Tula State University, Tula, Russia:

A. A. Pasynkov, Assistant Professor, Department of Mechanics of Plastic Forming, sulee@mail.ru
V. I. Tregubov, Professor, Department of Mechanics of Plastic Forming, tula@rambler.ru
O. I. Boriskin, Professor, Head of the Department of Instrumental and Metrological Systems, mpf-tula@rambler.ru

The article presents the results of investigations of the backward extrusion operation of pipe workpieces to produce hollow thin-walled products with a changing cross-sectional area in the longitudinal direction. The process is very complex in terms of implementation, since considering various factors, this process can be carried out either with defects in the formation of geometry of the parts, or with significant forming forces, or with critical values of stresses and deformations. Therefore, the article presents the generalized research results on the pipe workpiece extrusion from 6Al-4V non-ferrous titanium alloy. The results of the conducted studies have allowed determining the influence of geometric characteristics of a working tool, friction, degree of deformation, temperature and forming velocity on formation of the part geometry, forces and stress. A statistical study of the results obtained was performed. Secondary mathematical models that make it possible to estimate an impact of the considered parameters upon the power characteristics of operations are obtained. The forming velocity conditions, which allow to ensure minimum process forces and to provide prescribed geometric characteristics of the products given different process variables and parameters of the tool geometry, have been established by analyzing simulation results. The factors that are most affecting the folding under deforming tool are identified. The results obtained can be used as recommendations for manufacturing of cylindrical hollow products through implementation of backward extrusion.

This work was supported by grants NSh-2601.2020.8 (НШ-2601.2020.8).

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