Influence of punch face angle and reduction on flow mode in backward and combined radial backward extrusion process

Abstract

This paper is concerned with the analysis on the flow mode which determines lubrication limit such as stiction onto or sliding over punch face. The main goal of this study is to examine the influence of geometrical parameters such as punch face angle, reduction in area, and the gap height in radial direction in backward and combined radial-backward extrusion process on the flow mode and surface stresses such as sliding velocity, sliding distance and surface expansion. Annealed steel 17Cr3 was selected as a model material, a rigid-plastic material, for simulation, which was conducted using a commercially available FEA tool, Deform 2-D, programmed in a rigid plasticity theory. Change of flow mode during deformation was also investigated to find under which conditions of process parameter adopted the flow mode changes from stiction to transition or transition to sliding. In this paper, sliding velocities were quantitatively analyzed to determine the flow mode.