Abstract:

Objective The existing combing theory and research literature do not involve the exclusion rate of fibers of different lengths and its change pattern in the combing process. In order to study the mechanism of the exclusion of different fiber lengths during combing, the concept of "the number of effective combing times" was put forward to provide theoretical and practical basis for the reasonable formulation of combing process parameters and accurate control of the falling rate of different fiber lengths.

Method Based on the movement of fibers during the carding and separation and joining processes of the cotton comber cylinder, the concept of effective carding times of the comber's waste fibers was proposed, and a mathematical model of the relationship between the effective carding times of the waste fibers and parameters such as fiber length, separation distance, and feed length was established. Using Xinjiang upland cotton, combed cotton laps were made through the normal spinning process, and comber experiments were conducted on the FAZY600 comber. The comber waste rate was tested, and the AFIS PRO 2 single fiber tester was used to test the percentage of different fiber lengths in the cotton laps and waste fibers. The exclusion rates of various fiber lengths for the four experimental schemes were calculated. The exclusion rates of various fiber lengths and their variation rules under different comber process parameters such as waste fiber distance, feed length, and feed method were analyzed.

Results Through combing experiments of four different process schemes, the pattern of exclusion of different fiber lengths was obtained, and the following experimental results were obtained. The greater the number of effective carding times led to greater probability of the fiber being caught by the tin during the combing process. The number of effective carding times decreased with the increase of fiber length, that is, the longer the fiber is, the lower the probability of falling during the carding process. When the fiber length was greater than the fiber bundle length outside the mouth of the clamp plate, the probability of the fiber being caught by the tin in the carding process became less. Reducing the feed length, increasing the spacing of the noil and using the backward feed all increased the effective carding times of the noil, thus increasing the probability of the fiber falling during the carding process of the tin forest. During the combing process, the fiber exclusion rate decreased with the increase of fiber length, but the decrease of the fiber exclusion rate was different in different length sections, with a slow decrease in the 4-12 mm section and rapid decrease in the 12-18 mm range. The fiber length in the section above 18 mm slowly decreased to zero. Reducing the feed length significantly improved the exclusion rate of 4-12 mm fiber, but has little effect on the exclusion rate of fibers longer than 12 mm. The fiber exclusion rate of 4-20 mm section was significantly improved by increasing the spacing of noil or using backward feeding.

Conclusion During combing, the exclusion rate of different fiber lengths decreased with the increase of fiber length, with three obvious characteristics of fiber exclusion rate, i.e. slow decrease for fiber lengths of 4 mm to 12 mm, rapid decrease in the 12 mm to 18 mm fiber length range, and zero approaching decrease when the fiber length is greater than 18 mm. When the feed length was reduced, the fiber exclusion rate increased significantly when the fiber length is from 4mm to 12 mm, while the fiber exclusion rate increases little when the fiber length is above 12 mm. The fiber exclusion rate in the 4 mm to 20 mm section is significantly increased by using backfeed or increasing the spacing of the noil.

Key words: cotton combing machine, effective combing times of dropped fiber, fiber length distribution, fiber exclusion rate, combing process parameter