Research on friction influence on the working process of agricultural machines for soil tillage

摘要

The results presented in this article, refer to a more precise qualitative and quantitative estimation of the friction phenomenon, in the working process of agricultural machines, for soil processing. The positive role of the friction has been taken into consideration, namely to help drive the machinery and to properly disintegrate the soil, as well as the negative role of friction, which generate wear of working tools, high energy consumption and pollution [1, 2]. It is proposed to give a more accurate estimate of the weight of terms expressing the friction, implicitly producing wear, in the formula of the traction force required to pull the agricultural machine. Starting from this information, it is proposed a description of the evolution of wear depending of time, or function of the amount of work performed, as well as criteria for the decision to replace the working tools as worn out. Since 1960, a series of mathematical formulas describing the wear phenomenon have appeared in the literature [1]. The authors [1] identified 182 equations describing the wear phenomenon in its various forms. In this paper we have proposed a mathematical model that is specific to ploughing tools and we attempts to estimate a possible duration of exploitation. The detailed calculation of the possibility of identifying some mathematical models' constants, using experimental data, shows that structural changes are sometimes required. The structural changes of some formulas, made in accordance with other research results in this field, can highlight components of the traction resistance forces useful in detail calculations of some phenomena that accompany the general process being pursued. The fact that the model for estimating the wear of the working tools of the soil processing machinery can well estimate experimental facts encourages the further development of the model by introducing more parameters defining the geometry of the working tools. This opens the way of optimizing the work tools of the machines that work in and with the soil in general. The mathematical model of plough chisel wear proposed also provides a useful tool for determining the end use at which the work tool must be changed. This value can be, for example, that distance xlim, at which the pointed side of the chisels is completely worn out. For the concrete case under consideration, for example, this value is: xlim = 863 km, working distance.