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.

This paper presents the interaction system within the mechanical soil processing process, consisting of two large elements, the metal of the tool and the soil. Due to the two main forces acting on the chisel knives—friction and impact with the sandy soil—the wear of these chisel knives was determined. To determine the wear, a stand was used which allowed testing chisel-type knives in laboratory conditions by changing their functional parameters: working depth, angle of the knives to work the soil, working speed, humidity and granulation of the test environment. The present paper presents an application of the Archard-type wear law to the contact between a chisel-type knife and sandy soil (wet and dry sand). The theoretical model regarding the Archard wear coefficient considered three forms of surface damage (shake down, ratcheting and micro-cutting). The sand was considered spherical and rigid and the surface of the knife was flat. The experimental model considered real steel knives with different surface hardness and operation under controlled conditions of sand granulation, humidity, attack angle, depth of penetration and speed of sliding. The theoretical and experimental results highlight the wear behavior of chisel knives (Archard coefficient) in wet and dry sand.

INMATEH Agricultural Engineering is an open access international journal that publishes reviewed original research papers of both experimental and theoretical nature in the following areas: Technologies and technical equipment for agriculture and food industry, Environmental-friendly agriculture, Renewable energies, Technical equipment testing, Environment, Transport in agriculture, others

Compacted and degraded soils pose increasing challenges to agricultural practices, necessitating innovative approaches to soil tillage. This paper evaluates the performance of a vibratory-enhanced moldboard plowing system, designed to improve energy efficiency and tillage quality under compacted and moisture-deficient conditions, typical of low-moisture soils. Field experiments were conducted across four distinct Romanian regions with varying soil types and climatic conditions, all characterized by significant compaction and limited soil moisture. The vibratory system, mounted directly on each plow body, employed sinusoidal oscillations generated by a DC moto-vibrator, to reduce soil adhesion and traction force requirements, thereby lowering fuel consumption. Key parameters including fuel consumption, working speed, soil fragmentation, weed incorporation, and traction force were measured and compared with the conventional plowing method. The results showed enhanced soil fragmentation and more effective residue incorporation, along with notable reductions in traction effort and fuel use at optimal oscillation settings. These findings highlight the potential of vibratory tillage to be used as a soil preparation method for compaction-prone areas, improving the soil structure while increasing operational energy efficiency.

The goal of this study was to analyze the behaviour of chisel knife type penetration in a certain type of sand. A series of penetration tests were carried out with chisel knife type, the answer to penetration depending mainly on nature, shape, size of knife and operating parameters such as speed, depth and working conditions. Tests were conducted in work conditions with wet sand and dry sand and determined force of resistance to penetration of the chisel knife type to a certain depth.