Theoretical justification of the parameters fle­xible screw conveyor for transportation of grain materials

Abstract

Goal. Increasing the efficiency of the functioning of flexible screw conveyors by substantiating the parameters of the improved design of the articulated and sectional working body for transporting loose agricultural materials. Methods. Theoretical studies were carried out using the methods of theoretical mechanics and higher mathematics. Theoretical calculations of the obtained analytical dependencies and construction of graphical dependencies were performed on a PC using developed programs in the Delphi and SolidWorks software environments. Results. To ensure the correct functioning of the hinge assembly, a study of its design parameters was carried out, which provides mutual rotation, the necessary angular displacement of the axes and the absence of jamming. An analytical relationship is derived for determining the arc movement of the ball along both friction surfaces, the speed of movement of each ball along the arc of the spherical sleeve, and the coefficient of practical action of the hinge and the torque on the drive shaft. Based on the obtained theoretical dependencies, a Pascal program was created in the Delphi environment, and calculations and analysis of the change in the efficiency of the hinge mechanism were performed depending on the main design parameters: the ratio of the radii of the ball and the cylindrical sleeve at the point of contact, the angle of deviation of the hinge axes, the angle of the conical surface holes To choose rational design parameters of the sections of the screw working body, computer modelling of the influence of power loads on the corresponding deformations depending on their operating conditions was carried out. Conclusions. It was established that the transmission efficiency ratio has a maximum value within the range of 0.89...0.93 at a radius ratio of 0.2...0.4. To determine the working area of a particular joint, it is necessary to use design parameters in which the value of the coefficient of practical action is not less than 0.9. The calculation shows that increasing the angle of the hole’s cone reduces the mechanism’s efficiency. It is advisable to choose the ratio of the radii of the ball and the cylindrical sleeve as large as possible for constructive reasons, not less than 0.3. The angle of inclination of the conical surface of the hole should be chosen as minimally as possible, taking into account the selected design scheme of the hinge. In the case of using long conveying screws with a significant number of elements, it is advisable to reduce the angles of deviation of the axes (increase the bending radius of the screw) to improve the overall efficiency of the entire conveyor. A sharp bend in the pipe of the working body, even in one place, can lead to jamming the whole mechanism.