Stasevskyi S. Improvement of resource-saving technologies based on the development of calculations of parameters for the production of hot-rolled oil and gas pipes

Dissertation thesis in support of candidature for a technical degree in speciality 05.03.05 – Processes and machines of chipless shaping. - National Metallurgical Academy of Ukraine, Kremenchuk Mykhailo Ostrogradsky National University, Kremenchuk, 2021. The dissertation thesis is aimed at the development of metal-saving technologies for the production of hot-deformed pipes of a wide size and grade assortment at the pipe-rolling plants with pilgrim mills. In the dissertation thesis, a new solution of the scientific and technical problem has been completed, which consists in developing elements of the theory and the foundations of new metal-saving pipe production technologies, that provide a significant reduction in the technological shorts in dummy and pilger head on the pilgrim mills. The problem is solved by theoretical and experimental studies of the processes of the screw and periodic rolling, as well as radial compression of the ends of the shells on hydraulic forging presses. The practical significance of the results obtained is the creation of the new competitive technologies for the production of pipes at the pipe-rolling plants with pilgrim mills from continuous cast steel billet. New technologies have been developed for preparing the front and rear ends of the shells on the rotary piercer, planetary-type rolling machines and hydraulic forging presses, which provide a reduction in the mass of the shorts of the seed ends of the pipes by 50-75%, a decrease in the seed time to 50% and an increase in productivity of the pilgrim mill by 1.5 -3.0%. The study of the process of periodic rolling of the rear ends of the blooms on the free section of the mandrel was further developed, which made it possible to improve the technology of rolling the pilger head and reduce its mass by 40-85% depending on the D/S ratio.