| 摘要 |
This invention relates to an improved alternating twist yarn (25) assembly utilizing a pair of fluid jets. Two air jets (246, 250) are arranged so that the torque direction induced by one is opposite of the other, producing an alternate "s" and "z" twists. There is a bias or backing air pressure that is applied on whichever jet (246, 250) is not being activated, the backing air pressure is a fraction of the air pressure utilized on the activated jet. This is extremely useful in preventing polymer particles, trimer, loose dyestuff, and other debris from becoming lodged in the unused air jet, preventing its subsequent normal operation. The cycling between one air jet (246, 250) to the other has a frequency equal to the speed of the yarn passing between the two air jets (246, 250) divided by the wavelength which is the distance along the yarn where the twist is of the same type, i.e., "s" or "z" and amount.
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