Effect of the tool geometry on the force mode of the combined radial-direct extrusion with compression

Abstract

A possibility has been investigated to use an energy method to calculate the energy-force parameters for the cold extrusion processes involving components of complex configuration. A mathematical model has been proposed for the process of combined sequential radial-direct extrusion with compression with the presence of triangular kinematic modules. The use of the triangular kinematic modules with curvilinear and straight-line boundaries has made it possible to describe the sites of intense deformation, which correspond to the steady stage of the deformation process. It has been proposed to apply an upper estimate of the power of forces that deform a kinematic module of the triangular shape of the transition zone from the radial flow of metal to direct extrusion. This has made it possible to derive the magnitude of the reduced deformation pressure in the analytical form as a function of the geometric and technological parameters of the extrusion process. The margin of error, compared to numerical calculations without the use of the upper estimate, does not exceed 0.2‒1 %. The role of an optimization parameter belongs to aI(0,1), which is responsible for the shape of the curvilinear boundary of the inner triangular kinematic module. We have derived an analytical expression for the optimal value of the α parameter and analyzed a change in the magnitude of the reduced deformation pressure at different ratios of the process geometric parameters. It has been established that the optimal values of the angle of inclination of the forming mandrel β lie between 20° and 30° for different ratios of the deformation process. It has been justified that the use of combined sequential extrusion in the manufacture of hollow components with a flange, when compared to the application of simple deformation schemes, improves the process technological possibilities. The lack of study of the schemes of the combined radial-direct extrusion process with the compression of components of the type of sleeve, as well as the lack of recommendations for calculating the energy force parameters of the process, have been confirmed. The calculation scheme of a given process, developed on the basis of an energy method, makes it possible to predict the force mode for the steady stage under different technological parameters of the deformation process. The data acquired on the estimation of the optimal parameters for tool configuration would help devise appropriate design and technology recommendations