20—THE INFLUENCE OF THE AIR PRESSURE AT THE ROTOR-CLEANING DEVICE OF ROTOR-SPINNING MACHINES ON THE PROPERTIES OF COTTON OPEN-END-SPUN YARNS

The effect of under-pressure at the entrance to the rotor-cleaning device on the properties of cotton open-and-spun yarns is studied in relation to the opening-roller speed, the total draft, and the rotor geometry. It is shown that there are differences in behaviour between the three rotor types studied; these chiefly concern yarn unevenness and imperfection content. The air pressure at the entrance to the rotor-cleaning device influences, to a small extent, yarn elastic characteristics and, to a greater extent, yarn irregularity and imperfection content for one rotor type (type J). The opening-roller speed affects only certain aspects of yarn unevenness and imperfection content for one of the rotors (type F). whereas the total draft, allied to the yarn linear density, is the factor that has most influence on yarn parameters. The presence of an optimum draft zone between about 90 and 100 is confirmed.