Abstract: Rotor To study the influence of the longitudinal tooth pitch of the stationary flats on the spinning quality, the longitudinal tooth pitch and transverse tooth pitch were changed respectively for a spinning test under the unchanged condition of the spinning process and racks. And the quality of the card sliver and the yarn were tested. The results show that when the transverse tooth pitch is sparse from 0.55-0.9 mm and the longitudinal tooth pitch is 1.8-2.8 mm, the IPI value of the yarn does not improve significantly. Its weaker breaking strength of yarn caused embedded impurities. When the longitudinal tooth pitch increases from 1.8-2.8 mm to 2.1-3.4 mm with unchanged transverse tooth pitch, the IPI value of the finished yarn increases significantly; the breaking strength of the yarn increases but the yarn evenness CV value decreases. When the longitudinal tooth pitch is increased to 2.8-3.7 mm, and the transverse tooth pitch is reduced to 0.35-0.7 mm, the IPI value of the yarn is reduced, the breaking strength is increased, and the yarn evenness CV value is improved without embedded impurities. And the nep diameter in the card sliver is reduced. Therefore, in the staple carding process, an increase in the longitudinal tooth pitch and closer transverse tooth pitch is conducive to improving the yarn quality.

Key words: stationary flats rack; longitudinal tooth pitch; transverse tooth pitch; yarn quality