opening(redirected from Caval opening)
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the removal of foreign matter and defective fibers from cotton and the loosening of the cotton stock; when the process is applied to flax, wool, or other fibers, it is called scutching. Opening is one of the primary production processes in spinning; scutching is one of the initial operations in processing bast fibers. Either is usually carried out after the initial loosening of the material, when the process of beating is most effective in cleaning the material and results in minimum damage to the fibers.
Opening consists of a blow delivered by the working elements of a machine on a layer of fibers held by the machine’s feed mechanisms; the beating action separates the fiber from the foreign matter. Only the largest and least sticky impurities are removed; individual fibers are separated and sticky impurities removed during subsequent carding operations.
Opening is carried out on cotton openers; scutchers are used for other fibers. The basic working members are a drum with cutting, splitting, or beating elements and the beaters. The drums may have smooth, prismatic elements, large pins, saw-toothed elements, or combinations of these types.
In a cotton opener, the loosened cotton stock is fed from the preceding machine to a feed hopper. A control device maintains a constant height of cotton in the hopper, which ensures an even flow of fiber emerging from the machine. The cotton is fed from the hopper by rollers and feed cylinders to a drum, in which blades turn at a speed of 500–600 rpm and strike the cotton layer. Shreds of cotton are torn off and thrown on a grid surrounding the drum, the cotton is additionally agitated, and the freed weed contaminants fall through the grid spaces into waste chambers. A fan sucks air from the mesh drums, creating an air flow that removes the cotton from the drum blades and the grid and carries it to the mesh drums. As the drums rotate, they form a layer of cotton from individual flakes; the layer is removed from the drum surface by cylinders and transported to feed cylinders, which deliver it to the beater. The beater rotates at 900–1,000 rpm and strikes the cotton layer with cleats; the cotton is loosened, and the separated weed contaminants drop through the grid into a waste chamber. A flow of air removes the cotton from the beater cleats and transports it to the next machine.
Scutchers for bast fibers are also equipped with beating drums. The primary working members in wool scutchers are drums with splitting elements. The intensity of processing is determined by the number of blows delivered per unit length or weight of the fiber layer.
REFERENCEMekhanicheskaia tekhnologiia voloknistykh materialov. Moscow, 1969.
V. V. ZHOKHOVSKII