MOVEMENT OF SOIL PARTICLES ON SURFACE OF DEVELOPABLE HELICOID WITH HORIZONTAL AXIS OF ROTATION WITH GIVEN ANGLE OF ATTACK

Abstract

The article deals with the interaction of a screw cultivator with soil particles. Due to the very wide application in technology, the term "helical surface" is usually understood as the surface of a helical conoid or auger. In this paper, we consider the surface of a deployable helicoid, also linear, but significantly different from the screw surface. The difference lies not only in the geometric shape, but also in the manufacturing technology. If the screw is made by punching or strip rolling with significant deformation of the billet, the unfolded helicoid can be made by simple bending with a minimum of plastic deformation. In terms of theory, if the thickness of the workpiece were zero, there would be no plastic deformation at all when bending it. The working body for soil cultivation consists of a strip of unfolded helical surface, the outer edge of which is sharpened and acts as a blade, and the inner one is rigidly attached to a lattice cylinder. The difference between the radius of the helical line of the blade and the cylinder determines the working depth. The lattice cylinder prevents clogging of the inter-screw space and at the same time performs the additional function of a roller. The body works like a disc tool, that is, the profile of the processed field has protrusions and depressions. At the moment when the moldboard touches the surface of the field, angles of attack and roll arise, similar to the angles of attack and roll of disc guns. The design parameters that provide these angles can be calculated from an analytical description of the surface. The section, that is, the drum with the rotating working surface of the auger, is located so that its axis makes a certain angle with the direction of motion of the unit. This causes an angle of attack and reaction forces that cause the drum to rotate with the surface. From the speed of the aggregate and considering the angle of attack, the angular velocity of the section can be found. The differential equation of motion of the particle after it hits the rotating surface is then generated. The differential equation is drawn in projections on the three axes of the stationary coordinate system. It includes three unknown dependencies: two variables describing the trajectory of the particle sliding on the surface, and the reaction force of the surface. The system is solved numerically. Trajectories of relative and absolute motion of the particle and graphs of changes in its relative and absolute velocities are plotted.