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Contribution of different hardening mechanisms into tensile strength of carbon and low alloy steels has been evaluated on the basis of analysis of research papers and own experimental studies. It has been found out that solid solution and grain boundary strengthening provide the most contribution to tensile strength of normalized steel, whereas in structural low alloy steel low alloy steel the role of dispersion strengthening is noticed (21,4 %) along with the above strengthening components. It has been shown that thermal and chemical treatment of St5 grade steel leads to around 27,6 % growth of dislocations strengthening in rolled steel in case of accelerated cooling of hot wrought austenite.

The object of the research is to identify the influence of the pitch of the hammers with cutting edges on the determination of the average length of feed, crushed from by-product stem raw materials in hammer crushers. However, a problem was identified such as the lack of an analytical expression for determining the average length of chopped stem feed by a hammer grinder depending on the distance between the edges of adjacent hammers. With a simultaneous change in the angles of the location of the stem with the maximum size in the layer and, using the methods of probability theory for determining the mathematical descriptions of the function of two arguments, in this study an analytical expression was obtained for determining the average length of particles crushed by hammer crushers depending on the distance between the faces of adjacent hammers. Hammers with cutting edges are used to crush feed from by-product stem raw materials. The end working part of the hammer is milled at an angle of 90°, i.e. two cutting edges are processed at the end of the hammer. As a result of the practical calculations, the average length of feed crushed from by-product stem raw materials was determined depending on the parameters of the hammer crusher. From the resulting graph of the influence of the distance between the faces of adjacent hammers on the average length of crushed particles, it is evident that when the distance between the faces of adjacent hammers changes, the average length of crushed particles varies within the range of 36.19...53.39 mm. To verify the reliability of the obtained expression, experiments were carried out on a crusher with a distance between the faces of adjacent hammers of 20 mm. In this case, the average length of the crushed particles was equal to 38.75 mm, and the theoretical value was 40.16 mm. The difference between them was 3.64 %, which proves the reliability of the obtained analytical expression. The conducted theoretical studies with the receipt of an analytical expression, ensuring the determination of the average length of feed, chopped from by-product stem raw materials, is the solution to an important problem in the development of theoretical foundations of chopping machines, significantly affecting the efficiency of mechanization and operation of feed choppers in practice. [ABSTRACT FROM AUTHOR]

The object of the study is to determine the critical impact speed during shell destruction, study crack formation in the shell, and grind the shell. When operating a grinder-mixer-dryer, problems arise such as determining the speed of impact on the shell depending on the height of its fall, the lack of ability to determine the speed of shell fall from certain heights, which complicates planning the operation of the finger shaft. As a result of research, it was found that an auger with knives crushes and moves feed raw materials, and the impact-spreading shaft ensures partial grinding of fragile raw materials and intensive processes of mixing and drying wet feed with uniform filling of the installation hopper. The appearance of cracks on the shell when it falls from a height of 0.15 m has been experimentally recorded. Therefore, this speed of impact of the shell on a metal surface is the critical peripheral speed of the impact-spreading shaft, which ensures partial crushing of the shell. As a result of theoretical studies, an analytical expression was obtained that provides the determination of the shell impact speed depending on the height of its fall. The value of the critical peripheral speed of the fingers of the impact-spreading shaft is determined to be 1.66 m/s. The experimental results showed the effective occurrence of grinding, mixing and drying processes. Moreover, within 15 minutes of operation of the installation, the wet shell was crushed in accordance with the requirements. The uniformity reached up to 90 % within 4 to 6 minutes of its operation, and drying proceeded at a rate of 26.54 % per hour. All this proves the effectiveness of the processes of grinding, mixing and drying wet food, and also confirms the reliability of theoretical research [ABSTRACT FROM AUTHOR]

Reliability consists of four components: failure-less operation, maintainability, durability, and preservation ability. For different machines and different conditions of operation, different combinations of these properties, and differences in how they are balanced and proportioned are essential. For tractors, the most important aspect of reliability is maintainability, while for agricultural machines, durability is most important. Using the example of a ploughshare, the issue of increasing the durability has been studied; a method for calculating the durability of a ploughshare for various types of soils has been described. The use of plasma hardening of the surface of a 65G-steel ploughshare has been proposed; the effectiveness of plasma hardening of soil-cutting parts and its economic feasibility have been proved. Due to hardening to a depth of 1–1.8 mm, the service life of parts increases by 2–3 times; moreover the downtime of expensive machine-tractor units for replacing worn-out parts is reduced.

The article considers the issue of substantiating the distributing working body parameters for a pneumatic grain seeder. Work on the subject matter is mainly experimental in nature and not sufficiently deeply worked out theoretically. Based on computer simulation, the article determines the most preferred layout of the distributor dividing head, establishes a rational form of the reference cone and the location of the outlet pipes. Based on the simulation of the movement of seed grain particles, the individual design parameters of the distributor dividing head are specified. The results of experimental studies are presented confirming the theoretical background.

The paper describes the results of studies of hardening boride coatings obtained during the implementation of the process of self-propagating high-temperature synthesis. These coatings were composite materials based on aluminum oxide and boron. The obtained coatings were subjected to X-ray phase and microstructural analysis, which showed the main components of the resulting compositions and made it possible to assess the thickness and structure of the coating-base metal transition area. The different content of silicon and iron makes it possible to assess the occurrence of surface chemical and metallurgical processes during self-propagating high-temperature synthesis when heating of the base mixture samples on high-frequency current treatment. The expediency of using high-frequency current treatment in combination with the process of self-propagating high-temperature synthesis for better-quality spattering of the hardening coating is shown. The appearance of two areas in the coating with different thickness and structure of the coating is established. [ABSTRACT FROM AUTHOR]