КОНСТРУКТИВНІ АСПЕКТИ ПРОЕКТУВАННЯ ТА ЕКСПЛУАТАЦІЇ ОСНАЩЕННЯ ДЛЯ ГВИНТОВОЇ ЕКСТРУЗІЇ

Abstract

The present paper introduces a twist extrusion (TE) process and special equipment capable of processing of round and prismatic bars with uniform deformation and reports analytical, and numerical modeling of the process. It is shown that the ability to treat round bars can be achieved by design of special off-axis TE dies in which the axis of the twist surface is displaced from the central axis of the bar being processed. Analytical model developed in the present study explains why using off-axis TE dies leads to uniform deformation and how this deformation uniformity depends on the die geometry. The main conclusions made upon analytical modeling are confirmed with complement finite element simulations. The simulations also show that the main deformation mode in off-axis TE is simple shear at the intersection planes between the twist and the straight channels of the die. Features of design and operation of dies for metal working with pressure from the point of view of design features and working conditions of equipment for severe plastic deformation of blanks by TE are considered. Based on the analysis of required modes of deformation of titanium and iron-nickel alloys, the require-ments for the construction of matrices, materials for their manufacture, lubricating-technological environments, as well as the working conditions of the twist matrices. Recommendations are proposed for the development of a rational design of technological equipment for deformation of blanks by twist extrusion in a batch production. On their basis, technical solutions and constructive measures to improve the design of the tooling for the process of twist extrusion of high-strength alloys for aircraft engineering are proposed. Examples of developed various structural schemes for the implementation of twist matrices are shown. It is shown that a matrix with grooves in a screw channel evolves into a promising construction of the matrix for the realization of screw extrusion of blanks of different sections. This allows to reduce friction between the blank, the counter-blanks and the matrix. The developed equipment for severe plastic deformation by TE can be used for technological processes of processing different aviation alloys and technological process of high-effectiveness titanium materials producing from powders.