The uniformity of the sliver is evaluated by the weight unevenness rate of the 1m piece of sliver and the evenness rate of the 1m piece. Carding machines are used to process cotton fibers and chemical fibers and belong to textile machinery. According to the spinning process, carding is an important process.
The front process of the carding machine is the opening and cleaning machine, and the latter process is the drawing frame (carding process) or the sliver coiler (combing process). During the spinning process of the spinning frame, the semi-finished roving or sliver is drafted, twisted, and wound into a spinning machine. The combed sliver and the needle-carding machine combine the sliver, the needle row is drafted to improve the sliver structure, and the roving is further spun into spun yarn on the ring spinning frame, which is the main spinning machine. The structure of the double twisting unit of the double twisting machine mainly includes the spindle braking device, the spindle part of the double twisting machine, the yarn winding device, and the special device of the double twisting unit.
The development of sliver unevenness mainly depends on the degree of carding, the degree of uniform change in the transfer of fibers to Doffer, the information on the state of machinery and equipment, and the structure of the cotton web. Poor mesh structure, such as severe cloud spots and holes, edge breakage, etc., will worsen the strip unevenness. The reasons for cloud spot cotton net are: bluntness and local damage of Xinjinlong card clothing; too large or inconsistent distance between comb and back cover to Xinjinlong; poor or loose cotton ring feeding; pressure difference caused by deformation of cotton stalk or drum; The bottom leakage is large, the bottom leakage is small, and the hanging flowers are brought into the cotton net from time to time; improper specifications of the card clothing make the fibers filled around the flowers; the flatness of the comb elements is poor; Or carding boards, etc.
Causes of broken holes and broken edges: large and small leaking bottoms and front and rear cover hairs, fiber impurities adhere to the operation; Xilin or Taoist flowers are partially or on both sides; cotton rolls have holes, sticky layers, uneven edges, and bad heads; Excessive accumulation of frame or wall flowers. Others such as Xilin, Daofu, the periodic change of the spacing caused by the vibration of the roller, the position or spacing of the peeling roller is incorrect, the Daofu draft on each part between the rings and the tension of the cotton web are too large, and the quantitative strip is too light, which will increase the strip. Dry unevenly. Generally, the evenness is controlled at 4-18.
Uneven weight of sliver is closely related to uneven weight of spinning. The main reasons for the decline in the quality of the sliver are the uneven lap (or cotton layer), the poor noil rate of each machine of the carding machine, and the poor mechanical condition. Therefore, it is necessary to reduce the unevenness of the cotton roll, eliminate the holes of the cotton roll sticking and the bad joint of the cotton roll.
Unify the process conditions for special yarn carding. Ball drop rates should be tested regularly to reduce differences in ball drop rates between machines. Generally, the unevenness of sliver weight should be controlled below 4%.