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The purpose of this work is to prove the effectiveness of a practical study of the temperature regime for diagnosing bearing assemblies of mechanical transmissions. Using the example of a two-row roller bearing of the rear support of the intermediate shaft of the vehicle transmission, the temperature in the friction zone under different transmission operating modes on a KAMAZ-5320 was calculated. Finite element analysis of temperature fields made it possible to determine the relationship between the temperature on the outer surface of the bearing assembly and the temperature in the friction zone through the coefficient k=0.327. The zone for temperature measurement -the bearing cover is determined and the maximum temperature of its heating is set. Thermal imaging observations confirmed the effectiveness of the developed method of technical diagnostics of bearings.

The work carried out practical testing of the technology of thermal diagnostics of belt gear elements of the grating mill drive of the combine harvester. The basis of the technology is the principle of using the coefficient of the temperature ratio on the surface of the diagnosed unit and temperature in the friction zone, expressed through the coefficient of proportionality of the finite element model. The peculiarity of the thermal diagnostics, in this case, is to compare the temperature in the friction zone with the maximum allowable temperature for the direct contact zone in the mechanical transmission unit. The object of the study is the tensioning roller of the drive of the grating mill of the first stage of the CLAAS TUCANO 580 combine harvester with 6203-2RS TIMKEN bearings. The result of the numerical experiment showed a significant effect on the temperature in the friction zone of the operational parameters - radial force and rotational speed. The use of 3D-modeling made it possible to determine the key parameter of the proposed thermal diagnostics technology - the proportionality coefficient of the finite-element model k=0.489. The temperature of the bearing assembly of the tension roller was measured periodically, using a non-contact method during harvesting in the 2020 season. For the period of regular observations of 128 moto-hours, the value of the maximum temperature growth rate in the friction zone Vτ=0.025 °C/min and the maximum temperature in the friction zone 69.5 °C, taking into account the ambient air temperature, were determined. No failures of the diagnosed unit were found. In the process of application of thermal diagnostics technology, no errors of the first kind are recorded, which indicates the effectiveness of the proposed technology.

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The operability of machine and tool parts is often determined by the state of the working surface. It is on the surface that cracks arise, wear and corrosion processes begin. The presence of defects, the degree and depth of hardening, the level of residual internal stresses, the structure, the nature of the transition to the base material, most often determine the reliability and service life of parts and structures. Based on a critical review of hardening methods, it was found that one of the promising ones is the effect on the treated surface of a plasma jet of different power density. To ensure wear resistance of the working edges, the surface was treated with low-temperature plasma at an indirect arc plasmatron installation. The work investigated the phase and structural transformations after plasma coating on model samples of steel 65G, studied the structure and built microhardness profiles. Optimal parameters of plasma processing of articles are determined: distance from plasmatron -30 mm, rotation speed -10 s -1 , heating time -10 s. The established optimal modes of hardening treatment were used for plasma hardening using the example of an instrument (spiral drills made of steel grades R6M5, R6AM5 and 11R3AM3F2) under production conditions. For all types of drills, it was possible to obtain a hardened layer of 1-1.5 mm deep from the surface. According to the results of metallographic analysis, the microstructure of the hardened layer contained a white, non-etchable in acids zone with a high microhardness of up to 12000 MPa, the depth of which reached up to 0.4 mm; then there was a structure consisting of martensite and residual austenite with a microhardness of up to 9000 MPa. Tests of experimental drills for resistance, carried out in production conditions, showed an increase in their resource by 2 times compared to a tool that did not undergo plasma hardening, confirmed the possibility of multiple regrind within the hardened layer.