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

The structure of production in agriculture is changing with the change of priorities, both at EU and national level. On the one hand, this is due to interconnection in individual sub-branches, on the other, to the replacement of traditional technologies with new ones. In both cases, this requires the maintenance of more equipment than is necessary for production and the corresponding increase in the cost of production and the reduction of the profit from production. Significant lagging of the machine-tractor fleet renewal processes and increased loading of the used equipment imply intensive physical wear and obsolescence.

Depending on the reasons for write-off, when determining the liquidation value of the machinery, account shall be taken of special features and the possibilities for further use of individual elements (parts, assemblies and aggregates). Several approaches are used to determine the liquidation value:

– the whole machine is considered scrap. The approach is applicable to working machines and attachments to self-propelled agricultural machinery;

– the whole machine is classified as scrap but is dismantled and divided according to the type of scrap (ferrous and non-ferrous metals). The approach is applicable to retractors and attachments to self-propelled agricultural machinery as well as stationary machinery for primary production processing;

– the machine is rated as scrap of ferrous and non-ferrous metals and second-hand spare parts. The approach is only applicable to physically worn machines.

In addition to that, an improved methodology for assessing the liquidation value of different groups of agricultural machinery for moral and physical extinction with and without residual resource elements is suggested.

The efficiency of the machines depends on the completeness of the scope of the indicators and the factors with which they are linked.

In choosing the best solutions, it is necessary to evaluate the system metrics, and the optimal option machine or set of machines to be chosen using optimization criteria.

The indicators for the quality assessment of mechanized works should be divided into common types for all mechanized works and for separate groups of technological processes: soil treatment, sowing and planting, plant care, harvesting of crops.

The system of indicators for the evaluation of agricultural machinery is expressed and evaluated with a large number of properties, indicators and characteristics of quality and reliability.

In general, quality has four groups of properties: feasibility, social, bio-ecological and reliability.

The basic features of calculating the reliability of agricultural machinery are shown, in contrast to industries such as mechanical engineering, radio and television equipment, automation systems and etc., in which machines and apparatus operate in steady modes, while agricultural machines do in difficult soil and climatic and dynamic conditions.

Еconomic aspect of reliability is substantiated and patterns of change in the efficiency of use of agricultural machinery in time are established, the economic parameters of reliability are determined. With the help of the theory of similarity and dimensions as well as the planning of multifactor experiments, through the original installation manufactured by us, the basic physical and mechanical properties of metal coatings are studied, obtained by welding under flux, there are relevant similarity criteria determined that characterize the process of restoration of worn parts and, after processing of experimental data an analytical view of criterion equation is formed and rational modes of the restoration of parts under submerged arc welding are set. Further, to optimize the process, the scheduling theory of extreme experiments has been used and as factors in the regression equation there have been chosen most significant similarity criteria. In methodics elaborated by us, it was obtained an adequate equation and by a method of steep ascent (movement along the gradient), there were determined optimal modes of recovery for metal coatings with high physical and mechanical properties (hardness, wear resistance).

Under these regimes there were recovered worn ploughshares and their operational check showed an increase of resource as many as 1.4…1.5 times. For surfacing worn parts with complex configurations (ploughshare plows, cultivators paws), we have manufactured a special copier allowing to recover the items automatically, in a continuous mode. The feasibility study of the developed resource-saving innovative technology has shown that the restoration of 800 ploughshares provides an yearly economic effect of EURO 1,462.

The article presenting a results about dynamics of moment and coefficient of friction change is established by experimental research of applied layers upon steel parts through vibrating gas metal arc overlaying process with increased wire electrode vibrating frequency. It was established that increasing of the vibrating frequency at rate of 150 Hz leading to significantly shorter time for interaction of both surfaces to obtain a process of established wear.

In the last decade in Republic of Macedonia and the Balkan region, the import and use of modern agricultural machines and equipment has been intensive.

Some makes and models are manufactured by well known brands ,there is also imports of generic construction via a fast manufacturing process.

The trend of developing and perfecting of both is a complex process, and it is rare to find an exclusive distributor. Usually the dealerships do not pay attention to servicing and overhaul or instructions on proper handling during usage.

Because of the wide selection of brands that have been imported, the issues with servicing and overhaul are not resolved on state or regional level which causes problems, delays and expenses during the life span of the machines.

Until now there has not been a strategy made for overhaul centers.

Maintenance of agricultural equipment is carried out by agricultural equipment dealer in Bulgaria. Their business interests forbid them to implement strategies that decrease maintenance costs, such as proactive maintenance or condition based maintenance. For this reason farmers incur unnecessary financial losses. This article shows the necessity and effectiveness of implementing early diagnosis in agricultural equipment maintenance.

The condition of agricultural mechanical engineering and the analysis of the relevant market are given a condition equipment of

farmers by agricultural machinery. Development of KazSRIMEA is shown. Ways of development agricultural mechanical engineering in Kazakhstan are offered

The dynamics of wear index as well as wear resistance changing is established within experimental research of deposited lay- ers upon steel and iron parts. The summary wear index at the end of experimental research of iron parts is about 4 times bigger than the wear index established within steel parts experimental research. The relative wear resistance of deposited layers upon steel parts through vibrating gas metal arc overlaying process is about 10 times higher than layers deposited on iron parts within the same working conditions.

Разгледани са предвидените в законовата уредба критерии за оценка на оферти по Закона за обществените поръчки и са анализирани предимствата и нодостатъците им при провеждане на процедури за закупуване на трактори и самоходна земеделска техника. Разработена е методика за комплексна оценка на офертите по критерия – икономически най-изгодна оферта, базирана на обективни технически и икономически критерии. Така определената комплексна оценка позволява в максимална степен да се отчете влиянието на всеки компонент в нея при запазване на предварително определената му тежест.

The dynamics of moment and coefficient of friction change is established by experimental research of applied layers upon iron and steel parts through vibrating gas metal arc overlaying. It was established that such layers has a insignificant change of the moment of interaction within the period between 4-th and 14-th hour with rate of 5,5 to 6,5 Ncm which is a sign about transition into a period of estab- lished wear regime within shorter time.