TWIST DISTRIBUTION OF YARNS ON THE AIR-JET FALSE TWISTER

In the previous paper, the twisting mechanism of the air-jet twister was discussed, in which a high pressure air was tangentially ejected to the inner surface of The cell from the small holes to obtain a vortex by which a yarn was twisted. It was recognized that a yarn was twisted by a gyration of yarn in the twister and twist distribution was fundamentally different from that of the false twisting mechanism of frictional type.Twist distribution in a twisting zone arises from different yarn revolutions which are caused by the propagation of the torque from the highly twisted part of the yarn. It is important to notice the positions of the operational point of yarn twisting as it is the point from which the yarn is twisted and as it is also the point by which the direction of twist propagation is decided.In this paper, the balloon revolution were measured in the twisting and untwisting zones, and the twist distribution was discussed under the considerations of operational point of twisting and the dependence of torsional rigidity and viscosity of yarn upon the twist number and the tension.The following results are obtained.1) It is recognized that the revolution numbers of the balloon which were measured by photo cell detector are equal in the whole twisting and untwisting zone.2) In the air-jet twister, the balloon revolution gives also the yarn rotation which twists a yarn, but the whole rotation of the yarn is not always given by the ballooning.3) The theoretical values of the twist distribution, which are calculated by considering the operational point of twisting and untwisting, agree well with the experimental values.