The Research On Double-shed Weft Insertion System For Air-jet Loom With Constrictors

There are some problems to use the single-shed weaving method in the air-jet loom,for example,the weft insertion rate couldn't be further enhanced,the special product such as velveteen fabric couldn't be weaved,the high cost of the loom may be required. In order to overcome these deficiencies,a system of air-jet loom with double shed and double-flow tunnel was designed,namely, using the"main nozzle + auxiliary nozzle + constrictors"as the relay weft insertion method,it can insert two wefts per turn of the loom,it realized that the air-jet lomm can weave with double shed and double-layer fabric simultaneously,then the above problems of the current air-jet loom were solved.The following aspects were mainly researched in this paper.First,according to introducing the development trends and some other aspects about the air-jet loom,proposed that we must follow own path and design the new insertion method to raise the efficiency and weaving scope of air-jet loom. Second,the jet weft insertion technology and the basic theory of knowledge were introduced.Third,the overall design of the weft insertion system was given. The basic principles for the double-shed and single-shed jet weft insertion system were analyzed;the air system was designed,and it accorded the requirement of the double layer weaving system. Some parts were designed and produced,such as the main nozzle,auxiliary nozzle,onstrictor,reed and so on;the parameters of air-jet insertion system was designed,the process parameters and position size of the mechanism were given.Fourth,the airflow pressure testing system of air-jet loom based on LabVIEW was designed. From the actual application,the data acquisition,processing and image display for the airflow tunnels can accomplish perfectly using the system. Fifth,the airflow pressure for the main nozzle and auxiliary nozzle was tested,the converge airflow pressure of air-jet loom also was tested. The results shows that the airflow pressure decreases with the increasing of the testing distance from the nozzles′exit,pressure attenuation changes rapidly near the main nozzle and changes slowly far from the nozzle,then must use the auxiliary nozzle to complete the relay weft insertion. In addition, at the same place,the converge airflow pressure is greater than converge airflow pressure for the auxiliary nozzle and auxiliary nozzle alone. Through the comparative analysis of the testing results,rationality of the design about the nozzle was verified and a reference data for the improving of the design was offered.Sixth,the simulation for the motion of the beating-up mechanism was compared with the theory result. At the same time,the simulation for the stress of the beating-up mechanism was analyzed. The results indicate that the four-bar linkage beating-up mechanism accords with the requirement of the motion law when weaving the double layer fabric.Breaking the research on the traditional air-jet weft insertion method,the efficiency of the loom was improved,the reference material for design of the main nozzle and the auxiliary nozzle was provided,and the valuable experience for the transformation of air-jet loom in our country was provided.