For mowing grass during harvesting of hay or haylage, support-free mowers with rotary movement of knives are used mainly, the productivity of which is much greater than segment-finger mowers. Free-cutting cutting apparatuses with rotational movement of knives happen with their rotation around the vertical (rotary) and horizontal (rotary) axes. Mowers that are equipped with rotary cutting devices significantly grind grass, so they are used in mower-grinders and lawn mowers. The purpose of the work is to substantiate the methodology for calculating the structural and kinematic parameters of rotary cutting devices, corresponding to the conditions of their use. The main parameters characterizing the operation of rotary cutting devices are: area, mows than in one revolution of the disk; knife working length; overlapping knives of adjacent rotors; cutting speed. In determining the basic parameters of the rotary cutting apparatus of the mower, the following assumptions were made. It was believed that the angular speed of the rotor and the translational speed of the mower are unchanged, and the movement of the unit is straightforward. In addition, the cutting apparatus performs mowing in a plane parallel to the soil surface, that is, in a plane perpendicular to most plant stems. It is shown that the absolute speed of any point of the knife varies from the maximum value equal to the sum of the peripheral speed of this point and the aggregation speed of the mower, to the minimum - the difference of the above speeds. It was found that the working length of the cutting edge of the knife is directly proportional to the speed of aggregation of the mower and inversely proportional to the angular velocity of the rotor and the number of knives mounted on it. The overlap of the path of the knives of adjacent rotors depends on the radius of the rotor; the number of knives mounted on it and the kinematic mode of operation of the cutting apparatus. Moreover, an increase in the radius of the rotor requires an increase in overlap, and an increase in the kinematic mode and the number of knives leads to a decrease in the overlap between the paths of the knives. The resulting dependence, which allows you to determine the area, mows than in one revolution of the rotor.
On the basis of the engineering practices of the last 3-4 decades, it is known, tested and proven that, while mathematical models provide reliable descriptions of processes, cycles or physical phenomena, in theoretical research the theory of small deviations is comprehensively preferable to any experiment on regulating characteristics. Considering the fact that all parameters and characteristics are sometimes interconnected by nonlinear dependences, it is impossible to distinguish the influence of a specific parameter on the sought-for value, and can be even hazardous if the determinant argument or its derivative has extreme values. The role of mathematic simulation to determine the residual lifetime of the fuel injection equipment of diesel engines was established. It was also noted that for a reliable description of the processes going on in the fuel injection equipment it is advisable to use the method of small deviations. The mathematical model is based on the known physical laws that describe the interdependence of the two groups of parameters: engine variables and performance parameters - both within the groups and between them. The transition of classical differential equations describing the processes of fuel supply and injection taking into account fuel leaks in precision pairs to the equations with small deviations of parameters is shown. An analysis of correlations between the parameters of injection, fuel supply and fuel leakage was carried out and the most influential parameters were found. The influence coefficients are found and correlations between the influence coefficients and the corresponding parameters are constructed. We used the correlations found to describe the influence of the technical condition of precision pairs on the engine performance indicators. The correlations between the change in injection patterns and small deviations of the parameters describing technical condition of precision pairs are also established.
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