Research On The Movement And Optimization Of The Air-jet Weft Yarn Insertion

Nowadays, the reliability and performance of weft-insertion system of domestic air-jet loomshas been improved greatly with decades of development. But, comparing with foreign advancedair-jet looms, the gap in technology is large. One of the methods to reduce the gap is tounderstand the relationship between the yarn movement during the weft insertion, waving stateof the end of weft yarn and the weft insertion parameters. Therefore, for improving weavingefficiency and optimizing the weft-insertion system of domestic air-jet looms, there is veryimportant theoretical significance and the practical value to study on the topic of this area.In this paper the Titan TT-800air-jet loom was selected as the experimental platform, toresearch and analysis the yarn movement during the weft insertion, on the basis of the yarnmovement during the weft insertion for the sigle nozzle, the main nozzle and auxiliary nozzle airpressure, velocity, synthetic flow distribution center line was measured and analyzed by thegas-flow field test device, the yarn movement during the weft insertion distribution following thechange of distance was focuses studied, following conclusions can be obtained:(1)The main nozzle Jet flow velocity is the effective distance of180-200mm, so from the thirdauxiliary nozzle, the flow of air and the weft traction have no relationship with the main nozzle.The effective jet distance of the auxiliary nozzle is about80-100mm, the tracted region of theauxiliary nozzle is between their own area and the adjacent next auxiliary nozzle area for theweft.(2)In the whole process, the distribution situation of the synthetic flow is as following: Themain jet stream center located at buckle slot which is from the inside6mm place, and the jet flowof the fusing stage for the main nozzle and the first auxiliary nozzle is disorder. The changesituation of the synthetic airflow is closing to the clasp firstly, moving away from the clasp, andthen closing to the clasp again, at last the tendency stop at the2mm place., showing N typedistribution. The synthesis center of each other auxiliary nozzle is close to2mm from8mm,displaying a "V" shaped distribution. The distance with the reed slot is shorter, the fluctuation is small, the weft flow is more stable.(3)Weft in the TT-800air-jet looms has an increasing speed in the whole process. And theacceleration decrease gradually and the acceleration is the biggest when it is at the export ofmain nozzle, the velocity of weft insertion will not increase at the later stage. After the maximumspeed, the velocity of weft insertion will decrease to zero.1)Passing through the main nozzle, there is a initial velocity for the yarn. At this time, the wefttension reaches to the peak value.2)In the whole insertion process, the kinestate of the weft is reduce accelerated motion. Thevelocity of the weft is increasing and the acceleration is decreaseing gradually, weft headsremains the state of tension..3)From the first auxiliary nozzle to the23th auxiliary nozzle, the whole process can beregarded as a repeat process of the cycle acceleration. Yarn is at the state of increasing speed, andacceleration decrease rapidly from maximum value and then suddenly change from increase toreduce. Waving state of the end of weft yarn is smart at first, and then smooth. It is a recyclemotion.4)Between the twenty-third and the twenty-fourth auxiliary nozzle, the main nozzle and thethe former three groups of auxiliary nozzles have already been closed, the quality of the weft inair current field is increasing and the air is only provided by the last three groups of auxiliarynozzles, the traction can not bear to accelerating the flying speed of the weft, after turning240°,only the last set of auxiliary nozzles, then the speed of the yarn will not be increasedbasically.5)Owing the influence of the sensor, the speed of the yarn decreased harply during the stagebetween auxiliary nozzles of24th to25th, and the yarn will stop at a short time, and then thewhole weft process is over.In addition, using the high-speed camera system, the speed of weft ejected from the mainnozzle exit to stop the flight of the weft insertion process was tested and analyzed. The yarnmovement during the weft insertion was accord with the actual state of motion. For theparameter, the pressure of auxiliary nozzle should be slightly larger than the main nozzle.