In the weaving of water jet loom, cotton yarn has been regarded as a non-woven yarn. The action of the gripper in one weft insertion process is changed to two open. Appropriate amount of weft yarn is added before the warp yarn is closed, to reduce the elongation of the weft yarn between the cloth edge and the holder due to the movement of the steel file to the weaving mouth, which can solve the problem that the elongation at break of the cotton yarn is lower than that of the water jet loom. The problem of yarn requirements cannot be woven on the water jet loom. And reasonable allocation of the time of weft free flight and constrained flight, the process of changing the weft yarn from free flight to flight stop from free flight to constrained flight to flight stop, reducing the tension of the weft on the weft insertion side and reducing the latitude The defect rate improves driving efficiency.
The weft insertion of the water jet loom is based on water, and the force generated by the jet of water is used to drive the weft into the shed. Due to the large friction coefficient of water to weft yarn, the traction force of the yarn can be increased, so that the water jet weft insertion has the characteristics of high speed, wide width, low noise and low power consumption. Therefore, it is currently used for weaving of hydrophobic fiber yarn. . The performance of natural fiber fabrics is excellent, and the range of water jet loom expansion has become the consensus of the manufacturers of water jet loom. Through practice, the author successfully weaved pure cotton fabric on the water jet loom, solved the problems of cotton yarn in water jet weaving, and achieved the weaving of hydrophilic fiber yarn with high efficiency and low consumption water jet loom. purpose.
1. Performance characteristics of cotton fiber
China is a large cotton producing country with a wide distribution of cotton and a high yield. Cotton fiber is favored by consumers for its better moisture absorption and breathability. The cross section of the cotton fiber is a tubular waist, and the length of the cavity is about 85% of the total length of the fiber. The longitudinal shape has a rope-like curve, the length is 1000 times to 3000 times the width, and the expansion does not dissolve after water, the elongation at break is 7% to 12%, and the elongation at break (2% elongation) is 74. %, the standard moisture regain rate is 11.1%.
2. Requirements for yarns in water jet loom
The water jet loom relies on the water flow to draw the weft, and the flight of the weft yarn is free. The water flow causes the warp and weft yarns and the fabric in the vicinity of the shed to be wet, and thus is greatly affected by factors such as the variety, state and shape of the shed. Due to various conditions, the conventional water jet loom is mostly used for weaving of yarns with a predetermined moisture regain of less than 10% and an elongation at break of more than 8.8%.
3. Problems and countermeasures when weaving cotton yarn
Since the elongation of cotton fiber is 7% to 12%, the cotton yarn is a non-woven yarn on the water jet loom; secondly, the hydrophobic fiber has less flying flowers, and will not cause parking for no reason due to the flying flower. More, the key parts need to be effectively cleaned.
3.1 Change the opening and closing times of the gripper. The gripper opens to release the weft yarn and start the weft insertion. The gripper closes the weft yarn to end the weft insertion. The gripper is the weft insertion mechanism of the water jet loom. The missing part. Adjusting the relative positions of the gripper cam 1 and the gripper cam 2 controls the length of time the gripper is opened. When the combined large radius of the cams 1 and 2 is pressed against the cam rotor 3, the cam link 4 is driven to swing downward. Since the cam link 4 and the gripper link 5 are fixed on the same shaft, the cam link is The swing of 4 drives the shaft 6 to rotate, and the shaft 6 drives the gripper link 5 to swing upward, and lifts the gripper shaft 8 to lift the gripper movable disc 9 upward, at which time the weft yarn is released. When the small radius of the combination of the gripper cams 1, 2 is turned into contact with the cam rotor 3, the swing lever 4 swings upward under the action of the spring 7, causing the gripper link 5 to swing downward, and the gripper shaft 8 The downward movement of the spring 10 causes the movable disc 9 to move downward, the weft is in a clamped state, and the length of the weft drawn out of the holder cannot be changed. The weft yarn is almost parallel to the steel boring during the weft insertion process. Therefore, when the sling does not hit the weft yarn after the shed is closed, the weft yarn from the gripper to the hem yarn is parallel to the steel sill and the length cannot be changed. When the weft is being driven, the weft pushes the weft yarn toward the weaving direction, at which time the weft yarn from the gripper to the stranded yarn will become the length from the gripper to the weaving position. If the weft yarn is not replenished, the weft yarn is subjected to a large elongation, and the elongation of the cotton yarn is small, which causes the weft yarn to break, so that the weaving cannot be performed normally, which is the key point that the water jet loom cannot woven the cotton yarn. In order to solve this problem, it is necessary to add a part of the weft yarn during the beating process to achieve continuous weaving of the cotton yarn. The relative position of the gripper cam 1 and the gripper cam 2 remains unchanged, the gripper is closed before the reed is hit by the reed, maintaining the proper tension and stability of the weft, and the weft is closed, the weft is in a fully controlled state. After that, the spindle is about 315. When the weft yarn cam 1 is added, the cam rotor 3 is pressed downward, so that the cam link 4 swings downward, and the gripper link 5 is swung upward, and the gripper shaft 8 is pushed upward to move the gripper movable disc 9 to reopen. In the process of beating the steel shovel, the replenished weft yarn is pulled out from the holder to compensate for the problem that the elongation of the cotton weft yarn is small. At the spindle about 340. At this time, the supplementary weft yarn cam 1 is detached from the cam rotor 3, and the holder is closed again to prevent the weft yarn from being excessively drawn, causing other malfunctions.
3.2 Cleaning of cotton yarn hairiness
Due to the short length of the cotton fiber, the surface of the cotton yarn has more fluff and is easy to fall off. Usually, the flying flower falls on the weft feeder, the gripper, the weft detecting head and the nozzle, causing the weft feeder to work abnormally and clamped. The device cannot hold the firm weft yarn, the nozzle works abnormally, and the weft-to-air vehicle is closed. Generally take the method of timely cleaning. Due to manual cleaning, there are often some uncertain factors such as long cleaning period, which causes the effect of flying flowers on the performance of the machine to cause parking. When cleaning, the flying flowers are blown on other parts to cause parking. These factors will have a certain impact on the efficiency of the loom. It is an effective way to solve this problem by adding suction ports in important parts that are prone to fly flowers and achieving timely cleaning. . To configure the suction device, consider the following two aspects: (1) The installation position of the suction port should be appropriate, so as to achieve the purpose of sucking away the hairiness without affecting the state of the jet flow. (2) The selection of wind pressure is closely related to the parameters of the fan, the diameter of the pipe, and the shape of the suction port. When configuring, consider economics and at the same time not affect the stability of the weft movement.
4. Process settings
Taking the 28 tex cotton yarn as an example, the basic options such as the pump form, the cylinder diameter, the pump spring type, the needle form, the nozzle holder, and the needle size are the same as those of the hydrophobic fiber yarn.
4.1 Selection of the first water quantity The cut weft yarn is curved at the head of the nozzle. The purpose of the first water is to straighten the weft head before the holder is opened, and observe the amount of the first water before the end of the free flight. The first amount of water is the least, and the first amount of water is used to ensure that the weft yarn ends are straight. In the process of water jet weft insertion, the cotton yarn is not easy to produce twist due to its large water content, and the medium first water quantity can meet the requirements.
4.2 Setting of the flying angle The strength of the cotton yarn is generally lower than that of the hydrophobic fiber yarn. Choosing a larger flight angle is more suitable for the characteristics of cotton yarn. It can effectively reduce the latitudinal failure of the loom. The start time of the injection is determined by the relative position of the actual injection and the reed. The ejection head is adjusted so that the flight restraint time is adjusted to 5 mm in front of the center of the nozzle. The flight angle of the weft is about 165°.
4.3 Setting the Constraint Flight Time The weft flight is divided into two phases: first, the “free flight” that is firstly flown by the weft yarn stored by the length measuring device, and then the “constrained flight” that measures the long side flight. "Free flight" starts from the opening of the gripper, and the yarn stored on the length measuring drum is terminated instantaneously. The flight speed depends on the speed of the jet stream and the friction coefficient of the weft yarn and the water flow. Relatively high, the average flying speed of the weft yarn exceeds 40m/s under the weaving condition of 140 cm width and 800 r/min; the angle of "constrained flight" can be adjusted according to the weaving requirements of the fabric, and it is the end of free flight to the gripper. The angle between the closures, the speed of which depends on the length of the weft feeder, and the speed is only about 45% of the "free flight". This combination of "free flight" and "constrained flight" is particularly important in cotton weaving. The strength of the cotton yarn is low. If the weft yarn directly transitions from the higher speed at the "free flight" to the speed 0 when the gripper is closed, a large tension is applied to the weft yarn, which frequently causes the weft yarn break in the weft insertion side shed. The combination of "free flight" and "constrained flight", in the weft insertion process, the speed of the weft yarn is first reduced from the higher speed of "free flight" to the speed of "constrained flight", and then this lower The flight speed transitions to a speed of 0 when the gripper is closed, so that the tension applied to the weft yarn is moderated, and the phenomenon of weft insertion due to excessive weft tension caused by closing the gripper is eliminated.
4.4 Determination of Residual Water Quantity From the end of the nozzle jet water flow until the warp yarn is closed, the weft yarn still needs to maintain proper tension to ensure the normal operation of the weaving. At this time, the tension is maintained by the residual water volume. The cotton yarn has a large water content, and the general residual water amount can meet the requirements. The amount of residual water can be judged visually by a stroboscope.
Although the cotton yarn is a hydrophilic fiber, the elongation at break is low and the strength is low. After a slight modification to the weft control mechanism, the cotton yarn can be turned into a woven fiber yarn of a water jet loom. The process setting of cotton yarn weaving, "constrained flight" time is an important parameter that directly affects the latitudinal failure rate. The reasonable choice of "constrained flight" time can reduce the requirements on the strength of the yarn, reduce the weft woven woven, and improve the first-class rate of the product. At the same time, the lower strength cotton yarn can be woven on the water jet loom. The process of mass production of cotton fabrics by water jet looms in textile mills is stable, the quality of finished products meets the requirements, and the export of batch products has been realized. Due to the high water absorption of the cotton yarn, the drying energy consumption after weaving is about 10% higher than that of the hydrophobic fiber yarn fabric, and the elongation at break of the cotton yarn is lower than that of the hydrophobic fiber yarn, and the yarn is broken due to the yarn failure. The table is 2% to 3% higher than the woven hydrophobic fiber yarn. To this end, it is necessary to continuously explore and accumulate experience in future production practices. Weaving cotton yarn with water jet loom can improve the production efficiency of cotton fabric and expand the use range of water jet loom.