Sukhoi State Technical University of Gomel (Gomel, Belarus):

Yu. L. Bobarikin, Cand. Eng., Associate Prof., Head of the Dept. of Metallurgy and Materials Processing Technology, e-mail: bobarikin@tut.by
Ya. I. Radkin, Senior Lecturer, Dept. of Metallurgy and Materials Processing Technology, e-mail: yradkin@gmail.com
Yu. V. Martyanov, Assistant, Dept. of Metallurgy and Materials Processing Technology, e-mail: you_rock@tut.by

Byelorussian Steel Works - Management company of the “Byelorussian Metallurgical Company” holding (Zhlobin, Belarus):
A. V. Strelchenko, Technological Engineer of the 2nd category, Laboratory of rolling production of the Research center - the Branch laboratory of technology of metallurgical and steel wire production, e-mail: stavr-sany.94@mail.ru

The problems associated with the deviation of the geometric parameters of hotdeformed seamless tubes, when they are obtained by continuous rolling on stretch reduction non-mandrel mills, are described. The study on the influence of the speed and deformation parameters of reduction on the accuracy of the obtained tube profile is carried out. The relationship between the value of the plastic tension coefficient and the stress-strain state of the tube billet during the reduction process was studied. The method of numerical simulation and practical assessment of the adequacy of the calculation was chosen as the research method. This method allows to make a deep analysis of the stressed and thermal state of the billet during processing, it also allows to determine the load parameters of tubes rolling and to visualize the results. A numerical model of the reduction process of the tube profile 93,17×12,45 mm made of steel grade TT309 is developed. As input parameters for numerical simulation, the settings of the current stretch reduction mill TPA 21/168 were taken. The range of reduction speed rates is taken in accordance with the rates used in the production of hot-deformed seamless tubes under the conditions of TPA 21/168. As a result of the study, the influence of the plastic tension coefficient on the intensity and distribution of the acting stresses in the deformation zones and in the space between stands is determined. The influence of the plastic tension coefficient on the accuracy of the obtained tube profile is determined. It is established that reduction modes with the coefficient of plastic tension in the range z = 0,55-0,65 contribute to the uniform distribution of stresses in the billet and to the increase of the accuracy of the tube profile.

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