangle area, resulting in an improved roving structure and a significant reduction in hairiness. (5) The drafting of the four-roller double aprons is suitable for the spinning of heavy-weight rovings, which increases the production potential of roving machines. However, the draft of the four-roller double apron adds a roller to the draft of the three-roller double apron, which also brings some disadvantages: (1) The mechanical wave is easy to occur, and the front jaw (second roller) of the main drafting area is a passive roller. One or two roller drive brackets are not designed, manufactured or adjusted properly and are prone to mechanical waves. (2) The upper jaw and the lower jaw of the front jaw of the main draft zone are located behind a roller. When the cleaner is ineffective, it is hard for the diller to catch the flowers and cause serious yarn defects, which poses a great threat to the yarn quality. . (3) Add a roller, plus manufacturing costs and operating costs.
The process parameters related to drafting, such as gauges, spacers, pressurization, drafting, etc., have a wealth of experience for many textile mills.
41 The quantity of rovings and the ratio of draft multiple rovings are compatible with the technological conditions such as the sizing of the slivers and the drafting capacity of the spun yarns. For the roving process, the output depends on the two factors of the ration and the spindle speed, and the weight can be appropriately reduced. The small twist coefficient plus production or relative reduction in spindle speed is beneficial to the stable production of the roving process and the longevity of the roving frame. The setting of the draft multiple of the roving process must be considered together with the drafting ability of the yarn and the quality of the yarn. In general, after the draft is increased by the roving, the ratio of the slow fiber to the fast fiber is added to facilitate the fiber straightening. improve. Increasing the draw ratio of the rovings can reduce the drafting burden on the spun yarns. When the yarns are spun on, the rovings can increase the loss of the strips after the drawing and can be compensated by the smaller drafts of the rovings. The overall effect will be better.
421an Mechanical Wave Problem A new type of cotton spinning frame was drafted with a four-roller double apron. Many factories found a mechanical wave of about 1 cm in the roving spectrum, and a 25 cm~30 spindle speed setting after drawing by a spinning machine. The high speed before the "Yarn" and the slowdown after the "Yarn" slowed down the centrifugal tension of the surface roving of the bobbin less than that of the roving. 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 are about 1 mechanical waves. The roving machines of different countries, different models, and different time of use have mechanical waves of about 1 AN. The causes of the roving machines have not been identified or resolved. A multifactorial comparison test of a certain plant resulted in a tropism conclusion: When the drafting force is added, the frequency of this wave is high; when the drafting force is reduced, the frequency of this wave is reduced. 1AN mechanical wave is a draft wave or mechanical wave, how to solve, I would like to put forward a new type of cotton spinning roving machine 5 spinning technology, in a certain range of large winding tension is appropriate, in order to meet the winding process requirements, in the small yarn to During the spinning of large yarns, the winding tension changes from large to small. Appropriately increasing the twist factor and paying attention to the false twisting effect of the false twister are another feature of the spinning process of the new cotton spinning frame.
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