Різання та інструменти в технологічних системах
Постійне посилання на розділhttps://repository.kpi.kharkov.ua/handle/KhPI-Press/62923
Офіційний сайт http://rits.khpi.edu.ua/
У збірнику публікуються наукові статті, у яких висвітлюються актуальні питання в області механічної обробки сучасних матеріалів із застосуванням високопродуктивних технологій, нових методів та вимірювальних приладів для контролю якості оброблених поверхонь і високоефективних різальних інструментів. Висвітлюються аспекти оптимізації й математичного моделювання на різних етапах технологічного процесу.
Рік заснування: 1966. Періодичність: 2 рази на рік. ISSN 2078-7405 (Print)
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Збірник «Різання та інструменти в технологічних системах» включено до Переліку наукових фахових видань України з технічних наук до категорії «Б» згідно Наказу МОН України №409 від 17.03.2020 р.
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Документ Surface temperatures and vacation burns occurring during grinding of cemented gears with two dished wheels on different parts of the machined involute profile(Національний технічний університет "Харківський політехнічний інститут", 2023) Tonkonogyi, Volodymyr; Yakymov, Oleksiy; Bovnegra, Liubov; Nоvikоv, FеdirTo increase grinding productivity with the provision of specified physical and mechanical properties of the surface layer of the surface layer of the processed part it is necessary to know the temperature on the surface of the workpiece, since its value depends on the depth of the defective surface layer. In the work theoretically justified the difference of surface temperatures in the initial (at the base), in the middle (on the dividing circle) and final (at the top) points of involute profile of the gear tooth when grinding with two disc wheels on the zero scheme. The difference in temperature at different points of the processed tooth profile is justified by the fact that at different parts of the trajectory of the movement of the heat source acts a different number of thermal pulses. These pulses have different duration and time intervals between the actions of these pulses in different points of the involute profile are also different. The number of thermal actions on a fixed point of the machined profile depends on the length of the heat source, and the duration of heating of the surface at this point is determined by the width of the heat source. The duration of cooling depends on the location of the point on the involute profile. Mathematical models have been developed to calculate the temperatures at different parts of the trajectory of the rolling path of a disc grinding wheel on the tooth being machined. Each of these formulas contains two sums. The first sum determines the temperature increase at a fixed point of the tooth profile under repeated exposure to thermal pulses during the forward stroke, and the second sum - during the reverse stroke. Mathematical models are based on the principle of superposition of thermal fields. It is found that the temperature in the middle part of the tooth is 40% less than at the tooth apex and 20% less than at the tooth base. The engineering method of distribution of the total allowance by passes at multi-pass gear grinding with two dished wheels according to the zero scheme has been developed. The method is based on the experimental dependence of the depth of the defect layer on the depth of cutting, which has a linear character. In the work, calculations were made on the allowance distribution in the initial, middle and final points of the involute tooth profile. The calculations showed that in order to prevent burns on the final machined surface, grinding in different parts of the machined profile should be performed with a different number of passes. The smallest number of passes on the separating circle, and the largest - on the top of the tooth. The proposed methodology of distribution of allowances by passes can be used at the stage of design of gear grinding operation (for optimization of modes) and at the stage of machining (for diagnostics of the operation). It is theoretically substantiated that calculations of allowance distribution by passes should be made only for the tooth head. To increase grinding productivity with provision of the specified physical and mechanical properties of the surface layer of the processed part it is necessary to know the temperature on the surface of the workpiece, as its value depends on the depth of the defective surface layer. In the work theoretically justified the difference in surface temperatures in the initial (at the base), in the middle (on the dividing circle) and final (at the top) points of involute profile of the gear tooth when grinding with two disk wheels on the zero scheme. The difference in temperature at different points of the processed tooth profile is justified by the fact that at different parts of the trajectory of the heat source acts a different number of thermal pulses. These pulses have different duration and time intervals between the actions of these pulses in different points of the involute profile are also different. The number of thermal actions on a fixed point of the machined profile depends on the length of the heat source, and the duration of heating of the surface at this point is determined by the width of the heat source. The duration of cooling depends on the location of the point on the involute profile. Mathematical models have been developed to calculate the temperatures at various parts of the rolling path of a dished grinding wheel on a machined tooth. Each of these formulas contains two sums.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.