Weft-insertion speed of polyester textured yarns in air jet loom

Saving of energy and expansion of versatility are very important technical subjects for air jet looms (AJL) using profile reeds with sub-nozzle systems. Optimum weft-insertion conditions must be determined for each kind of weft yarn on the basis of the relationship between the airflow in the weft passage and the weft flight behavior. The relationship between weft-insertion conditions and weft-insertion speed of polyester textured yarns was experimentally examined by measurement of the weft tension using a benchmark-testing machine. On the other hand, the weft-insertion speed in AJL was numerically calculated under the consideration that it is a function of the air velocity in the weft-yarn flight path. In the computations, the velocity distribution issued from a circular jet was applied to the equations of the weft motion in the air jet loom as the velocity distribution of the weft passage. From the results, the maximum weft tension increased linearly with an increase in the weft-insertion speed, and also the rate of increase in the weft tension was dependent on the yarn count. Furthermore, of all the weft-insertion conditions, which include the supply air pressure and air injection timing for the main nozzle and sub-nozzles, the main nozzle air pressure most strongly affected the weft-insertion speed. The computational results of weft-insertion speed were in good agreement with experiments using a 16.5 tex / 96 f yarn, it was, therefore, confirmed that the present method of numerical computation for the motion of AJL weft-yarn was suitable.