The study is aimed at improving the quality and energy indicators of technological processes of soil tillage with needle harrows in the conditions of their application for shallow surface loosening in climatic zones subject to wind erosion.
It is established that the interaction of a needle of any shape and design with the soil leads to the appearance on its surface of a figure close in shape to an ellipse. In this case, in the phase of the needle entering the ground in the direction opposite to the movement, a semi-ellipse is formed, the minor axis of which is equal to the radius of the conical (cylindrical) part of the needle that has penetrated the soil. In the phase of emergence from the soil, the needle on its surface leaves flatness in the form of the second part of the semi-ellipse. The funnel (trace) that the needle forms represents a cone based on an ellipse.
A method was developed for the analytical assessment of the planar-surface and spatial-depth interaction of a needle harrow with soil, which allows increase the accuracy of forecasting technical and operational indicators of the technological process and reduce energy costs for its implementation. The method creates the prerequisites for improving the quality and energy indicators of technological processes of soil treatment with needle harrows, especially in the conditions of their application for shallow surface loosening of soil in natural and climatic zones subject to wind erosion.
It was established that an increase in the angle of sharpening of the needle leads to a corresponding increase in the value of the angle of inclination of its axis to the horizon, at which the contact point of the side surface is farthest from the vertical axis of the deepening of the needle into the soil.
According to the results of the analysis of the surface-plane picture of the interaction of the needle with the soil, it was found that the semi-major axis of the ellipse compared to the radius of the conical (cylindrical) part of the needle deepened into the soil with a sharpening angle of 300 increased by 24%; with a sharpening angle of 450 by 11.7%; with a sharpening angle of 600 by 6%, respectively. The increase in area for this size of needles was at a depth of 4 cm – by 31%, per 6 cm – by 47%, per 8 cm – by 67%, per 10 cm – by 78%, respectively.
An increase in the immersion depth of the needle leads to a corresponding increase in volume, which is due to its contact with the soil. In conditions of deepening the needle with an angle of sharpening 300 from 4 to 10 cm, the volume increases by 2.8 times, and from 4 to 8 cm by 1.4 times. Under conditions of deepening the needle per 8 cm, the largest increase in the volume difference is established by the angle of sharpening 300 – by 9.1 cm3, angle 450 – by 10.8 cm3, angle 600 – by 10.8 cm3, respectively.
Keywords: needle of a harrow, interaction of the needle with the soil, coefficient of surface-plane interaction, spatial-depth interaction.