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

The paper studies the process of restoration of worn-out parts of agricultural machinery under submerged arc welding, produces definable and determining similarity criteria characterizing the process and discloses their physical entity. The methodology is developed and the criterion equation is received for determining and optimizing the hardness of metal coatings obtained, which is a scientific basis for conducting targeted experiments. An outfit is made for surfacing ploughshares submerged, that allows changing the basic factors without stepwise method. Experimental studies are conducted, as a result of which an analytic form of criteria equation is produced and optimum modes of the recovery of details under gumboil arc welding are established mined in Georgia.

Calculating and increasing the reliability indicators of machines is an important problem as they won’t be competitive in the world market without this high indicator. Currently, many scientists have developed scientific foundations for calculating the reliability of machines, installations, instruments and devices in radio electronics, aviation, space, mechanical engineering and other industries, but such research is not acceptable for agricultural machines that operate in special soil-climatic and dynamic conditions. Their working bodies are constantly subject to alternating dynamic loads, abrasive particles in the cultivated soil, exposure and inclination of the relief, high humidity, high radiation, etc. All these factors cause intensive wear of their working bodies and therefore, such machines are subject to special requirements for reliability. In addition, agricultural machines must have high reliability due to the fact that harvesting is carried out in a short time and failures of such machines lead to significant losses of agricultural products. We have developed theoretical principles and methods for calculating the reliability of agricultural machines, taking into account the specifics of their designs and operating conditions. For this purpose, modern methods of probabilistic-statistical modeling, queuing theory, similarity and dimensions were used. A methodology for calculating reliability was also developed taking into account the structural and logical diagrams of machines and such diagrams of specific machines were drawn up.

The article discusses the designs of small-scale mechanization technical means that are used in Georgia, namely, agricultural machinery installed on moto blocks, the scale and advantages of their use compared to powerful machinery and based on a patent (No. AP 2020 15395), completely new combined aggregate is presented as part of a moto block, which is currently in demand in the context of the development of modern technologies for growing crops on the market. In particular, in small areas and greenhouses. The article proposes a constructive description of the presented combined aggregate and the principles of its operation. Theoretical waste was also carried out using similarity and dimensionality theories. The functional relationship between the optimization parameters and the operating factors is determined and the regression equation is selected, on the basis of which the optimal operating modes are determined.

Adjara, with its diverse natural conditions, relief and soil and climatic features, is one of the distinctive regions of Georgia, dominated by mountainous terrain, steep slopes and small areas. Accordingly, the complex mechanization of agricultural processes by mobile agricultural machinery is inappropriate and therefore small-sized agricultural machinery is used. This technique works in difficult soil-climatic and dynamic conditions, it is constantly affected by significant dynamic forces, high humidity, abrasive particles in the environment, mountainous terrain and others. All these factors cause intensive wear and decrease in the reliability of the working bodies of machines. It should be noted that single and complex indicators of the operational reliability of small-scale mechanization equipment operating in the mountainous conditions of Adjara have not been studied and their establishment will contribute to the rational organization of technical service of small-scale mechanization machines.
The reliability indicators of motoblocks and motor cultivators, such as the probability of failure-free operation, time between failures, the failure rate parameter, the average resource, the coefficients of technical use and readiness, are considered, adequate probabilisticstatistical mathematical models are obtained, the least reliable nodes, types of failures are identified, and a set of measures is outlined to improve reliability

The article examines the single and complex indicators of the operational reliability of agricultural machinery (tractors and combines) operating in the special soil-climatic and dynamic conditions of Georgia, highlights the least reliable units and parts that require constructive improvement.
As a result of research, according to the methodology of probabilistic and statistical modeling developed by us, integral and differential distribution functions of reliability indicators were obtained, their general characteristics were determined, as well as mathematical models and the values of reliability indicators were determined taking into account the distribution law. The adequacy of the probabilistic-statistical models was tested using the Pearson and Kolmogorov goodness-of-fit tests.
As a result of theoretical and experimental studies, characteristic malfunctions and failures of the main units of foreign ag ricultural equipment operating in Georgia have been established, and constructive and technological measures to improve reliability have been developed.

There are described the types of tea bush pruning and working bodies of the pruning devices in the article. Due to the biological condition and agro-technical requirements of the tea bushes, there are carried out five different types of pruning action in the tea plantations. Therefore it is necessary to discuss a different design pruning machines. The variability of the parameters of the cross-section of tea bushes on slope is analyzed, depending on the angle of slope inclination. Also the free line width , as well as the cross-section characteristic parameters of the tea bushes – , ℎ are established.
Different types of surface formation of tea bush are characterized, including flat and semi-cylindrical forms. Their comparative analysis has been conducted. In order to increase their durability and simplifying of the construction of tea pruning and harvesting machines it is recommended to form a flat surface of tea bushes. Accordingly, It is recommended to reconstruct the existing semi-cylindrical shaped tea plantations with flat formation of the bushes surface.