Evaluation of the uniformity of the stroke depth of the working bodies of the combined slope treatment unit

. Research has found that the parameters of the surface to be treated, the speed of the unit, the lateral movements of the working bodies and the instantaneous center of rotation, due to the redistribution of the gravity of the unit on the slopes, lead to uneven processing depth. To study the characteristics of the change in the stroke depth of the working bodies of the combined unit, according to the results of field experiments, an assessment was made of the uniformity of the stroke depth of the working bodies of the combined unit for


Introduction
Important indicators for assessing the quality of the combined unit are the uniformity of tillage in depth and degree of loosening.
It is not yet possible to ensure perfect uniformity of the stroke depth of the working bodies of the unit, however the deviation from the specified processing depth can be estimated by observance with permissible agrotechnical boundaries.
Modern tillage units do not provide agrotechnical requirements for slope treatment. Moreover, there are cases when, even on slopes not exceeding 6°, the working bodies located up the slope are pushed out of the soil under the influence of external factors.
The uneven depth of the stroke of the working bodies of tillage units has been studied by many researchers, however, it should be noted that research in this area is not yet complete [1,2,3,4]. The theoretical studies carried out by us have revealed the main causes of the uneven depth of the stroke of the working bodies -the shape of the cultivated field and surface parameters, the speed of the unit, the lateral movement of the working bodies and the instantaneous center of rotation of the unit. Under the influence of these factors, the organs located down the slope are additionally deepened, and the organs located up the slope come out of the soil, which leads to uneven cultivation depth.

Material and method of investigation
To study the characteristics of the change in the stroke depth of the working bodies of the combined unit operating on a slope, field experiments were carried out. At various speeds of movement of the unit, the depth of travel of the working bodies working up and down the slope was measured. the average depth of processing and the deviation from the specified value were determined.
According to the measurement results, graphs of the change in the average depth of processing were plotted -depending on the slope of the slope (Fig. 1) and the speed of the unit (Fig. 2).  The experiment was carried out using the experiment planning method, for which the mathematical model of an object or process is presented as a polynomial or, as is customary, a segment of the Taylor series, where it is converted into an unknown function [5,6,7,8].
As independent factors (X), the aggregate speed (V) and the slope slope () were chosen. As an optimized parameter (Y), the average processing depth (aav) was chosen.
The levels of factors and intervals of variation are shown in The transition from the actual value to the code value is carried out using the expression: Where: x i -is the actual value of the i-th factor, X i0 -is the median of the variation interval of the i-th factor, ∆X i -is the variation interval.
An experiment planning matrix for determining the actual depth of travel of the working bodies of the unit depending on the slope (β о ) and the speed of the unit (V) is shown in Table  2. As a result of mathematical processing of experimental data, the coefficients of the regression equation are determined by the following equation: If the calculated value of the confidence interval is less than the tabular value, then this coefficient is excluded from the regression equation.
Based on the data obtained, the following empirical dependence was compiled in the form of a regression equation: The fit of the regression equation was tested the criterion Fisher: The compliance of the obtained regression equation was checked the criterion Fisher [6,7,9,10]: As a result we will have the following: The received value of the Fisher criterion shows that the equation of regression is matching the nature of the problem under study.  An analysis of the obtained regression equation (5) and its graphs (Fig. 3) shows that with an increase in the slope slope () and the speed of the unit (V, km / h), the working bodies travel depth decreases. When processing a slope with a slope of β = 6 0 , an increase in the speed of the unit from 6 km / h to 12 km / h leads to a decrease in the depth of processing from 25.0 cm to 23.6 cm (by 5.4%), when processing a slope with a slope of β = 9,8 0 the stroke depth decreases from 23.4 cm to 22.0 cm (by 5.8%), and with a slope β = 13,6 0 -from 22.7 cm to 21.3 cm (by 6.0% ). This means that with large slopes, an increase in the speed of the unit leads to an intensive decrease in the depth of processing. The same pattern is observed with increasing slope slope. So, increasing the slope from 6 to 13,6 0 leads to a decrease in the depth of processing. At a speed of v = 6 km/h, the working depth decreases from 25.0 cm to 22.7 cm (by 9.2%), at V = 9 km/h -from 24.3 cm to 22.0 cm (by 9.5%), at v = 12 km/hfrom 23.6 cm to 21.3 cm (by 9.8%).

Conclusions
1. It has been experimentally established that an increase in the angle of slope and the speed of movement of the unit leads to a decrease in the average depth of processing.
2. To ensure the uniformity of the depth of processing slopes, it is necessary, if possible, to observe the parallel position of the frame of the unit to the surface to be treated.