Основи забезпечення якості та зниження трудомісткості механічної обробки складнопрофільної формуючої оснастки для харчової промисловості
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Дата
2021
ORCID
DOI
Науковий ступінь
доктор технічних наук
Рівень дисертації
докторська дисертація
Шифр та назва спеціальності
05.02.08 – технологія машинобудування
Рада захисту
Спеціалізована вчена рада Д 64.050.12
Установа захисту
Національний технічний університет "Харківський політехнічний інститут"
Науковий керівник
Новіков Федір Васильович
Члени комітету
Пермяков Олександр Анатолійович
Пижов Іван Миколайович
Зубкова Ніна Вікторівна
Пижов Іван Миколайович
Зубкова Ніна Вікторівна
Видавець
Національний технічний університет "Харківський політехнічний інститут"
Анотація
Дисертація на здобуття наукового ступеня доктора технічних наук за спеціальністю 05.02.08 – технологія машинобудування. Національний технічний університет ''Харківський політехнічний інститут''. – Харків, 2021. Дисертацію присвячено вирішенню актуальної науково-прикладної проблеми теоретичного визначення й обґрунтування умов суттєвого підвищення якості, точності, продуктивності й зниження трудомісткості механічної обробки шляхом зниження її теплової й силової напруженостей та на цій основі розроблення ефективних технологічних процесів обробки складнопрофільної формуючої оснастки для харчової промисловості із застосуванням сучасних високообертових металорізальних верстатів із ЧПУ типу "обробний центр" та прогресивних різальних лезових твердосплавних і керамічних інструментів зі зносостійкими покриттями. Для цього в роботі розроблено спрощені математичні моделі визначення температури різання при шліфуванні та лезовій обробці. Встановлено, що знизити температуру різання
та підвищити якість і продуктивність обробки можна шляхом зниження максимальної температури різання до рівня та нижче температури плавлення оброблюваного матеріалу. Показано, що максимальна температура різання – це новий універсальний технологічний параметр механічної обробки, при
досягненні якої все тепло, що виділяється при різанні, надходить в стружку, та яка визначається відношенням енергоємності обробки до добутку питомої теплоємності й щільності оброблюваного матеріалу. Встановлено, що максимальна температура різання при точінні менше, ніж при шліфуванні та
може приймати значення, які менші температури плавлення оброблюваного матеріалу, що розширює технологічні можливості лезової обробки порівняно із шліфуванням. Розроблено уточнюючі математичні моделі визначення параметрів силової напруженості при лезовій обробці та пружних переміщень,
які виникають в технологічній системі, що дозволило обґрунтувати технологічні можливості зниження енергоємності обробки і сили різання та підвищення точності обробки. На цій основі створено методологію розроблення та впровадження ефективних технологій лезової обробки, особливо
високошвидкісного різання (точіння, розточування та фрезування). Це дозволило до 10 разів знизити трудомісткість обробки та до 200 разів розширити номенклатуру виготовлення складнопрофільної формуючої оснастки для харчової промисловості в умовах дрібносерійного та штучного виробництва із забезпеченням її високої якості та конкурентоспроможності.
The dissertation on competition of a scientific degree of the doctor of technical sciences on a specialty 05.02.08 – technology of mechanical engineering. National Technical University ''Kharkiv Polytechnic Institute''. Kharkiv, 2021. Dissertation is devoted to the solution of the actual scientific and applied problem of the theoretical definition and substantiation of the conditions for a significant increase in quality, accuracy, productivity and a decrease in the labor intensity of machining by reducing its thermal and power tensions and, on this basis, the development of effective technological processes for machining of complex molding equipment for the food industry using modern high-speed CNC metal cutting machines of the ``machining center'' type and progressive cutting blade carbide and ceramic tools with wear-resistant coatings. For this, the simplified mathematical models have been developed for determining the cutting temperature during grinding and blade processing, based on taking into account the balance of heat arising in the cutting zone and entering the facial layer of the work piece, and forming chips and coolant. The main direction of reducing the cutting temperature, improving the quality and productivity of processing has been established, which consists of reducing the maximum cutting temperature to the level and below the melting temperature of the material being processed. It is shown that the maximum cutting temperature is a new universal technological parameter of mechanical restoration/ tooling, upon reaching which all the heat generated during cutting goes to the chips, and which is determined by the ratio of the energy consumption of processing to the product of the specific heat and density of the processed material. It is shown that the difference between the calculated and experimental values of the cutting temperature during grinding does not exceed 12%, which indicates the reliability of the developed mathematical model for determining the cutting temperature. Calculations have established that in real grinding conditions, the ratio of the specified and maximum grinding temperatures can vary only within 0 ... 0.4 in connection with the excess of the maximum cutting temperature and the melting temperature of the processed material due to a significant increase of conventional cutting stress. This expands the technological opportunities of turning in comparison with grinding. Calculations have established that the most significant reduction in the cutting temperature during grinding can be achieved with intermittent grinding under conditions of equality of the lengths of the working protrusion and the cutout of the intermittent wheel, and under increase in the number of working protrusions of the wheel. In this case, the cutting temperature can be reduced by more than 2 times compared to the cutting temperature when grinding with a continuous wheel. However, the maximum cutting temperature in this case takes on values that are significantly higher than the melting temperature of the material being processed. This limits the technological possibilities of interrupted grinding in comparison with edge cutting machining. A refined mathematical model for determining the cutting temperature during blade processing has been developed, which is based on the number of shearing elementary volumes of the processed material arising in the cutting zone. It was found that with their increase, the cutting temperature can increase up to 10 times. This is possible when grinding in conditions of continuous contact of the bond of the grinding wheel with the processed material. During blade processing, the amount of shearing elementary volumes of the processed material arising in the cutting zone is insignificant, which makes it possible to reduce the cutting temperature and increase the quality and productivity of processing. It has been established that in the conditions of finishing blade processing, especially in high-speed cutting operations (turning, boring and milling with modern cutting carbide and ceramic tools with wear-resistant coatings), it is possible to achieve a much higher processing performance at a given cutting temperature than when grinding. This is due to a significant decrease of the maximum cutting temperature. A mathematical model was developed for determining the parameters of power tension during blade processing, taking into account the updated values of the conditional shear angle of the processed material. It is shown that the radial component of the cutting force prevails in the formation of the conditional shear angle of the machined material, which leads to its significant decrease (by 1.5 times) in comparison with the calculated values obtained on the basis of known dependencies. This made it possible to substantiate the conditions for reducing the energy consumption of processing and cutting force. A mathematical model has been developed for determining the elastic displacements arising in the technological system, and it has been established that they depend, first of all, on the method of mechanical treatment and its energy intensity. Therefore, the main way to increase the accuracy and productivity of processing is the use the modern technologies of high-speed blade processing in finishing operations instead of traditional technologies of grinding and blade processing. On this basis, a methodology was created for the development and implementation of effective technologies for blade processing using modern highspeed metal-cutting machines with CNC of ''machining center'' type, and cutting blade carbide and ceramic tools with wear-resistant coatings of foreign production. It is shown that they allow to reduce energy consumption up to 10 times or more and to increase processing productivity while ensuring high quality and accuracy of the processed surfaces in comparison with grinding. This made it possible to reduce the labor intensity of processing up to 10 times and to expand the range of production of molding tooling for the food industry up to 200 times in the conditions of small batch and unit production, ensuring its high quality and competitiveness.
The dissertation on competition of a scientific degree of the doctor of technical sciences on a specialty 05.02.08 – technology of mechanical engineering. National Technical University ''Kharkiv Polytechnic Institute''. Kharkiv, 2021. Dissertation is devoted to the solution of the actual scientific and applied problem of the theoretical definition and substantiation of the conditions for a significant increase in quality, accuracy, productivity and a decrease in the labor intensity of machining by reducing its thermal and power tensions and, on this basis, the development of effective technological processes for machining of complex molding equipment for the food industry using modern high-speed CNC metal cutting machines of the ``machining center'' type and progressive cutting blade carbide and ceramic tools with wear-resistant coatings. For this, the simplified mathematical models have been developed for determining the cutting temperature during grinding and blade processing, based on taking into account the balance of heat arising in the cutting zone and entering the facial layer of the work piece, and forming chips and coolant. The main direction of reducing the cutting temperature, improving the quality and productivity of processing has been established, which consists of reducing the maximum cutting temperature to the level and below the melting temperature of the material being processed. It is shown that the maximum cutting temperature is a new universal technological parameter of mechanical restoration/ tooling, upon reaching which all the heat generated during cutting goes to the chips, and which is determined by the ratio of the energy consumption of processing to the product of the specific heat and density of the processed material. It is shown that the difference between the calculated and experimental values of the cutting temperature during grinding does not exceed 12%, which indicates the reliability of the developed mathematical model for determining the cutting temperature. Calculations have established that in real grinding conditions, the ratio of the specified and maximum grinding temperatures can vary only within 0 ... 0.4 in connection with the excess of the maximum cutting temperature and the melting temperature of the processed material due to a significant increase of conventional cutting stress. This expands the technological opportunities of turning in comparison with grinding. Calculations have established that the most significant reduction in the cutting temperature during grinding can be achieved with intermittent grinding under conditions of equality of the lengths of the working protrusion and the cutout of the intermittent wheel, and under increase in the number of working protrusions of the wheel. In this case, the cutting temperature can be reduced by more than 2 times compared to the cutting temperature when grinding with a continuous wheel. However, the maximum cutting temperature in this case takes on values that are significantly higher than the melting temperature of the material being processed. This limits the technological possibilities of interrupted grinding in comparison with edge cutting machining. A refined mathematical model for determining the cutting temperature during blade processing has been developed, which is based on the number of shearing elementary volumes of the processed material arising in the cutting zone. It was found that with their increase, the cutting temperature can increase up to 10 times. This is possible when grinding in conditions of continuous contact of the bond of the grinding wheel with the processed material. During blade processing, the amount of shearing elementary volumes of the processed material arising in the cutting zone is insignificant, which makes it possible to reduce the cutting temperature and increase the quality and productivity of processing. It has been established that in the conditions of finishing blade processing, especially in high-speed cutting operations (turning, boring and milling with modern cutting carbide and ceramic tools with wear-resistant coatings), it is possible to achieve a much higher processing performance at a given cutting temperature than when grinding. This is due to a significant decrease of the maximum cutting temperature. A mathematical model was developed for determining the parameters of power tension during blade processing, taking into account the updated values of the conditional shear angle of the processed material. It is shown that the radial component of the cutting force prevails in the formation of the conditional shear angle of the machined material, which leads to its significant decrease (by 1.5 times) in comparison with the calculated values obtained on the basis of known dependencies. This made it possible to substantiate the conditions for reducing the energy consumption of processing and cutting force. A mathematical model has been developed for determining the elastic displacements arising in the technological system, and it has been established that they depend, first of all, on the method of mechanical treatment and its energy intensity. Therefore, the main way to increase the accuracy and productivity of processing is the use the modern technologies of high-speed blade processing in finishing operations instead of traditional technologies of grinding and blade processing. On this basis, a methodology was created for the development and implementation of effective technologies for blade processing using modern highspeed metal-cutting machines with CNC of ''machining center'' type, and cutting blade carbide and ceramic tools with wear-resistant coatings of foreign production. It is shown that they allow to reduce energy consumption up to 10 times or more and to increase processing productivity while ensuring high quality and accuracy of the processed surfaces in comparison with grinding. This made it possible to reduce the labor intensity of processing up to 10 times and to expand the range of production of molding tooling for the food industry up to 200 times in the conditions of small batch and unit production, ensuring its high quality and competitiveness.
Опис
Ключові слова
автореферат дисертації, технологічний процес, дрібносерійне виробництво, штучне виробництво, оброблювальний центр, фінішні операції, математична модель, температура різання, точність обробки, продуктивність обробки, енергоємність обробки, пружне переміщення, technological process, small batch production, unit production, machining center, finishing operations, mathematical model, cutting temperature, processing accuracy, process efficiency, process energy capacity, elastic displacement
Бібліографічний опис
Полянський В. І. Основи забезпечення якості та зниження трудомісткості механічної обробки складнопрофільної формуючої оснастки для харчової промисловості [Електронний ресурс] : автореф. дис. ... д-ра техн. наук : спец. 05.02.08 / Володимир Іванович Полянський ; [наук. консультант Новіков Ф. В.] ; Нац. техн. ун-т "Харків. політехн. ін-т". – Харків, 2021. – 40 с. – Бібліогр.: с. 29-36. – укр.