Кафедри
Постійне посилання на розділhttps://repository.kpi.kharkov.ua/handle/KhPI-Press/35393
Переглянути
3 результатів
Результати пошуку
Документ Surface modification of synthetic grinding powders diamond with heat-resistant oxides and chlorides liquid phase application method(Національний технічний університет "Харківський політехнічний інститут", 2022) Lavrinenko, V.; Poltoratskiy, V.; Bochechka, O.; Solod, V.; Ostroverkh, Ye.; Fedorovich, V.The restrictions to the selection of oxides, which may be interesting in the modification of forging heat-resistant oxides of the surface of diamond grinding powders, are defined. It is shown that the first group of the most efficient applied for modifying the surface of the diamond grinding powders includes the following oxides – B₂O₃, TiO₂, SiO₂ and Al₂O₃. The second group, less effective – ZnO, BaO and CaO. To achieve an additional positive effect from the modification it is possible to consider a double modification of surface of diamond grains with a mixture of oxides of the first group and chloride (СаСl₂, NaCl). The process of grain surface modification of synthetic diamond grinding powders by heat-resistant oxides and chlorides of metals and non-metals by liquid phase application has been studied. The structural characteristics of the external structure have been studied and the quantitative elemental composition of the surface of modified powders has been determined. It is established that to achieve a guaranteed increase in wear resistance of diamond wheels when grinding hard alloys at least 2 times it is recommended to modify the surface of diamond grains with a combination of oxides: B₂O₃ grain surface modification (50 % grain) and Al₂O₃ grain surface modification (50 %).Документ The nature of the formation of surface micro-roughness in vibration finishing and grinding processing(Національний технічний університет "Харківський політехнічний інститут", 2022) Mitsyk, A.; Fedorovich, V.The main aspects related to the nature of the formation of surface micro-roughness during vibration finishing and grinding processing are given. It is indicated that the material removal from the surface of the part occurs as a result of the combined action of micro-cutting processes, chipping of metal particles during repeated deformation of the processed surface areas, their fatigue and destruction, the formation, destruction and removal of secondary structures, and adhesion phenomena. It is noted that the real surface after vibration treatment is a set of roughnesses of a certain size, shape and direction. It is defined that the micro-roughness of the surface of the part during vibration finishing and grinding is formed in the form of traces from numerous impacts of abrasive granules on the surface of the part. The largest value of the granule penetration into the processed surface is determined, that makes it possible to characterize the trace from plastic compression in the zone of collision between the granule and the part. The technique and study of the mechanism of formation of surface microroughness is considered. An expression is determined for the normal component of the impact force, which characterizes the main effect on the mechanism of micro-roughness formation. The value of penetration of the granule into the metal of the part is determined. The study showed that the surface micro-roughness during vibration treatment is formed by impacts of granules on the part at different meeting angles. The traces from action of straight and oblique impacts are established. The average height of micro-roughness is calculated. According to the hodographs, the normal velocities of abrasive granules and parts are determined. The average value of the angle of impact of the granules with the part at any point of the trajectory of their movement is also determined. It was revealed that the velocities of granules and parts change in magnitude and direction during one period of the reservoir oscillation, reaching their limiting values, which are proportional to the reservoir movement velocities. The degree of proportionality is expressed by the similarity coefficient for the granule and the part. The average similarity coefficient was also determined by the points of the hodograph. The average values of the movement velocities of the granule and the part in the reservoir are obtained. The minimum and maximum value of the granule penetration into the surface of the part is established. The formulas for the limiting values of the granule penetration depth are given, taking into account the coefficient of ellipticity. The results of calculations for determining the height of micro-roughness of the processed part surface are presented. A formula is obtained for determining the surface micro-roughness during vibration finishing and grinding processing.Документ The methodology of sharpening of blade tools made of superhard materials(Національний технічний університет "Харківський політехнічний інститут", 2019) Fedorovich, V.; Ostroverkh, Y.; Kozakova, N.High durability of the blade tool from superhard materials (SНM), which have unique physical and mechanical properties, creates the prerequisites for its effective use in automated production. However, the widespread use of such tools is constrained by its relatively low reliability during operation. This disadvantage is due to the imperfection of the processes of obtaining SНM: the presence in it residual stresses, internal defects, which appear even after sharpening and thermo-activated finishing. The processes of sharpening of tool blade from superhard materials and cutting with this tool are characterized by high levels of contact pressures and temperatures in the treatment area. Therefore, it seems inappropriate to choose sparing conditions for its sharpening and refinement to ensure the defect of these processes. In connection with this, a new methodological approach is proposed, which makes it possible to determine the cutting conditions and other conditions for sharpening and finishing the SНM blade tool, in which material defects are revealed even at the tool manufacturing stage. To this end, in the software packages COSMOS, ANSYS, NOSTRAN, Third Wave AdvantEdge, thermo-force stress in the cutting edge of the tool simulated under extreme conditions while its operation. This simulations are the initial data for solving the inverse problem – finding conditions (speed, cross feed, normal pressure in the contact) and other diamond grinding modes (physical and mechanical properties of the bond and diamond grains of the wheel, grain size and concentration) according to the well-known stress-strain state cutter from SНM in extreme conditions of its operation. The proposed methodology allows rejecting defective cutters at the stage of their manufacture, thereby increasing the reliability of operation of blade tool from superhard materials.