Abstract
Elite seed-production farms must process very small seed-cotton samples, often only 40–85 g per progeny family, without mixing the seed of different families. The saw-type laboratory gin currently used for this purpose (model DL-10) cannot do this reliably. Its working chamber needs 0.5–0.8 kg of cotton to form a stable roll density, so individual family samples cannot be ginned separately, and the saw action raises the mechanical damage of the seed. This article presents a new two-knife roller laboratory gin designed for small samples. The machine combines a rotating textolite working drum, a fixed knife, a reciprocating striking knife, a reciprocating feeding and pressing plank and a grate with adjustable rod spacing. A physical–mechanical model of fibre separation, a kinematic and dynamic description of the striking knife and a second-order differential equation of the motion of the seed-cotton lock are developed. Experiments on a prototype established a drum friction coefficient of 0.45 (rising to 0.6 after wiping with ethanol), a rational drum groove pitch of 40 mm and a grate spacing of 6 mm for small-seeded and 7 mm for medium- and large-seeded varieties. In production-condition comparative tests on 15 kg samples, the roller gin matched the saw gin in throughput (60 kg/h), raised lint outturn from 38.0 % to 38.7 %, reduced the increase in seed mechanical damage from 1.3 % to 0.4 % and cut installed power from 3 kW to 0.7 kW. The expected economic effect is about 181.6 million UZS per laboratory per year, or 544.8 million UZS for three laboratories in one region. The machine was recommended for wide introduction by the testing commission and accepted for use at the BOYOVUT TECHNO CLUSTER laboratory in Sirdaryo region