Видання НТУ "ХПІ"
Постійне посилання на розділhttps://repository.kpi.kharkov.ua/handle/KhPI-Press/62886
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Документ Comparison of cutting tool geometries based on cutting forces and roughness of hard turned surfaces(Національний технічний університет "Харківський політехнічний інститут", 2024) Molnár, Viktor; Szabo, GergelySurface quality and energy consumption are two widely studied topics of hard machining. Due to the increasing need of companies for new, more efficient materials, tools and procedures, their manufacturers or suppliers have to deliver innovative solutions from time to time. In this study the latest development of a hard turning insert manufacturer is used in comprehensive machining experiments to show how the new tool (a wiper insert) behaves compared to its standard counterpart. Based on surface roughness and machining force measurement and analysis, this efficiency is proved by quantitative results: the wiper geometry ensures significantly better surface quality, while the energy consumption of the used machine tool is considerably lower. У токарній обробці загартованих сталей ріжучі інструменти постійно розробляються їх виробниками, і широкий спектр застосування охоплюється різними рішеннями, що стосуються інструментальних матеріалів або геометрії. У цьому дослідженні представлені результати експерименту з механічної обробки. Вимірювали та аналізували шорсткість оброблюваних циліндричних поверхонь та зусилля обробки. Механічна обробка здійснювалася стандартною вставкою, а потім її аналогом після доводки. Мета полягала в тому, щоб визначити,чи забезпечує вставка після доводкименше енергоспоживання за рахунок менших сил різання та сприятливу якість поверхні за рахунок нижчих значень шорсткості поверхні.Документ Probabilistic approach to calculating the rational thickness of the tool's cutting insert for heavy machine tools(Національний технічний університет "Харківський політехнічний інститут", 2023) Klymenko, Galyna; Kovalov, Viktor; Vasylchenko, Yana; Korchma, Dmytro; Boroday, RomanThe paper proves that the development of regulations for the operation of cutting tools on heavy machine tools, the formation of objective functions for optimising the parameters of machiningparts should be carried out based on a given level of reliability of the cutting tool. In this case, a large number of indicators are used to determine the tool's reliability, durability and maintainability separately. Based on statistical and theoretical studies of the probabilistic nature of the properties of the cutting tool and the parameter of load distribution on it, quantitative dependencies between the parameters of the scattering of properties and the thickness of the tool plate of a prefabricated tool were obtained. Thestochastic nature of the machining process on heavy machine tools causes a large dispersion of the properties of the machined and tool materials and other machining parameters. This leads to the need for a probabilistic approach to determining the design and technological parameters of the cutting tool. The reliability of a prefabricated cutter depends on both its load and the bearing capacity of the tool structure, which is the ultimate stress that characterises the strength of the structure. Using a probabilistic approach to calculating the thickness of the cutting plate of the cutters, a correction factor for the thickness was determined taking into account the level of reliability of the tool. The level of reliability was understood as the probability that the maximum stress arising under the action of the load will not exceed the bearing capacity. Typical structures that are most commonly used at modern heavy engineering enterprises were investigated. The law of distribution of cutting forces was determined on the basis of statistical data on the operation of carbide cutters. The thickness of the cutting element was calculated for the Rayleigh load distribution law, determined on the basis of statistical data on cutting forces during turning for different cutter designs. The distribution of the bearing capacity of the tool material of the tool inserts was determined on the basis of laboratory tests.Документ Optimisation of interrupted grinding parameters according to the temperature criterion(Національний технічний університет "Харківський політехнічний інститут", 2023) Novikov, FеdirIn the paper analytical optimization of discontinuous grinding parameters according to temperature criterion is carried out and on its basis conditions for significant reduction of cutting temperature, which consist mainly in increasing the number of contacts of working ledges of discontinuous wheel with fixed cross-section of machined workpiece, are determined. It is established by calculations that providing 20 contacts the cutting temperature may be reduced up to 3 times in comparison with the conventional grinding by a continuous wheel. This is achieved in the conditions of deep interrupted grinding with relatively low workpiece speed, as in the conditions of traditionally used multipass interrupted grinding not more than 6 contacts of working ledges of an interrupted wheel with the fixed cross-section of the workpiece are realized and the cutting temperature is reduced only in the range of 50 %. It is established by calculations that the minimum of cutting temperature at discontinuous grinding is achieved under conditions of equality of lengths of the working shoulder and the notch on the discontinuous grinding wheel and their reduction. It is also established that excess of the length of the working ledge over the length of the notch of the discontinuous wheel leads to insignificant increase of the cutting temperature. This reduces the wear of the discontinuous wheel and increases the machining capacity without actually increasing the cutting temperature. The paper shows that the obtained theoretical solutions are a necessary condition for ensuring a significant reduction of cutting temperature in discontinuous grinding. A sufficient condition should be considered as complete or partial cooling of grinding zone between contacts of machined workpiece with working jaws of discontinuous grinding wheel by intensive supply of effective technological media into the grinding zone.