Stanko A. Justification of parameters of screw mechanisms with elastic changeable surfaces for transportation of seed grain materials

The thesis is devoted to the theoretical foundations and new technical support for solving the scientific problem, which consists in reducing the degree of damage to seed grain materials during transportation by screw conveyors by developing new variable screw working bodies with elastic surfaces and choosing rational design parameters and modes of their operation. A structural synthesis of screw working bodies with elastic surfaces was carried out in order to reduce damage to grain materials during transportation by screw conveyors in comparison with traditional rigid screws, using morphological analysis with hierarchical grouping of structural features. Several designs of screw working bodies corresponding to the purpose of synthesis were obtained, for which patents of Ukraine for useful models were obtained, in particular with a brush-like helical part, with a peripheral elastic brush-like part, with a continuous chamber-like part. Theoretical studies of the deformation of elastic brush-like screw working bodies fibers during the transportation of grain material have been carried out. The differential equation for the mean line of several fibers deformation of an elastic brush-like screw working body of a horizontal and inclined screw conveyors with a low-speed mode of operation was derived and solved numerically. Theoretical studies of the parameters of the interaction of the fibers of the elastic brush-like screw working body with the grain material have been conducted. The equation of the grain equilibrium at the initial contact moment with the fibers of the elastic brush-like screw working body is derived. The contact angle between the grain and the fiber of the screw working body is determined. An equation is derived for finding the permissible external load on the grain, at which the amount of fiber deflection does not exceed the limit value at which the transportation of the grain material is ensured. The condition of grain chocking between the fibers of the elastic brush-like screw working body and the inner surface of the casing is determined. The critical angle of contact between the grain and the fiber and the critical distance between the centers of the fibers of round cross-section, at which the chocking of the grain occurs, were determined. A prototype of a screw conveyor with the possibility of using different casing diameters and variable screw working bodies with elastic surfaces was designed and manufactured. The results of experimental studies of three different types of screw working bodies with elastic surfaces are presented. For the screw conveyors with variable screw working bodies with elastic surfaces empirical equations for determining productivity and degree of seed grain materials damage during transportation are derived, which is based on the experimental results statistical processing with the help of application software. The developed designs of screw conveyors equipped with screw working bodies with elastic surfaces and other types of screw conveyors are protected by nine patents of Ukraine for useful models, and the screw conveyor with an elastic brush-like surface, manufactured on the basis of Ukrainian patent No. 150968, passed successful industrial tests in Country agricultural scientific and production farm "Koval". The annual economic effect from the use of the experimental sample amounted to 6,870 UAH.