International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

At the Institute of Soil Science, Agrotechnologies and Plant Protection – Sofia (IPAZR – Sofia) an experimental model of a machine for combined soil treatment in permanent plantations has been developed. The machine is designed to work using technology without turning the soil layer and at the same time at a sufficient depth for fruit plantations. Tests were conducted in laboratory and road conditions to verify the capabilities of the structure. Deficiencies have been identified, as a result of which the work must continue.

Rules for aggregating mounted agricultural machines have been systematized. Dependencies are derived for determining the parameters of the tractor after aggregation with the machine and the rules for safe work according to the norms are given.

This is a review of the groups of factors influencing the quality of the main and pre-sowing tillage of the soil for growing tomatoes – soil-climatic, technological.
The paper performs an analysis of the a priori information and from the conducted experimental researches the connection between the separate factors and the quality for performing the basic and pre-sowing treatment of the soil for growing tomatoes was established.

Irrigation plays a key role in growing vegetable crops. The efficiency of irrigation is expressed in obtaining optimal yields in terms of quantity and quality. The use of water resources should be water and energy saving in order to reduce the costs of vegetable production and to be environmentally friendly. The main criteria for assessing the effectiveness of irrigation are the total and additional net incomes. In order to meet the set requirements for irrigation, the best effect is obtained by applying drip irrigation. When growing tomatoes, the value of the irrigation system is redeemed in the first year for areas over 5 dka, for areas below 5 dka it takes 2 years. Drip irrigation of tomatoes has shown that the frequency and size of irrigation rates affect the weight, diameter and length of the fruit, their number and hardness.

In this work the possibilities of reducing the roughness and defects of surfaces obtained by 3D printing with selective laser melting (SLM), via reactive electrospark surface modification (ESD) with low-melting AlSi alloys has been shown. The influence of the energy parameters of the ESD process on the roughness, microstructure, microhardness and performance characteristics of the coatings has been studied. Surfaces with new phases and ultrafine crystal-amorphous structure with particle sizes from micro to nano level, with new relief, with thickness up to 15 μm and microhardness up to 11 GPa were obtained, as the initial SLM roughness from Ra = 8-11μm is reduced to Ra=3-5 μm. Possibilities for control of the characteristics of the coatings and purposeful synthesis of new phases by changing the parameters of the spark discharge have been established. The parameters of the ESD process, which provide simultaneous reduction of SLM surface roughness, removal and erasure of the defects and targeted reactive synthesis of new phases with high performance properties and wear resistance, are defined and optimized.

Mechanized harvesting of tomatoes should be carried out with minimal damage. This is achieved by knowing the processes. The movement of a tomato plant in the period of transition between conveying devices has been studied. Dependencies determining the length of free movement and the rates of fall on the fruit separator are derived, which are essential for determining the kinematic regime and preventing damage to the fruit.

Perennials are an important strategic sector for agriculture in Bulgaria. In order to obtain good results from their cultivation, a scientifically based system for the maintenance of the soil surface is needed. Existing technologies have been analyzed to support the selection of an appropriate soil maintenance system. The size of the agricultural holdings in Bulgaria for the most widespread perennial plantations, which are the vineyards and are substantiated by economically expedient technologies and machines for soil cultivation suitable for the majority of the agricultural producers, is analyzed. The advantages and disadvantages of the technologies and the machines for their realization are presented.